glitter: A Python repository from adamlwgriffiths

glitter is an intuitive wrapper around OpenGL 3 and up.

Code example

The following code creates a window displaying a rotating quad:

from math import cos, sin
from glitter import VertexArray, get_default_program
from glitter.contexts.glut import GlutWindow, main_loop, get_elapsed_time

vertices = ((0, 0, 0), (-1, 1, 0), (1, 1, 0), (1, -1, 0), (-1, -1, 0))
colors = ((1, 1, 1), (0, 1, 0), (0, 0, 1), (0, 1, 1), (1, 0, 0))
indices = ((0, 1, 2), (0, 2, 3), (0, 3, 4), (0, 4, 1))

def display():
    window.clear()
    vao.draw()
    window.swap_buffers()

def timer():
    phi = get_elapsed_time()
    shader.modelview_matrix = (
                    ( cos(phi), sin(phi), 0, 0),
                    (-sin(phi), cos(phi), 0, 0),
                    (        0,        0, 1, 0),
                    (        0,        0, 0, 2)
            )
    window.add_timer(10, timer)
    window.post_redisplay()

if __name__ == "__main__":
    window = GlutWindow(double=True, multisample=True)
    window.display_callback = display
    shader = get_default_program()
    vao = VertexArray([vertices, colors], elements=indices)
    timer()
    with shader:
        main_loop()

Design principles

Glitter wraps the OpenGL 3 core profile only. This allows for a pythonic representation of (eventually) the complete OpenGL API, while any nuts and bolts are readily supplied by Python and numpy.
Inituitive use is chosen over performance (no premature optimization; make it run, then make it fast). Users do not need to (nor should they) use raw GL functions at any time.
OpenGL objects (e.g., textures, buffers, or shader programs) are represented by Python objects.
All GL state changes go through either a context object or a responsible object, for example:
- Vertex attribute pointer bindings are performed by vertex array objects.
- Settings for draw buffers other than the screen are performed by framebuffer objects.
- Texture bindings are performed by shader programs. An available texture unit is chosen automatically.
Array data (e.g. texture images or vertex buffer data) is represented in numpy.
Glitter has a focus on GPGPU computing, but typical use for rendering should be as easy.
Platform independence is be sought for, although Linux/GLX is currently the primary target. Any experiences with other platforms are very welcome.

Dependencies

gccxml: http://www.gccxml.org
ctypeslib: http://pypi.python.org/pypi/ctypeslib

Build instructions

installing: sudo python setup.py install
docs: cd docs; ./build.sh
tests: nosetests tests
installing with Python 3: run python setup.py build with Python 2, then 2to3 -w build and manually install the files from the build folder

OpenGL 3 notes

The distribution includes the official OpenGL 3 header file from http://www.opengl.org/registry/api/gl3.h, with the following bugfixes applied:

The following functions are not part of the core profile and have been removed:

GLAPI void APIENTRY glVertexP2ui (GLenum type, GLuint value);
GLAPI void APIENTRY glVertexP2uiv (GLenum type, const GLuint *value);
GLAPI void APIENTRY glVertexP3ui (GLenum type, GLuint value);
GLAPI void APIENTRY glVertexP3uiv (GLenum type, const GLuint *value);
GLAPI void APIENTRY glVertexP4ui (GLