ModernGL¶

ModernGL is a high performance rendering module for Python.

Installation¶

Install ModernGL with pip:

$ pip install ModernGL

Version check:

$ python -m moderngl --version  # 5.0.0 and above
$ python -m ModernGL --version  # before 5.0.0

Note

The package name is “ModernGL” for ModernGL<5.0.0
The package name is “moderngl” for ModernGL>=5.0.0

Reference¶

Context¶

class moderngl.Context¶: Class exposing OpenGL features. ModernGL objects can be created from this class.

Create¶

moderngl.create_context(require=None) → Context¶

Create a ModernGL context by loading OpenGL functions from an existing OpenGL context. An OpenGL context must exists. If rendering is done without a window please use the create_standalone_context() instead.

Example:

# Accept the current context version
ctx = moderngl.create_context()

# Require at least OpenGL 4.3
ctx = moderngl.create_context(require=430)

Keyword Arguments:
	require (int) – OpenGL version code.
Returns:	`Context` object

moderngl.create_standalone_context(require=None) → Context¶

Create a standalone ModernGL context.

Example:

# Create a context with highest possible supported version
ctx = moderngl.create_context()

# Require at least OpenGL 4.3
ctx = moderngl.create_context(require=430)

Keyword Arguments:
	require (int) – OpenGL version code.
Returns:	`Context` object

ModernGL Objects¶

Context.program(vertex_shader, fragment_shader=None, geometry_shader=None, tess_control_shader=None, tess_evaluation_shader=None, varyings=()) → Program¶

Create a Program object.

Only linked programs will be returned.

A single shader in the shaders parameter is also accepted. The varyings are only used when a transform program is created.

Parameters:	shaders (list) – A list of `Shader` objects. varyings (list) – A list of varying names.
Returns:	`Program` object

Context.simple_vertex_array(program, buffer, *attributes, index_buffer=None, index_element_size=4) → VertexArray¶

Create a VertexArray object.

Keyword Arguments:
Parameters:	program (Program) – The program used when rendering. buffer (Buffer) – The buffer. attributes (list) – A list of attribute names.
	index_element_size (int) – byte size of each index element, 1, 2 or 4. index_buffer (Buffer) – An index buffer.
Returns:	`VertexArray` object

Context.vertex_array(program, content, index_buffer=None, index_element_size=4, skip_errors=False) → VertexArray¶

Create a VertexArray object.

Keyword Arguments:
Parameters:	program (Program) – The program used when rendering. content (list) – A list of (buffer, format, attributes). index_buffer (Buffer) – An index buffer.
	index_element_size (int) – byte size of each index element, 1, 2 or 4. skip_errors (bool) – Ignore skip_errors varyings.
Returns:	`VertexArray` object

Context.buffer(data=None, reserve=0, dynamic=False) → Buffer¶

Create a Buffer object.

Keyword Arguments:
Parameters:	data (bytes) – Content of the new buffer.
	reserve (int) – The number of bytes to reserve. dynamic (bool) – Treat buffer as dynamic.
Returns:	`Buffer` object

Context.texture(size, components, data=None, samples=0, alignment=1, dtype='f1') → Texture¶

Create a Texture object.

Keyword Arguments:
Parameters:	size (tuple) – The width and height of the texture. components (int) – The number of components 1, 2, 3 or 4. data (bytes) – Content of the texture.
	samples (int) – The number of samples. Value 0 means no multisample format. alignment (int) – The byte alignment 1, 2, 4 or 8. dtype (str) – Data type.
Returns:	`Texture` object

Context.depth_texture(size, data=None, samples=0, alignment=4) → Texture¶

Create a Texture object.

Keyword Arguments:
Parameters:	size (tuple) – The width and height of the texture. data (bytes) – Content of the texture.
	samples (int) – The number of samples. Value 0 means no multisample format. alignment (int) – The byte alignment 1, 2, 4 or 8.
Returns:	`Texture` object

Context.texture3d(size, components, data=None, alignment=1, dtype='f1') → Texture3D¶

Create a Texture3D object.

Keyword Arguments:
Parameters:	size (tuple) – The width, height and depth of the texture. components (int) – The number of components 1, 2, 3 or 4. data (bytes) – Content of the texture.
	alignment (int) – The byte alignment 1, 2, 4 or 8. dtype (str) – Data type.
Returns:	`Texture3D` object

Context.texture_array(size, components, data=None, alignment=1, dtype='f1') → TextureArray¶

Create a TextureArray object.

Keyword Arguments:
Parameters:	size (tuple) – The `(width, height, layers)` of the texture. components (int) – The number of components 1, 2, 3 or 4. data (bytes) – Content of the texture. The size must be `(width, height * layers)` so each layer is stacked vertically.
	alignment (int) – The byte alignment 1, 2, 4 or 8. dtype (str) – Data type.
Returns:	`Texture3D` object

Context.texture_cube(size, components, data=None, alignment=1, dtype='f1') → TextureCube¶

Create a TextureCube object.

Keyword Arguments:
Parameters:	size (tuple) – The width, height of the texture. Each side of the cube will have this size. components (int) – The number of components 1, 2, 3 or 4. data (bytes) – Content of the texture.
	alignment (int) – The byte alignment 1, 2, 4 or 8. dtype (str) – Data type.
Returns:	`TextureCube` object

Context.simple_framebuffer(size, components=4, samples=0, dtype='f1') → Framebuffer¶

A Framebuffer is a collection of buffers that can be used as the destination for rendering. The buffers for Framebuffer objects reference images from either Textures or Renderbuffers.

Keyword Arguments:
Parameters:	size (tuple) – The width and height of the renderbuffer. components (int) – The number of components 1, 2, 3 or 4.
	samples (int) – The number of samples. Value 0 means no multisample format. dtype (str) – Data type.
Returns:	`Framebuffer` object

Context.framebuffer(color_attachments=(), depth_attachment=None) → Framebuffer¶

A Framebuffer is a collection of buffers that can be used as the destination for rendering. The buffers for Framebuffer objects reference images from either Textures or Renderbuffers.

Parameters:	color_attachments (list) – A list of `Texture` or `Renderbuffer` objects. depth_attachment (Renderbuffer or Texture) – The depth attachment.
Returns:	`Framebuffer` object

Context.renderbuffer(size, components=4, samples=0, dtype='f1') → Renderbuffer¶

Renderbuffer objects are OpenGL objects that contain images. They are created and used specifically with Framebuffer objects.

Keyword Arguments:
Parameters:	size (tuple) – The width and height of the renderbuffer. components (int) – The number of components 1, 2, 3 or 4.
	samples (int) – The number of samples. Value 0 means no multisample format. dtype (str) – Data type.
Returns:	`Renderbuffer` object

Context.depth_renderbuffer(size, samples=0) → Renderbuffer¶

Renderbuffer objects are OpenGL objects that contain images. They are created and used specifically with Framebuffer objects.

Keyword Arguments:
Parameters:	size (tuple) – The width and height of the renderbuffer.
	samples (int) – The number of samples. Value 0 means no multisample format.
Returns:	`Renderbuffer` object

Context.scope(framebuffer, enable_only=None, textures=(), uniform_buffers=(), storage_buffers=()) → Scope¶

Create a Scope object.

Keyword Arguments:
Parameters:	framebuffer (Framebuffer) – The framebuffer to use when entering. enable_only (int) – The enable_only flags to set when entering.
	textures (list) – List of (texture, binding) tuples. uniform_buffers (list) – List of (buffer, binding) tuples. storage_buffers (list) – List of (buffer, binding) tuples.

Context.query(samples=False, any_samples=False, time=False, primitives=False) → Query¶

Create a Query object.

Keyword Arguments:
	samples (bool) – Query `GL_SAMPLES_PASSED` or not. any_samples (bool) – Query `GL_ANY_SAMPLES_PASSED` or not. time (bool) – Query `GL_TIME_ELAPSED` or not. primitives (bool) – Query `GL_PRIMITIVES_GENERATED` or not.

Context.compute_shader(source) → ComputeShader¶

A ComputeShader is a Shader Stage that is used entirely for computing arbitrary information. While it can do rendering, it is generally used for tasks not directly related to drawing.

Parameters:	source (str) – The source of the compute shader.
Returns:	`ComputeShader` object

Context.sampler(repeat_x=True, repeat_y=True, repeat_z=True, filter=None, anisotropy=1.0, compare_func='?', border_color=None, min_lod=-1000.0, max_lod=1000.0) → Sampler¶

Create a Sampler object.

Keyword Arguments:

repeat_x (bool) – Repeat texture on x
repeat_y (bool) – Repeat texture on y
repeat_z (bool) – Repeat texture on z
filter (tuple) – The min and max filter
anisotropy (float) – Number of samples for anisotropic filtering. Any value greater than 1.0 counts as a use of anisotropic filtering
compare_func – Compare function for depth textures
border_color (tuple) – The (r, g, b, a) color for the texture border. When this value is set the repeat_ values are overriden setting the texture wrap to return the border color when outside [0, 1] range.
min_lod (float) – Minimum level-of-detail parameter (Default -1000.0). This floating-point value limits the selection of highest resolution mipmap (lowest mipmap level)
max_lod (float) – Minimum level-of-detail parameter (Default 1000.0). This floating-point value limits the selection of the lowest resolution mipmap (highest mipmap level)

Context.clear_samplers(start=0, end=-1)¶

Unbinds samplers from texture units. Sampler bindings do clear automatically between every frame, but lingering samplers can still be a source of weird bugs during the frame rendering. This methods provides a fairly brute force and efficient way to ensure texture units are clear.

Keyword Arguments:
	start (int) – The texture unit index to start the clearing samplers stop (int) – The texture unit index to stop clearing samplers

Example:

# Clear texture unit 0, 1, 2, 3, 4
ctx.clear_samplers(start=0, end=5)

# Clear texture unit 4, 5, 6, 7
ctx.clear_samplers(start=4, end=8)

Methods¶

Context.clear(red=0.0, green=0.0, blue=0.0, alpha=0.0, depth=1.0, viewport=None)¶

Clear the bound framebuffer. By default clears the screen.

If the viewport is not None then scrissor test will be used to clear the given viewport.

If the viewport is a 2-tuple it will clear the (0, 0, width, height) where (width, height) is the 2-tuple.

If the viewport is a 4-tuple it will clear the given viewport.

Keyword Arguments:
Parameters:	red (float) – color component. green (float) – color component. blue (float) – color component. alpha (float) – alpha component. depth (float) – depth value.
	viewport (tuple) – The viewport.

Context.enable_only(flags)¶

Clears all existing flags applying new ones

Available flags:

moderngl.NOTHING
moderngl.BLEND
moderngl.DEPTH_TEST
moderngl.CULL_FACE
moderngl.RASTERIZER_DISCARD

Examples:

# Disable all flags
ctx.enable_only(moderngl.NOTHING)

# Ensure only depth testing and face culling is enabled
ctx.enable_only(moderngl.DEPTH_TEST | moderngl.CULL_FACE)

Parameters:	flags (EnableFlag) – The flags to enable

Context.enable(flags)¶

Enable flags.

For valid flags, please see enable_only().

Examples:

# Enable a single flag
ctx.enable(moderngl.DEPTH_TEST)

# Enable multiple flags
ctx.enable(moderngl.DEPTH_TEST | moderngl.CULL_FACE | moderngl.BLEND)

Parameters:	flag (int) – The flags to enable.

Context.disable(flags)¶

Disable flags.

For valid flags, please see enable_only().

Examples:

# Only disable depth testing
ctx.disable(moderngl.DEPTH_TEST)

# Disable depth testing and face culling
ctx.disable(moderngl.DEPTH_TEST | moderngl.CULL_FACE)

Parameters:	flag (int) – The flags to disable.

Context.finish()¶: Wait for all drawing commands to finish.

Context.copy_buffer(dst, src, size=-1, read_offset=0, write_offset=0)¶

Copy buffer content.

Keyword Arguments:
Parameters:	dst (Buffer) – The destination buffer. src (Buffer) – The source buffer. size (int) – The number of bytes to copy.
	read_offset (int) – The read offset. write_offset (int) – The write offset.

Context.copy_framebuffer(dst, src)¶

Copy framebuffer content.

Use this method to:

blit framebuffers.

copy framebuffer content into a texture.

downsample framebuffers. (it will allow to read the framebuffer’s content)

downsample a framebuffer directly to a texture.

Parameters:	dst (Framebuffer or Texture) – Destination framebuffer or texture. src (Framebuffer) – Source framebuffer.

Context.detect_framebuffer(glo=None) → Framebuffer¶

Detect framebuffer.

Parameters:	glo (int) – Framebuffer object.
Returns:	`Framebuffer` object

Attributes¶

Context.line_width¶

Set the default line width.

Type:	float

Context.point_size¶

Set/get the default point size.

Type:	float

Context.depth_func¶

Set the default depth func. The depth function is set using a string.

Example:

ctx.depth_func = '<='  # GL_LEQUAL
ctx.depth_func = '<'   # GL_LESS
ctx.depth_func = '>='  # GL_GEQUAL
ctx.depth_func = '>'   # GL_GREATER
ctx.depth_func = '=='  # GL_EQUAL
ctx.depth_func = '!='  # GL_NOTEQUAL
ctx.depth_func = '0'   # GL_NEVER
ctx.depth_func = '1'   # GL_ALWAYS

Type:	int

Context.blend_func¶

Set the blend depth func.

Example:

ctx.enable(moderngl.BLEND)
ctx.blend_func = moderngl.SRC_ALPHA, moderngl.ONE_MINUS_SRC_ALPHA

Type:	tuple

Context.viewport¶

The viewport of the active framebuffer. Modifies or gets the viewport.

Example:

>>> ctx.viewport
(0, 0, 1280, 720)
>>> ctx.viewport = (0, 0, 640, 360)
>>> ctx.viewport
(0, 0, 640, 360)

If no framebuffer is bound (0, 0, 0, 0) will be returned.

Type:	tuple

Context.version_code¶

The OpenGL version code. Reports 410 for OpenGL 4.1

Type:	int

Context.screen¶

A Framebuffer instance representing the screen usually set when creating a context with create_context() attaching to an existing context. This is the special system framebuffer represented by framebuffer id=0.

When creating a standalone context this property is not set.

Type:	Framebuffer

Context.fbo¶

The active framebuffer. Set every time Framebuffer.use() is called.

Type:	Framebuffer

Context.front_face¶

The front_face. Acceptable values are 'ccw' (default) or 'cw'.

Face culling must be enabled for this to have any effect: ctx.enable(moderngl.CULL_FACE).

Example:

# Triangles winded counter-clockwise considered front facing
ctx.front_face = 'ccw'
# Triangles winded clockwise considered front facing
ctx.front_face = 'cw'

Type:	str

Context.wireframe¶

Wireframe settings for debugging.

Type:	bool

Context.max_samples¶

The maximum supported number of samples for multisampling

Type:	int

Context.max_integer_samples¶

The max integer samples.

Type:	int

Context.max_texture_units¶

The max texture units.

Type:	int

Context.default_texture_unit¶

The default texture unit.

Type:	int

Context.max_anisotropy¶

The maximum value supported for anisotropic filtering.

Type:	float

Context.multisample¶

Enable/disable multisample mode (GL_MULTISAMPLE). This property is write only.

Example:

# Enable
ctx.multisample = True
# Disable
ctx.multisample = False

Type:	bool

Context.patch_vertices¶

The number of vertices that will be used to make up a single patch primitive.

Type:	int

Context.error¶

The result of glGetError() but human readable. This values is provided for debug purposes only and is likely to reduce performace when used in a draw loop.

Type:	str

Context.info¶

Information about the context

Example:

{
    'GL_VENDOR': 'NVIDIA Corporation',
    'GL_RENDERER': 'NVIDIA GeForce GT 650M OpenGL Engine',
    'GL_VERSION': '4.1 NVIDIA-10.32.0 355.11.10.10.40.102',
    'GL_POINT_SIZE_RANGE': (1.0, 2047.0),
    'GL_SMOOTH_LINE_WIDTH_RANGE': (0.5, 1.0),
    'GL_ALIASED_LINE_WIDTH_RANGE': (1.0, 1.0),
    'GL_POINT_FADE_THRESHOLD_SIZE': 1.0,
    'GL_POINT_SIZE_GRANULARITY': 0.125,
    'GL_SMOOTH_LINE_WIDTH_GRANULARITY': 0.125,
    'GL_MIN_PROGRAM_TEXEL_OFFSET': -8.0,
    'GL_MAX_PROGRAM_TEXEL_OFFSET': 7.0,
    'GL_MINOR_VERSION': 1,
    'GL_MAJOR_VERSION': 4,
    'GL_SAMPLE_BUFFERS': 0,
    'GL_SUBPIXEL_BITS': 8,
    'GL_CONTEXT_PROFILE_MASK': 1,
    'GL_UNIFORM_BUFFER_OFFSET_ALIGNMENT': 256,
    'GL_DOUBLEBUFFER': False,
    'GL_STEREO': False,
    'GL_MAX_VIEWPORT_DIMS': (16384, 16384),
    'GL_MAX_3D_TEXTURE_SIZE': 2048,
    'GL_MAX_ARRAY_TEXTURE_LAYERS': 2048,
    'GL_MAX_CLIP_DISTANCES': 8,
    'GL_MAX_COLOR_ATTACHMENTS': 8,
    'GL_MAX_COLOR_TEXTURE_SAMPLES': 8,
    'GL_MAX_COMBINED_FRAGMENT_UNIFORM_COMPONENTS': 233472,
    'GL_MAX_COMBINED_GEOMETRY_UNIFORM_COMPONENTS': 231424,
    'GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS': 80,
    'GL_MAX_COMBINED_UNIFORM_BLOCKS': 70,
    'GL_MAX_COMBINED_VERTEX_UNIFORM_COMPONENTS': 233472,
    'GL_MAX_CUBE_MAP_TEXTURE_SIZE': 16384,
    'GL_MAX_DEPTH_TEXTURE_SAMPLES': 8,
    'GL_MAX_DRAW_BUFFERS': 8,
    'GL_MAX_DUAL_SOURCE_DRAW_BUFFERS': 1,
    'GL_MAX_ELEMENTS_INDICES': 150000,
    'GL_MAX_ELEMENTS_VERTICES': 1048575,
    'GL_MAX_FRAGMENT_INPUT_COMPONENTS': 128,
    'GL_MAX_FRAGMENT_UNIFORM_COMPONENTS': 4096,
    'GL_MAX_FRAGMENT_UNIFORM_VECTORS': 1024,
    'GL_MAX_FRAGMENT_UNIFORM_BLOCKS': 14,
    'GL_MAX_GEOMETRY_INPUT_COMPONENTS': 128,
    'GL_MAX_GEOMETRY_OUTPUT_COMPONENTS': 128,
    'GL_MAX_GEOMETRY_TEXTURE_IMAGE_UNITS': 16,
    'GL_MAX_GEOMETRY_UNIFORM_BLOCKS': 14,
    'GL_MAX_GEOMETRY_UNIFORM_COMPONENTS': 2048,
    'GL_MAX_INTEGER_SAMPLES': 1,
    'GL_MAX_SAMPLES': 8,
    'GL_MAX_RECTANGLE_TEXTURE_SIZE': 16384,
    'GL_MAX_RENDERBUFFER_SIZE': 16384,
    'GL_MAX_SAMPLE_MASK_WORDS': 1,
    'GL_MAX_SERVER_WAIT_TIMEOUT': -1,
    'GL_MAX_TEXTURE_BUFFER_SIZE': 134217728,
    'GL_MAX_TEXTURE_IMAGE_UNITS': 16,
    'GL_MAX_TEXTURE_LOD_BIAS': 15,
    'GL_MAX_TEXTURE_SIZE': 16384,
    'GL_MAX_UNIFORM_BUFFER_BINDINGS': 70,
    'GL_MAX_UNIFORM_BLOCK_SIZE': 65536,
    'GL_MAX_VARYING_COMPONENTS': 0,
    'GL_MAX_VARYING_VECTORS': 31,
    'GL_MAX_VARYING_FLOATS': 0,
    'GL_MAX_VERTEX_ATTRIBS': 16,
    'GL_MAX_VERTEX_TEXTURE_IMAGE_UNITS': 16,
    'GL_MAX_VERTEX_UNIFORM_COMPONENTS': 4096,
    'GL_MAX_VERTEX_UNIFORM_VECTORS': 1024,
    'GL_MAX_VERTEX_OUTPUT_COMPONENTS': 128,
    'GL_MAX_VERTEX_UNIFORM_BLOCKS': 14,
    'GL_MAX_VERTEX_ATTRIB_RELATIVE_OFFSET': 0,
    'GL_MAX_VERTEX_ATTRIB_BINDINGS': 0,
    'GL_VIEWPORT_BOUNDS_RANGE': (-32768, 32768),
    'GL_VIEWPORT_SUBPIXEL_BITS': 0,
    'GL_MAX_VIEWPORTS': 16
}

Type:	dict

Context.extra¶: Any - Attribute for storing user defined objects

Examples¶

ModernGL Context¶

import moderngl
# create a window
ctx = moderngl.create_context()
print(ctx.version_code)

Standalone ModernGL Context¶

import moderngl
ctx = moderngl.create_standalone_context()
print(ctx.version_code)

ContextManager¶

context_manager.py

import moderngl


class ContextManager:
    ctx = None

    @staticmethod
    def get_default_context(allow_fallback_standalone_context=True) -> moderngl.Context:
        '''
            Default context
        '''

        if ContextManager.ctx is None:
            try:
                ContextManager.ctx = moderngl.create_context()
            except moderngl.Error:
                if allow_fallback_standalone_context:
                    ContextManager.ctx = moderngl.create_standalone_context()
                else:
                    raise

        return ContextManager.ctx

example.py

from context_manager import ContextManager

ctx = ContextManager.get_default_context()
print(ctx.version_code)

Buffer¶

class moderngl.Buffer¶

Buffer objects are OpenGL objects that store an array of unformatted memory allocated by the OpenGL context, (data allocated on the GPU). These can be used to store vertex data, pixel data retrieved from images or the framebuffer, and a variety of other things.

A Buffer object cannot be instantiated directly, it requires a context. Use Context.buffer() to create one.

Copy buffer content using Context.copy_buffer().

Create¶

Context.buffer(data=None, reserve=0, dynamic=False) → Buffer

Create a Buffer object.

Keyword Arguments:
Parameters:	data (bytes) – Content of the new buffer.
	reserve (int) – The number of bytes to reserve. dynamic (bool) – Treat buffer as dynamic.
Returns:	`Buffer` object

Methods¶

Buffer.write(data, offset=0)¶

Write the content.

Keyword Arguments:
Parameters:	data (bytes) – The data.
	offset (int) – The offset.

Buffer.write_chunks(data, start, step, count)¶

Split data to count equal parts.

Write the chunks using offsets calculated from start, step and stop.

Parameters:	data (bytes) – The data. start (int) – First offset. step (int) – Offset increment. count (int) – The number of offsets.

Buffer.read(size=-1, offset=0) → bytes¶

Read the content.

Keyword Arguments:
Parameters:	size (int) – The size. Value `-1` means all.
	offset (int) – The offset.
Returns:	bytes

Buffer.read_into(buffer, size=-1, offset=0, write_offset=0)¶

Read the content into a buffer.

Keyword Arguments:
Parameters:	buffer (bytarray) – The buffer that will receive the content. size (int) – The size. Value `-1` means all.
	offset (int) – The read offset. write_offset (int) – The write offset.

Buffer.read_chunks(chunk_size, start, step, count) → bytes¶

Read the content.

Read and concatenate the chunks of size chunk_size using offsets calculated from start, step and stop.

Parameters:	chunk_size (int) – The chunk size. start (int) – First offset. step (int) – Offset increment. count (int) – The number of offsets.
Returns:	bytes

Buffer.read_chunks_into(buffer, chunk_size, start, step, count, write_offset=0)¶

Read the content.

Read and concatenate the chunks of size chunk_size using offsets calculated from start, step and stop.

Keyword Arguments:
Parameters:	buffer (bytarray) – The buffer that will receive the content. chunk_size (int) – The chunk size. start (int) – First offset. step (int) – Offset increment. count (int) – The number of offsets.
	write_offset (int) – The write offset.

Buffer.clear(size=-1, offset=0, chunk=None)¶

Clear the content.

Keyword Arguments:
Parameters:	size (int) – The size. Value `-1` means all.
	offset (int) – The offset. chunk (bytes) – The chunk to use repeatedly.

Buffer.bind_to_uniform_block(binding=0, offset=0, size=-1)¶

Bind the buffer to a uniform block.

Keyword Arguments:
Parameters:	binding (int) – The uniform block binding.
	offset (int) – The offset. size (int) – The size. Value `-1` means all.

Buffer.bind_to_storage_buffer(binding=0, offset=0, size=-1)¶

Bind the buffer to a shader storage buffer.

Keyword Arguments:
Parameters:	binding (int) – The shader storage binding.
	offset (int) – The offset. size (int) – The size. Value `-1` means all.

Buffer.orphan()¶

Orphan the buffer.

It is also called buffer re-specification.

Reallocate the buffer object before you start modifying it.

Since allocating storage is likely faster than the implicit synchronization, you gain significant performance advantages over synchronization.

The old storage will still be used by the OpenGL commands that have been sent previously. It is likely that the GL driver will not be doing any allocation at all, but will just be pulling an old free block off the unused buffer queue and use it, so it is likely to be very efficient.

Example

# For simplicity the VertexArray creation is omitted

>>> vbo = ctx.buffer(reserve=1024)

# Fill the buffer

>>> vbo.write(some_temorary_data)

# Issue a render call that uses the vbo

>>> vao.render(...)

# Orphan the buffer

>>> vbo.orphan()

# Issue another render call without waiting for the previous one

>>> vbo.write(some_temorary_data)
>>> vao.render(...)

Attributes¶

Buffer.size¶

The size of the buffer.

Type:	int

Buffer.dynamic¶

Is the buffer created with the dynamic flag?

Type:	bool

Buffer.glo¶

The internal OpenGL object. This values is provided for debug purposes only.

Type:	int

Buffer.extra¶: Any - Attribute for storing user defined objects

VertexArray¶

class moderngl.VertexArray¶

A VertexArray object is an OpenGL object that stores all of the state needed to supply vertex data. It stores the format of the vertex data as well as the Buffer objects providing the vertex data arrays.

In ModernGL, the VertexArray object also stores a reference for a Program object, and some Subroutine information.

A VertexArray object cannot be instantiated directly, it requires a context. Use Context.vertex_array() or Context.simple_vertex_array() to create one.

Note

Compared to OpenGL, VertexArray objects have some additional responsibilities:

Binding a Program when VertexArray.render() or VertexArray.transform() is called.
Subroutines can be assigned. Please see the example below.

Create¶

Context.simple_vertex_array(program, buffer, *attributes, index_buffer=None, index_element_size=4) → VertexArray

Create a VertexArray object.

Keyword Arguments:
Parameters:	program (Program) – The program used when rendering. buffer (Buffer) – The buffer. attributes (list) – A list of attribute names.
	index_element_size (int) – byte size of each index element, 1, 2 or 4. index_buffer (Buffer) – An index buffer.
Returns:	`VertexArray` object

Context.vertex_array(program, content, index_buffer=None, index_element_size=4, skip_errors=False) → VertexArray

Create a VertexArray object.

Keyword Arguments:
Parameters:	program (Program) – The program used when rendering. content (list) – A list of (buffer, format, attributes). index_buffer (Buffer) – An index buffer.
	index_element_size (int) – byte size of each index element, 1, 2 or 4. skip_errors (bool) – Ignore skip_errors varyings.
Returns:	`VertexArray` object

Methods¶

VertexArray.render(mode=None, vertices=-1, first=0, instances=1)¶

The render primitive (mode) must be the same as the input primitive of the GeometryShader.

Keyword Arguments:
Parameters:	mode (int) – By default `TRIANGLES` will be used. vertices (int) – The number of vertices to transform.
	first (int) – The index of the first vertex to start with. instances (int) – The number of instances.

VertexArray.render_indirect(buffer, mode=None, count=-1, first=0)¶

The render primitive (mode) must be the same as the input primitive of the GeometryShader.

The draw commands are 5 integers: (count, instanceCount, firstIndex, baseVertex, baseInstance).

Keyword Arguments:
Parameters:	buffer (Buffer) – Indirect drawing commands. mode (int) – By default `TRIANGLES` will be used. count (int) – The number of draws.
	first (int) – The index of the first indirect draw command.

VertexArray.transform(buffer, mode=None, vertices=-1, first=0, instances=1)¶

Transform vertices. Stores the output in a single buffer. The transform primitive (mode) must be the same as the input primitive of the GeometryShader.

Keyword Arguments:
Parameters:	buffer (Buffer) – The buffer to store the output. mode (int) – By default `POINTS` will be used. vertices (int) – The number of vertices to transform.
	first (int) – The index of the first vertex to start with. instances (int) – The number of instances.

VertexArray.bind(attribute, cls, buffer, fmt, offset=0, stride=0, divisor=0, normalize=False)¶

Bind individual attributes to buffers.

Keyword Arguments:
Parameters:	location (int) – The attribute location. cls (str) – The attribute class. Valid values are `f`, `i` or `d`. buffer (Buffer) – The buffer. format (str) – The buffer format.
	offset (int) – The offset. stride (int) – The stride. divisor (int) – The divisor. normalize (bool) – The normalize parameter, if applicable.

Attributes¶

VertexArray.program¶

The program assinged to the VertexArray. The program used when rendering or transforming primitives.

Type:	Program

VertexArray.index_buffer¶

The index buffer if the index_buffer is set, otherwise None.

Type:	Buffer

VertexArray.index_element_size¶

The byte size of each element in the index buffer

Type:	int

VertexArray.vertices¶

The number of vertices detected. This is the minimum of the number of vertices possible per Buffer. The size of the index_buffer determines the number of vertices. Per instance vertex attributes does not affect this number.

Type:	int

VertexArray.subroutines¶

The subroutines assinged to the VertexArray. The subroutines used when rendering or transforming primitives.

Type:	tuple

VertexArray.glo¶

The internal OpenGL object. This values is provided for debug purposes only.

Type:	int

VertexArray.extra¶: Any - Attribute for storing user defined objects

Program¶

class moderngl.Program¶

A Program object represents fully processed executable code in the OpenGL Shading Language, for one or more Shader stages.

In ModernGL, a Program object can be assigned to VertexArray objects. The VertexArray object is capable of binding the Program object once the VertexArray.render() or VertexArray.transform() is called.

Program objects has no method called use(), VertexArrays encapsulate this mechanism.

A Program object cannot be instantiated directly, it requires a context. Use Context.program() to create one.

Create¶

Context.program(vertex_shader, fragment_shader=None, geometry_shader=None, tess_control_shader=None, tess_evaluation_shader=None, varyings=()) → Program

Create a Program object.

Only linked programs will be returned.

A single shader in the shaders parameter is also accepted. The varyings are only used when a transform program is created.

Parameters:	shaders (list) – A list of `Shader` objects. varyings (list) – A list of varying names.
Returns:	`Program` object

Methods¶

Program.get(key, default) → Union[Uniform, UniformBlock, Subroutine, Attribute, Varying]¶

Returns a Uniform, UniformBlock, Subroutine, Attribute or Varying.

Parameters:	default – This is the value to be returned in case key does not exist.
Returns:	`Uniform`, `UniformBlock`, `Subroutine`, `Attribute` or `Varying`

Attributes¶

Program.geometry_input¶

The geometry input primitive. The GeometryShader’s input primitive if the GeometryShader exists. The geometry input primitive will be used for validation.

Type:	int

Program.geometry_output¶

The geometry output primitive. The GeometryShader’s output primitive if the GeometryShader exists.

Type:	int

Program.geometry_vertices¶

The maximum number of vertices that the geometry shader will output.

Type:	int

Program.subroutines¶

The subroutine uniforms.

Type:	tuple

Program.glo¶

The internal OpenGL object. This values is provided for debug purposes only.

Type:	int

Program.extra¶: Any - Attribute for storing user defined objects

Examples¶

A simple program designed for rendering

my_render_program = ctx.program(
    vertex_shader='''
        #version 330

        in vec2 vert;

        void main() {
            gl_Position = vec4(vert, 0.0, 1.0);
        }
    ''',
    fragment_shader='''
        #version 330

        out vec4 color;

        void main() {
            color = vec4(0.3, 0.5, 1.0, 1.0);
        }
    ''',
)

A simple program designed for transforming

my_transform_program = ctx.program(
    vertex_shader='''
        #version 330

        in vec4 vert;
        out float vert_length;

        void main() {
            vert_length = length(vert);
        }
    ''',
    varyings=['vert_length']
)

Program Members¶

Uniform¶

class moderngl.Uniform¶

A uniform is a global GLSL variable declared with the “uniform” storage qualifier. These act as parameters that the user of a shader program can pass to that program.

In ModernGL, Uniforms can be accessed using Program.uniforms

Methods¶

Uniform.read() → bytes¶: Read the value of the uniform.

Uniform.write(data)¶: Write the value of the uniform.

Attributes¶

Uniform.location¶

The location of the uniform. The location holds the value returned by the glGetUniformLocation. To set the value of the uniform use the value instead.

Type:	int

Uniform.dimension¶

The dimension of the uniform.

GLSL type	dimension
sampler2D	1
sampler2DCube	1
sampler2DShadow	1
bool	1
bvec2	2
bvec3	3
bvec4	4
int	1
ivec2	2
ivec3	3
ivec4	4
uint	1
uvec2	2
uvec3	3
uvec4	4
float	1
vec2	2
vec3	3
vec4	4
double	1
dvec2	2
dvec3	3
dvec4	4
mat2	4
mat2x3	6
mat2x4	8
mat3x2	6
mat3	9
mat3x4	12
mat4x2	8
mat4x3	12
mat4	16
dmat2	4
dmat2x3	6
dmat2x4	8
dmat3x2	6
dmat3	9
dmat3x4	12
dmat4x2	8
dmat4x3	12
dmat4	16

Type:	int

Uniform.array_length¶

The length of the array of the uniform. The array_length is 1 for non array uniforms.

Type:	int

Uniform.name¶

The name of the uniform. The name does not contain leading [0]. The name may contain [ ] when the uniform is part of a struct.

Type:	str

Uniform.value¶

The value of the uniform. Reading the value of the uniform may force the GPU to sync.

The value must be a tuple for non array uniforms. The value must be a list of tuples for array uniforms.

Uniform.extra¶: Any - Attribute for storing user defined objects

UniformBlock¶

class moderngl.UniformBlock¶

UniformBlock.binding¶

The binding of the uniform block.

Type:	int

UniformBlock.name¶

The name of the uniform block.

Type:	str

UniformBlock.index¶

The index of the uniform block.

Type:	int

UniformBlock.size¶

The size of the uniform block.

Type:	int

UniformBlock.extra¶: Any - Attribute for storing user defined objects

Subroutine¶

class moderngl.Subroutine¶: This class represents a program subroutine.

Subroutine.index¶

The index of the subroutine.

Type:	int

Subroutine.name¶

The name of the subroutine.

Type:	str

Subroutine.extra¶: Any - Attribute for storing user defined objects

Attribute¶

class moderngl.Attribute¶: This class represents a program attribute.

Attribute.location¶

The location of the attribute. The result of the glGetAttribLocation.

Type:	int

Attribute.array_length¶

If the attribute is an array the array_length is the length of the array otherwise 1.

Type:	int

Attribute.dimension¶

The attribute dimension.

GLSL type	dimension
int	1
ivec2	2
ivec3	3
ivec4	4
uint	1
uvec2	2
uvec3	3
uvec4	4
float	1
vec2	2
vec3	3
vec4	4
double	1
dvec2	2
dvec3	3
dvec4	4
mat2	4
mat2x3	6
mat2x4	8
mat3x2	6
mat3	9
mat3x4	12
mat4x2	8
mat4x3	12
mat4	16
dmat2	4
dmat2x3	6
dmat2x4	8
dmat3x2	6
dmat3	9
dmat3x4	12
dmat4x2	8
dmat4x3	12
dmat4	16

Type:	int

Attribute.shape¶

The shape is a single character, representing the scalar type of the attriute.

shape	GLSL types
`'i'`	int
`'i'`	ivec2 ivec3 ivec4
`'I'`	uint
`'I'`	uvec2 uvec3 uvec4
`'f'`	float
	vec2 vec3 vec4
	mat2 mat3 mat4
	mat2x3 mat2x4 mat3x4 mat4x2 mat4x2 mat4x3
`'d'`	double
	dvec2 dvec3 dvec4
	dmat2 dmat3 dmat4
	dmat2x3 dmat2x4 dmat3x4 dmat4x2 dmat4x2 dmat4x3

Type:	str

Attribute.name¶

The attribute name. The name will be filtered to have no array syntax on it’s end. Attribute name without '[0]' ending if any.

Type:	str

Attribute.extra¶: Any - Attribute for storing user defined objects

Varying¶

class moderngl.Varying¶: This class represents a program varying.

Varying.name¶

The name of the varying.

Type:	str

Varying.number¶

The number of the varying.

Type:	int

Varying.extra¶: Any - Attribute for storing user defined objects

Sampler¶

class moderngl.Sampler¶

A Sampler Object is an OpenGL Object that stores the sampling parameters for a Texture access inside of a shader. When a sampler object is bound to a texture image unit, the internal sampling parameters for a texture bound to the same image unit are all ignored. Instead, the sampling parameters are taken from this sampler object.

Unlike textures, a samplers state can also be changed freely be at any time without the sampler object being bound/in use.

Samplers are bound to a texture unit and not a texture itself. Be careful with leaving samplers bound to texture units as it can cause texture incompletness issues (the texture bind is ignored).

Sampler bindings do clear automatically between every frame so a texture unit need at least one bind/use per frame.

Create¶

Context.sampler(repeat_x=True, repeat_y=True, repeat_z=True, filter=None, anisotropy=1.0, compare_func='?', border_color=None, min_lod=-1000.0, max_lod=1000.0) → Sampler¶

Create a Sampler object.

Keyword Arguments:

repeat_x (bool) – Repeat texture on x
repeat_y (bool) – Repeat texture on y
repeat_z (bool) – Repeat texture on z
filter (tuple) – The min and max filter
anisotropy (float) – Number of samples for anisotropic filtering. Any value greater than 1.0 counts as a use of anisotropic filtering
compare_func – Compare function for depth textures
border_color (tuple) – The (r, g, b, a) color for the texture border. When this value is set the repeat_ values are overriden setting the texture wrap to return the border color when outside [0, 1] range.
min_lod (float) – Minimum level-of-detail parameter (Default -1000.0). This floating-point value limits the selection of highest resolution mipmap (lowest mipmap level)
max_lod (float) – Minimum level-of-detail parameter (Default 1000.0). This floating-point value limits the selection of the lowest resolution mipmap (highest mipmap level)

Methods¶

Sampler.use(location=0)¶

Bind the sampler to a texture unit

Parameters:	location (int) – The texture unit

Sampler.clear(location=0)¶

Clear the sampler binding on a texture unit

Parameters:	location (int) – The texture unit

Sampler.release()¶: Release/destroy the ModernGL object.

Attributes¶

Sampler.repeat_x¶

The x repeat flag for the sampler (Default True)

Example:

# Enable texture repeat (GL_REPEAT)
sampler.repeat_x = True

# Disable texture repeat (GL_CLAMP_TO_EDGE)
sampler.repeat_x = False

Type:	bool

Sampler.repeat_y¶

The y repeat flag for the sampler (Default True)

Example:

# Enable texture repeat (GL_REPEAT)
sampler.repeat_y = True

# Disable texture repeat (GL_CLAMP_TO_EDGE)
sampler.repeat_y = False

Type:	bool

Sampler.repeat_z¶

The z repeat flag for the sampler (Default True)

Example:

# Enable texture repeat (GL_REPEAT)
sampler.repeat_z = True

# Disable texture repeat (GL_CLAMP_TO_EDGE)
sampler.repeat_z = False

Type:	bool

Sampler.filter¶

The minification and magnification filter for the sampler. (Default (moderngl.LINEAR. moderngl.LINEAR))

Example:

sampler.filter == (monderngl.NEAREST, moderngl.NEAREST)
sampler.filter == (monderngl.LINEAR_MIPMAP_LINEAR, moderngl.LINEAR)
sampler.filter == (monderngl.NEAREST_MIPMAP_LINEAR, moderngl.NEAREST)
sampler.filter == (monderngl.LINEAR_MIPMAP_NEAREST, moderngl.NEAREST)

Type:	tuple

Sampler.compare_func¶

The compare function for a depth textures (Default '?')

By default samplers don’t have depth comparison mode enabled. This means that depth texture values can be read as a sampler2D using texture() in a GLSL shader by default.

When setting this property to a valid compare mode, GL_TEXTURE_COMPARE_MODE is set to GL_COMPARE_REF_TO_TEXTURE so that texture lookup functions in GLSL will return a depth comparison result instead of the actual depth value.

Accepted compare functions:

.compare_func = ''    # Disale depth comparison completely
sampler.compare_func = '<='  # GL_LEQUAL
sampler.compare_func = '<'   # GL_LESS
sampler.compare_func = '>='  # GL_GEQUAL
sampler.compare_func = '>'   # GL_GREATER
sampler.compare_func = '=='  # GL_EQUAL
sampler.compare_func = '!='  # GL_NOTEQUAL
sampler.compare_func = '0'   # GL_NEVER
sampler.compare_func = '1'   # GL_ALWAYS

Type:	tuple

Sampler.anisotropy¶

Number of samples for anisotropic filtering (Default 1.0). The value will be clamped in range 1.0 and ctx.max_anisotropy.

Any value greater than 1.0 counts as a use of anisotropic filtering:

# Disable anisotropic filtering
sampler.anisotropy = 1.0

# Enable anisotropic filtering suggesting 16 samples as a maximum
sampler.anisotropy = 16.0

Type:	float

Sampler.border_color¶

When setting this value the repeat_ values are overriden setting the texture wrap to return the border color when outside [0, 1] range.

Example:

# Red border color
sampler.border_color = (1.0, 0.0, 0.0, 0.0)

Sampler.min_lod¶

Minimum level-of-detail parameter (Default -1000.0). This floating-point value limits the selection of highest resolution mipmap (lowest mipmap level)

Type:	float

Sampler.max_lod¶

Minimum level-of-detail parameter (Default 1000.0). This floating-point value limits the selection of the lowest resolution mipmap (highest mipmap level)

Type:	float

Sampler.extra¶: Any - Attribute for storing user defined objects

Texture¶

class moderngl.Texture¶

A Texture is an OpenGL object that contains one or more images that all have the same image format. A texture can be used in two ways. It can be the source of a texture access from a Shader, or it can be used as a render target.

A Texture object cannot be instantiated directly, it requires a context. Use Context.texture() or Context.depth_texture() to create one.

Create¶

Context.texture(size, components, data=None, samples=0, alignment=1, dtype='f1') → Texture

Create a Texture object.

Keyword Arguments:
Parameters:	size (tuple) – The width and height of the texture. components (int) – The number of components 1, 2, 3 or 4. data (bytes) – Content of the texture.
	samples (int) – The number of samples. Value 0 means no multisample format. alignment (int) – The byte alignment 1, 2, 4 or 8. dtype (str) – Data type.
Returns:	`Texture` object

Context.depth_texture(size, data=None, samples=0, alignment=4) → Texture

Create a Texture object.

Keyword Arguments:
Parameters:	size (tuple) – The width and height of the texture. data (bytes) – Content of the texture.
	samples (int) – The number of samples. Value 0 means no multisample format. alignment (int) – The byte alignment 1, 2, 4 or 8.
Returns:	`Texture` object

Methods¶

Texture.read(level=0, alignment=1) → bytes¶

Read the content of the texture into a buffer.

Keyword Arguments:
	level (int) – The mipmap level. alignment (int) – The byte alignment of the pixels.
Returns:	bytes

Texture.read_into(buffer, level=0, alignment=1, write_offset=0)¶

Read the content of the texture into a buffer.

Keyword Arguments:
Parameters:	buffer (bytearray) – The buffer that will receive the pixels.
	level (int) – The mipmap level. alignment (int) – The byte alignment of the pixels. write_offset (int) – The write offset.

Texture.write(data, viewport=None, level=0, alignment=1)¶

Update the content of the texture.

Keyword Arguments:
Parameters:	data (bytes) – The pixel data. viewport (tuple) – The viewport.
	level (int) – The mipmap level. alignment (int) – The byte alignment of the pixels.

Texture.build_mipmaps(base=0, max_level=1000)¶

Generate mipmaps.

This also changes the texture filter to LINEAR_MIPMAP_LINEAR, LINEAR (Will be removed in 6.x)

Keyword Arguments:
	base (int) – The base level max_level (int) – The maximum levels to generate

Texture.use(location=0)¶

Bind the texture.

Parameters:	location (int) – The texture location. Same as the integer value that is used for sampler2D uniforms in the shaders. The value `0` will bind the texture to the `GL_TEXTURE0` binding point.

Attributes¶

Texture.repeat_x¶

The x repeat flag for the texture (Default True)

Example:

# Enable texture repeat (GL_REPEAT)
texture.repeat_x = True

# Disable texture repeat (GL_CLAMP_TO_EDGE)
texture.repeat_x = False

Type:	bool

Texture.repeat_y¶

The y repeat flag for the texture (Default True)

Example:

# Enable texture repeat (GL_REPEAT)
texture.repeat_y = True

# Disable texture repeat (GL_CLAMP_TO_EDGE)
texture.repeat_y = False

Type:	bool

Texture.filter¶

The minification and magnification filter for the texture. (Default (moderngl.LINEAR. moderngl.LINEAR))

Example:

texture.filter == (monderngl.NEAREST, moderngl.NEAREST)
texture.filter == (monderngl.LINEAR_MIPMAP_LINEAR, moderngl.LINEAR)
texture.filter == (monderngl.NEAREST_MIPMAP_LINEAR, moderngl.NEAREST)
texture.filter == (monderngl.LINEAR_MIPMAP_NEAREST, moderngl.NEAREST)

Type:	tuple

Texture.swizzle¶

The swizzle mask of the texture (Default 'RGBA').

The swizzle mask change/reorder the vec4 value returned by the texture() function in a GLSL shaders. This is represented by a 4 character string were each character can be:

'R' GL_RED
'G' GL_GREEN
'B' GL_BLUE
'A' GL_ALPHA
'0' GL_ZERO
'1' GL_ONE

Example:

# Alpha channel will always return 1.0
texture.swizzle = 'RGB1'

# Only return the red component. The rest is masked to 0.0
texture.swizzle = 'R000'

# Reverse the components
texture.swizzle = 'ABGR'

Type:	str

Texture.compare_func¶

The compare function of the depth texture (Default '<=')

By default depth textures have GL_TEXTURE_COMPARE_MODE set to GL_COMPARE_REF_TO_TEXTURE, meaning any texture lookup will return a depth comparison value.

If you need to read the actual depth value in shaders, setting compare_func to a blank string will set GL_TEXTURE_COMPARE_MODE to GL_NONE making you able to read the depth texture as a sampler2D:

uniform sampler2D depth;
out vec4 fragColor;
in vec2 uv;

void main() {
    float raw_depth_nonlinear = texture(depth, uv);
    fragColor = vec4(raw_depth_nonlinear);
}

Accepted compare functions:

texture.compare_func = ''    # Disale depth comparison completely
texture.compare_func = '<='  # GL_LEQUAL
texture.compare_func = '<'   # GL_LESS
texture.compare_func = '>='  # GL_GEQUAL
texture.compare_func = '>'   # GL_GREATER
texture.compare_func = '=='  # GL_EQUAL
texture.compare_func = '!='  # GL_NOTEQUAL
texture.compare_func = '0'   # GL_NEVER
texture.compare_func = '1'   # GL_ALWAYS

Type:	tuple

Texture.anisotropy¶

Number of samples for anisotropic filtering (Default 1.0). The value will be clamped in range 1.0 and ctx.max_anisotropy.

Any value greater than 1.0 counts as a use of anisotropic filtering:

# Disable anisotropic filtering
texture.anisotropy = 1.0

# Enable anisotropic filtering suggesting 16 samples as a maximum
texture.anisotropy = 16.0

Type:	float

Texture.width¶

The width of the texture.

Type:	int

Texture.height¶

The height of the texture.

Type:	int

Texture.size¶

The size of the texture.

Type:	tuple

Texture.dtype¶

Data type.

Type:	str

Texture.components¶

The number of components of the texture.

Type:	int

Texture.samples¶

The number of samples set for the texture used in multisampling.

Type:	int

Texture.depth¶

Is the texture a depth texture?

Type:	bool

Texture.glo¶

The internal OpenGL object. This values is provided for debug purposes only.

Type:	int

Texture.extra¶: Any - Attribute for storing user defined objects

TextureArray¶

class moderngl.TextureArray¶

An Array Texture is a Texture where each mipmap level contains an array of images of the same size. Array textures may have Mipmaps, but each mipmap in the texture has the same number of levels.

A TextureArray object cannot be instantiated directly, it requires a context. Use Context.texture_array() to create one.

Create¶

Context.texture_array(size, components, data=None, alignment=1, dtype='f1') → TextureArray

Create a TextureArray object.

Keyword Arguments:
Parameters:	size (tuple) – The `(width, height, layers)` of the texture. components (int) – The number of components 1, 2, 3 or 4. data (bytes) – Content of the texture. The size must be `(width, height * layers)` so each layer is stacked vertically.
	alignment (int) – The byte alignment 1, 2, 4 or 8. dtype (str) – Data type.
Returns:	`Texture3D` object

Methods¶

TextureArray.read(alignment=1) → bytes¶

Read the content of the texture array into a buffer.

Keyword Arguments:
	alignment (int) – The byte alignment of the pixels.
Returns:	bytes

TextureArray.read_into(buffer, alignment=1, write_offset=0)¶

Read the content of the texture array into a buffer.

Keyword Arguments:
Parameters:	buffer (bytearray) – The buffer that will receive the pixels.
	alignment (int) – The byte alignment of the pixels. write_offset (int) – The write offset.

TextureArray.write(data, viewport=None, alignment=1)¶

Update the content of the texture array.

Keyword Arguments:
Parameters:	data (bytes) – The pixel data. viewport (tuple) – The viewport.
	alignment (int) – The byte alignment of the pixels.

TextureArray.build_mipmaps(base=0, max_level=1000)¶

Generate mipmaps.

This also changes the texture filter to LINEAR_MIPMAP_LINEAR, LINEAR (Will be removed in 6.x)

Keyword Arguments:
	base (int) – The base level max_level (int) – The maximum levels to generate

TextureArray.use(location=0)¶

Bind the texture array.

Parameters:	location (int) – The texture location. Same as the integer value that is used for sampler2D uniforms in the shaders. The value `0` will bind the texture to the `GL_TEXTURE0` binding point.

Attributes¶

TextureArray.repeat_x¶

The x repeat flag for the texture (Default True)

Example:

# Enable texture repeat (GL_REPEAT)
texture.repeat_x = True

# Disable texture repeat (GL_CLAMP_TO_EDGE)
texture.repeat_x = False

Type:	bool

TextureArray.repeat_y¶

The y repeat flag for the texture (Default True)

Example:

# Enable texture repeat (GL_REPEAT)
texture.repeat_y = True

# Disable texture repeat (GL_CLAMP_TO_EDGE)
texture.repeat_y = False

Type:	bool

TextureArray.filter¶

The minification and magnification filter for the texture. (Default (moderngl.LINEAR. moderngl.LINEAR))

Example:

texture.filter == (monderngl.NEAREST, moderngl.NEAREST)
texture.filter == (monderngl.LINEAR_MIPMAP_LINEAR, moderngl.LINEAR)
texture.filter == (monderngl.NEAREST_MIPMAP_LINEAR, moderngl.NEAREST)
texture.filter == (monderngl.LINEAR_MIPMAP_NEAREST, moderngl.NEAREST)

Type:	tuple

TextureArray.swizzle¶

The swizzle mask of the texture (Default 'RGBA').

The swizzle mask change/reorder the vec4 value returned by the texture() function in a GLSL shaders. This is represented by a 4 character string were each character can be:

'R' GL_RED
'G' GL_GREEN
'B' GL_BLUE
'A' GL_ALPHA
'0' GL_ZERO
'1' GL_ONE

Example:

# Alpha channel will always return 1.0
texture.swizzle = 'RGB1'

# Only return the red component. The rest is masked to 0.0
texture.swizzle = 'R000'

# Reverse the components
texture.swizzle = 'ABGR'

Type:	str

TextureArray.anisotropy¶

Number of samples for anisotropic filtering (Default 1.0). The value will be clamped in range 1.0 and ctx.max_anisotropy.

Any value greater than 1.0 counts as a use of anisotropic filtering:

# Disable anisotropic filtering
texture.anisotropy = 1.0

# Enable anisotropic filtering suggesting 16 samples as a maximum
texture.anisotropy = 16.0

Type:	float

TextureArray.width¶

The width of the texture array.

Type:	int

TextureArray.height¶

The height of the texture array.

Type:	int

TextureArray.layers¶

The number of layers of the texture array.

Type:	int

TextureArray.size¶

The size of the texture array.

Type:	tuple

TextureArray.dtype¶

Data type.

Type:	str

TextureArray.components¶

The number of components of the texture array.

Type:	int

TextureArray.glo¶

The internal OpenGL object. This values is provided for debug purposes only.

Type:	int

TextureArray.extra¶: Any - Attribute for storing user defined objects

Texture3D¶

class moderngl.Texture3D¶

A Texture is an OpenGL object that contains one or more images that all have the same image format. A texture can be used in two ways. It can be the source of a texture access from a Shader, or it can be used as a render target.

A Texture3D object cannot be instantiated directly, it requires a context. Use Context.texture3d() to create one.

Create¶

Context.texture3d(size, components, data=None, alignment=1, dtype='f1') → Texture3D

Create a Texture3D object.

Keyword Arguments:
Parameters:	size (tuple) – The width, height and depth of the texture. components (int) – The number of components 1, 2, 3 or 4. data (bytes) – Content of the texture.
	alignment (int) – The byte alignment 1, 2, 4 or 8. dtype (str) – Data type.
Returns:	`Texture3D` object

Methods¶

Texture3D.read(alignment=1) → bytes¶

Read the content of the texture into a buffer.

Keyword Arguments:
	alignment (int) – The byte alignment of the pixels.
Returns:	bytes

Texture3D.read_into(buffer, alignment=1, write_offset=0)¶

Read the content of the texture into a buffer.

Keyword Arguments:
Parameters:	buffer (bytearray) – The buffer that will receive the pixels.
	alignment (int) – The byte alignment of the pixels. write_offset (int) – The write offset.

Texture3D.write(data, viewport=None, alignment=1)¶

Update the content of the texture.

Keyword Arguments:
Parameters:	data (bytes) – The pixel data. viewport (tuple) – The viewport.
	alignment (int) – The byte alignment of the pixels.

Texture3D.build_mipmaps(base=0, max_level=1000)¶

Generate mipmaps.

This also changes the texture filter to LINEAR_MIPMAP_LINEAR, LINEAR (Will be removed in 6.x)

Keyword Arguments:
	base (int) – The base level max_level (int) – The maximum levels to generate

Texture3D.use(location=0)¶

Bind the texture.

Parameters:	location (int) – The texture location. Same as the integer value that is used for sampler3D uniforms in the shaders. The value `0` will bind the texture to the `GL_TEXTURE0` binding point.

Attributes¶

Texture3D.repeat_x¶

The x repeat flag for the texture (Default True)

Example:

# Enable texture repeat (GL_REPEAT)
texture.repeat_x = True

# Disable texture repeat (GL_CLAMP_TO_EDGE)
texture.repeat_x = False

Type:	bool

Texture3D.repeat_y¶

The y repeat flag for the texture (Default True)

Example:

# Enable texture repeat (GL_REPEAT)
texture.repeat_y = True

# Disable texture repeat (GL_CLAMP_TO_EDGE)
texture.repeat_y = False

Type:	bool

Texture3D.repeat_z¶

The z repeat flag for the texture (Default True)

Example:

# Enable texture repeat (GL_REPEAT)
texture.repeat_z = True

# Disable texture repeat (GL_CLAMP_TO_EDGE)
texture.repeat_z = False

Type:	bool

Texture3D.filter¶

The filter of the texture.

Type:	tuple

Texture3D.swizzle¶

The swizzle mask of the texture (Default 'RGBA').

The swizzle mask change/reorder the vec4 value returned by the texture() function in a GLSL shaders. This is represented by a 4 character string were each character can be:

'R' GL_RED
'G' GL_GREEN
'B' GL_BLUE
'A' GL_ALPHA
'0' GL_ZERO
'1' GL_ONE

Example:

# Alpha channel will always return 1.0
texture.swizzle = 'RGB1'

# Only return the red component. The rest is masked to 0.0
texture.swizzle = 'R000'

# Reverse the components
texture.swizzle = 'ABGR'

Type:	str

Texture3D.width¶

The width of the texture.

Type:	int

Texture3D.height¶

The height of the texture.

Type:	int

Texture3D.depth¶

The depth of the texture.

Type:	int

Texture3D.size¶

The size of the texture.

Type:	tuple

Texture3D.dtype¶

Data type.

Type:	str

Texture3D.components¶

The number of components of the texture.

Type:	int

Texture3D.glo¶

The internal OpenGL object. This values is provided for debug purposes only.

Type:	int

Texture3D.extra¶: Any - Attribute for storing user defined objects

TextureCube¶

class moderngl.TextureCube¶

A Texture is an OpenGL object that contains one or more images that all have the same image format. A texture can be used in two ways. It can be the source of a texture access from a Shader, or it can be used as a render target.

A Texture3D object cannot be instantiated directly, it requires a context. Use Context.texture_cube() to create one.

Create¶

Context.texture_cube(size, components, data=None, alignment=1, dtype='f1') → TextureCube

Create a TextureCube object.

Keyword Arguments:
Parameters:	size (tuple) – The width, height of the texture. Each side of the cube will have this size. components (int) – The number of components 1, 2, 3 or 4. data (bytes) – Content of the texture.
	alignment (int) – The byte alignment 1, 2, 4 or 8. dtype (str) – Data type.
Returns:	`TextureCube` object

Methods¶

TextureCube.read(face, alignment=1) → bytes¶

Read a face from the cubemap texture.

Keyword Arguments:
Parameters:	face (int) – The face to read.
	alignment (int) – The byte alignment of the pixels.

TextureCube.read_into(buffer, face, alignment=1, write_offset=0)¶

Read a face from the cubemap texture.

Keyword Arguments:
Parameters:	buffer (bytearray) – The buffer that will receive the pixels. face (int) – The face to read.
	alignment (int) – The byte alignment of the pixels. write_offset (int) – The write offset.

TextureCube.write(face, data, viewport=None, alignment=1)¶

Update the content of the texture.

Keyword Arguments:
Parameters:	face (int) – The face to update. data (bytes) – The pixel data. viewport (tuple) – The viewport.
	alignment (int) – The byte alignment of the pixels.

TextureCube.use(location=0)¶

Bind the cubemap texture.

Parameters:	location (int) – The texture location. Same as the integer value that is used for sampler3D uniforms in the shaders. The value `0` will bind the texture to the `GL_TEXTURE0` binding point.

Attributes¶

TextureCube.size¶

The size of the texture.

Type:	tuple

TextureCube.dtype¶

Data type.

Type:	str

TextureCube.components¶

The number of components of the texture.

Type:	int

TextureCube.filter¶

The minification and magnification filter for the texture. (Default (moderngl.LINEAR. moderngl.LINEAR))

Example:

texture.filter == (monderngl.NEAREST, moderngl.NEAREST)
texture.filter == (monderngl.LINEAR_MIPMAP_LINEAR, moderngl.LINEAR)
texture.filter == (monderngl.NEAREST_MIPMAP_LINEAR, moderngl.NEAREST)
texture.filter == (monderngl.LINEAR_MIPMAP_NEAREST, moderngl.NEAREST)

Type:	tuple

TextureCube.swizzle¶

The swizzle mask of the texture (Default 'RGBA').

The swizzle mask change/reorder the vec4 value returned by the texture() function in a GLSL shaders. This is represented by a 4 character string were each character can be:

'R' GL_RED
'G' GL_GREEN
'B' GL_BLUE
'A' GL_ALPHA
'0' GL_ZERO
'1' GL_ONE

Example:

# Alpha channel will always return 1.0
texture.swizzle = 'RGB1'

# Only return the red component. The rest is masked to 0.0
texture.swizzle = 'R000'

# Reverse the components
texture.swizzle = 'ABGR'

Type:	str

TextureCube.anisotropy¶

Number of samples for anisotropic filtering (Default 1.0). The value will be clamped in range 1.0 and ctx.max_anisotropy.

Any value greater than 1.0 counts as a use of anisotropic filtering:

# Disable anisotropic filtering
texture.anisotropy = 1.0

# Enable anisotropic filtering suggesting 16 samples as a maximum
texture.anisotropy = 16.0

Type:	float

TextureCube.glo¶

The internal OpenGL object. This values is provided for debug purposes only.

Type:	int

TextureCube.extra¶: Any - Attribute for storing user defined objects

Framebuffer¶

class moderngl.Framebuffer¶

A Framebuffer is a collection of buffers that can be used as the destination for rendering. The buffers for Framebuffer objects reference images from either Textures or Renderbuffers.

Create a Framebuffer using Context.framebuffer().

Create¶

Context.simple_framebuffer(size, components=4, samples=0, dtype='f1') → Framebuffer

A Framebuffer is a collection of buffers that can be used as the destination for rendering. The buffers for Framebuffer objects reference images from either Textures or Renderbuffers.

Keyword Arguments:
Parameters:	size (tuple) – The width and height of the renderbuffer. components (int) – The number of components 1, 2, 3 or 4.
	samples (int) – The number of samples. Value 0 means no multisample format. dtype (str) – Data type.
Returns:	`Framebuffer` object

Context.framebuffer(color_attachments=(), depth_attachment=None) → Framebuffer

A Framebuffer is a collection of buffers that can be used as the destination for rendering. The buffers for Framebuffer objects reference images from either Textures or Renderbuffers.

Parameters:	color_attachments (list) – A list of `Texture` or `Renderbuffer` objects. depth_attachment (Renderbuffer or Texture) – The depth attachment.
Returns:	`Framebuffer` object

Methods¶

Framebuffer.clear(red=0.0, green=0.0, blue=0.0, alpha=0.0, depth=1.0, viewport=None)¶

Clear the framebuffer.

If the viewport is not None then scrissor test will be used to clear the given viewport.

If the viewport is a 2-tuple it will clear the (0, 0, width, height) where (width, height) is the 2-tuple.

If the viewport is a 4-tuple it will clear the given viewport.

Keyword Arguments:
Parameters:	red (float) – color component. green (float) – color component. blue (float) – color component. alpha (float) – alpha component. depth (float) – depth value.
	viewport (tuple) – The viewport.

Framebuffer.read(viewport=None, components=3, attachment=0, alignment=1, dtype='f1') → bytes¶

Read the content of the framebuffer.

Keyword Arguments:
Parameters:	viewport (tuple) – The viewport. components (int) – The number of components to read.
	attachment (int) – The color attachment. alignment (int) – The byte alignment of the pixels. dtype (str) – Data type.
Returns:	bytes

Framebuffer.read_into(buffer, viewport=None, components=3, attachment=0, alignment=1, dtype='f1', write_offset=0)¶

Read the content of the framebuffer into a buffer.

Keyword Arguments:
Parameters:	buffer (bytearray) – The buffer that will receive the pixels. viewport (tuple) – The viewport. components (int) – The number of components to read.
	attachment (int) – The color attachment. alignment (int) – The byte alignment of the pixels. dtype (str) – Data type. write_offset (int) – The write offset.

Framebuffer.use()¶: Bind the framebuffer. Set the target for the VertexArray.render().

Attributes¶

Framebuffer.viewport¶

The viewport of the framebuffer.

Type:	tuple

Framebuffer.color_mask¶

The color mask of the framebuffer.

Type:	tuple

Framebuffer.depth_mask¶

The depth mask of the framebuffer.

Type:	tuple

Framebuffer.width¶

The width of the framebuffer.

Type:	int

Framebuffer.height¶

The height of the framebuffer.

Type:	int

Framebuffer.size¶

The size of the framebuffer.

Type:	tuple

Framebuffer.samples¶

The samples of the framebuffer.

Type:	int

Framebuffer.bits¶

The bits of the framebuffer.

Type:	dict

Framebuffer.color_attachments¶

The color attachments of the framebuffer.

Type:	tuple

Framebuffer.depth_attachment¶

The depth attachment of the framebuffer.

Type:	Texture or Renderbuffer

Framebuffer.glo¶

The internal OpenGL object. This values is provided for debug purposes only.

Type:	int

Framebuffer.extra¶: Any - Attribute for storing user defined objects

Renderbuffer¶

class moderngl.Renderbuffer¶

Renderbuffer objects are OpenGL objects that contain images. They are created and used specifically with Framebuffer objects. They are optimized for use as render targets, while Texture objects may not be, and are the logical choice when you do not need to sample from the produced image. If you need to resample, use Textures instead. Renderbuffer objects also natively accommodate multisampling.

A Renderbuffer object cannot be instantiated directly, it requires a context. Use Context.renderbuffer() or Context.depth_renderbuffer() to create one.

Create¶

Context.renderbuffer(size, components=4, samples=0, dtype='f1') → Renderbuffer

Renderbuffer objects are OpenGL objects that contain images. They are created and used specifically with Framebuffer objects.

Keyword Arguments:
Parameters:	size (tuple) – The width and height of the renderbuffer. components (int) – The number of components 1, 2, 3 or 4.
	samples (int) – The number of samples. Value 0 means no multisample format. dtype (str) – Data type.
Returns:	`Renderbuffer` object

Context.depth_renderbuffer(size, samples=0) → Renderbuffer

Renderbuffer objects are OpenGL objects that contain images. They are created and used specifically with Framebuffer objects.

Keyword Arguments:
Parameters:	size (tuple) – The width and height of the renderbuffer.
	samples (int) – The number of samples. Value 0 means no multisample format.
Returns:	`Renderbuffer` object

Attributes¶

Renderbuffer.width¶

The width of the renderbuffer.

Type:	int

Renderbuffer.height¶

The height of the renderbuffer.

Type:	int

Renderbuffer.size¶

The size of the renderbuffer.

Type:	tuple

Renderbuffer.samples¶

The samples of the renderbuffer.

Type:	int

Renderbuffer.components¶

The components of the renderbuffer.

Type:	int

Renderbuffer.depth¶

Is the renderbuffer a depth renderbuffer?

Type:	bool

Renderbuffer.dtype¶

Data type.

Type:	str

Renderbuffer.glo¶

The internal OpenGL object. This values is provided for debug purposes only.

Type:	int

Renderbuffer.extra¶: Any - Attribute for storing user defined objects

Scope¶

class moderngl.Scope¶

This class represents a Scope object.

Responsibilities on enter:

Set the enable flags.
Bind the framebuffer.
Assigning textures to texture locations.
Assigning buffers to uniform buffers.
Assigning buffers to shader storage buffers.

Responsibilities on exit:

Restore the enable flags.
Restore the framebuffer.

Create¶

Context.scope(framebuffer, enable_only=None, textures=(), uniform_buffers=(), storage_buffers=()) → Scope

Create a Scope object.

Keyword Arguments:
Parameters:	framebuffer (Framebuffer) – The framebuffer to use when entering. enable_only (int) – The enable_only flags to set when entering.
	textures (list) – List of (texture, binding) tuples. uniform_buffers (list) – List of (buffer, binding) tuples. storage_buffers (list) – List of (buffer, binding) tuples.

Attributes¶

Scope.extra¶: Any - Attribute for storing user defined objects

Examples¶

Simple scope example

scope1 = ctx.scope(fbo1, moderngl.BLEND)
scope2 = ctx.scope(fbo2, moderngl.DEPTH_TEST | moderngl.CULL_FACE)

with scope1:
    # do some rendering

with scope2:
    # do some rendering

Scope for querying

query = ctx.query(samples=True)
scope = ctx.scope(ctx.screen, moderngl.DEPTH_TEST | moderngl.RASTERIZER_DISCARD)

with scope, query:
    # do some rendering

print(query.samples)

Understanding what scope objects do

scope = ctx.scope(
    framebuffer=framebuffer1,
    enable_only=moderngl.BLEND,
    textures=[
        (texture1, 4),
        (texture2, 3),
    ],
    uniform_buffers=[
        (buffer1, 6),
        (buffer2, 5),
    ],
    storage_buffers=[
        (buffer3, 8),
    ],
)

# Let's assume we have some state before entering the scope
some_random_framebuffer.use()
some_random_texture.use(3)
some_random_buffer.bind_to_uniform_block(5)
some_random_buffer.bind_to_storage_buffer(8)
ctx.enable_only(moderngl.DEPTH_TEST)

with scope:
    # on __enter__
    #     framebuffer1.use()
    #     ctx.enable_only(moderngl.BLEND)
    #     texture1.use(4)
    #     texture2.use(3)
    #     buffer1.bind_to_uniform_block(6)
    #     buffer2.bind_to_uniform_block(5)
    #     buffer3.bind_to_storage_buffer(8)

    # do some rendering

    # on __exit__
    #     some_random_framebuffer.use()
    #     ctx.enable_only(moderngl.DEPTH_TEST)

# Originally we had the following, let's see what was changed
some_random_framebuffer.use()                 # This was restored hurray!
some_random_texture.use(3)                    # Have to restore it manually.
some_random_buffer.bind_to_uniform_block(5)   # Have to restore it manually.
some_random_buffer.bind_to_storage_buffer(8)  # Have to restore it manually.
ctx.enable_only(moderngl.DEPTH_TEST)          # This was restored too.

# Scope objects only do as much as necessary.
# Restoring the framebuffer and enable flags are lowcost operations and
# without them you could get a hard time debugging the application.

Query¶

class moderngl.Query¶: This class represents a Query object.

Create¶

Context.query(samples=False, any_samples=False, time=False, primitives=False) → Query

Create a Query object.

Keyword Arguments:
	samples (bool) – Query `GL_SAMPLES_PASSED` or not. any_samples (bool) – Query `GL_ANY_SAMPLES_PASSED` or not. time (bool) – Query `GL_TIME_ELAPSED` or not. primitives (bool) – Query `GL_PRIMITIVES_GENERATED` or not.

Attributes¶

Query.samples¶

The number of samples passed.

Type:	int

Query.primitives¶

The number of primitives generated.

Type:	int

Query.elapsed¶

The time elapsed in nanoseconds.

Type:	int

Query.crender¶

Can be used in a with statement.

Type:	ConditionalRender

Query.extra¶: Any - Attribute for storing user defined objects

Examples¶

Simple query example

import moderngl
import numpy as np

ctx = moderngl.create_standalone_context()
prog = ctx.program(
    vertex_shader='''
        #version 330

        in vec2 in_vert;

        void main() {
            gl_Position = vec4(in_vert, 0.0, 1.0);
        }
    ''',
    fragment_shader='''
        #version 330

        out vec4 color;

        void main() {
            color = vec4(1.0, 0.0, 0.0, 1.0);
        }
    ''',
)

vertices = np.array([
    0.0, 0.0,
    1.0, 0.0,
    0.0, 1.0,
], dtype='f4')

vbo = ctx.buffer(vertices.tobytes())
vao = ctx.simple_vertex_array(prog, vbo, 'in_vert')

fbo = ctx.simple_framebuffer((64, 64))
fbo.use()

query = ctx.query(samples=True, time=True)

with query:
    vao.render()

print('It took %d nanoseconds' % query.elapsed)
print('to render %d samples' % query.samples)

Output

It took 13529 nanoseconds
to render 496 samples

ConditionalRender¶

class moderngl.ConditionalRender¶

This class represents a ConditionalRender object.

ConditionalRender objects can only be accessed from Query objects.

Examples¶

Simple conditional rendering example

query = ctx.query(any_samples=True)

with query:
    vao1.render()

with query.crender:
    print('This will always get printed')
    vao2.render()  # But this will be rendered only if vao1 has passing samples.

ComputeShader¶

class moderngl.ComputeShader¶: A Compute Shader is a Shader Stage that is used entirely for computing arbitrary information. While it can do rendering, it is generally used for tasks not directly related to drawing.

Create¶

Context.compute_shader(source) → ComputeShader

A ComputeShader is a Shader Stage that is used entirely for computing arbitrary information. While it can do rendering, it is generally used for tasks not directly related to drawing.

Parameters:	source (str) – The source of the compute shader.
Returns:	`ComputeShader` object

Methods¶

ComputeShader.run(group_x=1, group_y=1, group_z=1)¶

Run the compute shader.

Parameters:	group_x (int) – The number of work groups to be launched in the X dimension. group_y (int) – The number of work groups to be launched in the Y dimension. group_z (int) – The number of work groups to be launched in the Z dimension.

ComputeShader.get(key, default) → Union[Uniform, UniformBlock, Subroutine, Attribute, Varying]¶

Returns a Uniform, UniformBlock, Subroutine, Attribute or Varying.

Parameters:	default – This is the value to be returned in case key does not exist.
Returns:	`Uniform`, `UniformBlock`, `Subroutine`, `Attribute` or `Varying`

Attributes¶

ComputeShader.source¶

The source code of the compute shader.

Type:	str

ComputeShader.glo¶

The internal OpenGL object. This values is provided for debug purposes only.

Type:	int

ComputeShader.extra¶: Any - Attribute for storing user defined objects

The Guide¶

A short introduction¶

What you will need?

To get something rendered, you will need a VertexArray.

VertexArrays can be created from a Program object and several Buffer objects.

To create a Program object, you will need some Shader objects.

Once you have your Program object, you can fill a Buffer with your data, then pass them to VertexArray, then call VertexArray.render().

All of the objects above can only be created from a Context object.

Here is our checklist:

Install ModernGL.
Create a Context.
Create a Program object.
Create a VertexArray object.

Proceede to the next step.

Install ModernGL¶

$ pip install --upgrade ModernGL

This tutorial will also use numpy to generate data and Pillow to save the final image.

$ pip install --upgrade numpy Pillow

Proceed to the next step.

Context¶

Let’s create a Standalone Context for now. It will help us write less code. Later you can reuse this code to render directly to a window.

import moderngl

ctx = moderngl.create_standalone_context()

Proceed to the next step.

Program¶

ModernGL is different from standard plotting libraries. You can define your own shader program to render stuff. This could complicate things, but also provides freedom on how you render your data.

Here is a sample program that passes the input vertex coordinates as is to screen coordinates.

Screen coordinates are in the [-1, 1], [-1, 1] range for x and y axes. The (-1, 1) point is the lower left corner of the screen.

The screen coordinates

The program will also process a color information.

Entire source

import moderngl

ctx = moderngl.create_standalone_context()

prog = ctx.program(
    vertex_shader='''
        #version 330

        in vec2 in_vert;
        in vec3 in_color;

        out vec3 v_color;

        void main() {
            v_color = in_color;
            gl_Position = vec4(in_vert, 0.0, 1.0);
        }
    ''',
    fragment_shader='''
        #version 330

        in vec3 v_color;

        out vec3 f_color;

        void main() {
            f_color = v_color;
        }
    ''',
)

Vertex Shader

in vec2 in_vert;
in vec3 in_color;

out vec3 v_color;

void main() {
    v_color = in_color;
    gl_Position = vec4(in_vert, 0.0, 1.0);
}

Fragment Shader

in vec3 v_color;

out vec3 f_color;

void main() {
    f_color = v_color;
}

Proceed to the next step.

VertexArray¶

import moderngl
import numpy as np

ctx = moderngl.create_standalone_context()

prog = ctx.program(
    vertex_shader='''
        #version 330

        in vec2 in_vert;
        in vec3 in_color;

        out vec3 v_color;

        void main() {
            v_color = in_color;
            gl_Position = vec4(in_vert, 0.0, 1.0);
        }
    ''',
    fragment_shader='''
        #version 330

        in vec3 v_color;

        out vec3 f_color;

        void main() {
            f_color = v_color;
        }
    ''',
)

x = np.linspace(-1.0, 1.0, 50)
y = np.random.rand(50) - 0.5
r = np.ones(50)
g = np.zeros(50)
b = np.zeros(50)

vertices = np.dstack([x, y, r, g, b])

vbo = ctx.buffer(vertices.astype('f4').tobytes())
vao = ctx.simple_vertex_array(prog, vbo, 'in_vert', 'in_color')

Proceed to the next step.

Rendering¶

import moderngl
import numpy as np

from PIL import Image

ctx = moderngl.create_standalone_context()

prog = ctx.program(
    vertex_shader='''
        #version 330

        in vec2 in_vert;
        in vec3 in_color;

        out vec3 v_color;

        void main() {
            v_color = in_color;
            gl_Position = vec4(in_vert, 0.0, 1.0);
        }
    ''',
    fragment_shader='''
        #version 330

        in vec3 v_color;

        out vec3 f_color;

        void main() {
            f_color = v_color;
        }
    ''',
)

x = np.linspace(-1.0, 1.0, 50)
y = np.random.rand(50) - 0.5
r = np.ones(50)
g = np.zeros(50)
b = np.zeros(50)

vertices = np.dstack([x, y, r, g, b])

vbo = ctx.buffer(vertices.astype('f4').tobytes())
vao = ctx.simple_vertex_array(prog, vbo, 'in_vert', 'in_color')

fbo = ctx.simple_framebuffer((512, 512))
fbo.use()
fbo.clear(0.0, 0.0, 0.0, 1.0)
vao.render(moderngl.LINE_STRIP)

Image.frombytes('RGB', fbo.size, fbo.read(), 'raw', 'RGB', 0, -1).show()

Miscellaneous¶

Differences between ModernGL5 and ModernGL4¶

Package Name¶

ModernGL4

import ModernGL  # mixed case

ModernGL5

import moderngl  # this is pep8 style

Program Creation¶

ModernGL4

my_program = ctx.program([  # extra list
    # vertex_shader returned a Shader object
    ctx.vertex_shader('''
        ...
    '''),
    # fragment_shader returned a Shader object
    ctx.fragment_shader('''
        ...
    '''),
])

ModernGL5

my_program = ctx.program(  # no list needed
    # vertex_shader is a keyword argument
    vertex_shader='''
        ...
    ''',
    # fragment_shader is a keyword argument
    fragment_shader='''
        ...
    ''',
)

Program Varyings¶

ModernGL4

my_program = ctx.program(
    ctx.vertex_shader('''
        ...
    '''),
    ['out_vert', 'out_norm']  # no keyword argument needed
])

ModernGL5

my_program = ctx.program(
    vertex_shader='''
        ...
    ''',
    varyings=['out_vert', 'out_norm'],  # varyings are explicitly given
)

Program Members¶

ModernGL4

my_program.uniforms['ModelViewMatrix'].value = ...
my_program.uniform_buffers['UniformBuffer'].binding = ...

ModernGL5

my_program['ModelViewMatrix'].value = ...
my_program['UniformBuffer'].binding = ...

Texture Pixel Types¶

ModernGL4

my_texture = ctx.texture(size, 4, floats=True)  # floats or not floats

ModernGL5

my_texture = ctx.texture(size, 4, dtype='f4')  # floats=True
my_texture = ctx.texture(size, 4, dtype='f2')  # half-floats
my_texture = ctx.texture(size, 4, dtype='f1')  # floats=False
my_texture = ctx.texture(size, 4, dtype='i4')  # integers

This also apply for Texture3D, TextureCube and Renderbuffer.

Buffer Format¶

ModernGL4

my_vertex_array = ctx.vertex_array(prog, [
    (vbo1, '3f3f', ['in_vert', 'in_norm']),  # extra list object
    #        ^ no space between the attributes
    ...
])

ModernGL5

my_vertex_array = ctx.vertex_array(prog, [
    (vbo1, '3f 3f', 'in_vert', 'in_norm'),  # no list needed
    #         ^ space is obligatory
    ...
])

Buffer Format Half-Floats¶

ModernGL4

Not available in ModernGL4

ModernGL5

my_vertex_array = ctx.vertex_array(prog, [
    (vbo1, '3f2 3f2', 'in_vert', 'in_norm'),  # '3f2' means '3' of 'f2', where 'f2' is a half-float
    ...
])

Buffer Format Padding¶

ModernGL4

my_vertex_array = ctx.vertex_array(prog, [
    (vbo1, '3f12x', ['in_vert']),  # same as above, in_norm was replaced with padding
    ...
])

ModernGL5

my_vertex_array = ctx.vertex_array(prog, [
    (vbo1, '3f 3x4', ['in_vert']),  # '3x4' means '3' of 'x4', where 'x4' means 4 bytes of padding
    ...
])

Buffer Format Errors¶

Let’s assume in_vert was declared as: in vec4 in_vert

ModernGL4

my_vertex_array = ctx.vertex_array(prog, [
    (vbo1, '3f', ['in_vert']),  # throws an error (3 != 4)
    ...
])

my_vertex_array = ctx.vertex_array(prog, [
    (vbo1, '4i', ['in_vert']),  # throws an error (float != int)
    ...
])

ModernGL5

my_vertex_array = ctx.vertex_array(prog, [
    (vbo1, '3f', 'in_vert'),  # totally fine
    ...
])

my_vertex_array = ctx.vertex_array(prog, [
    (vbo1, '4i', 'in_vert'),  # totally fine
    ...
])

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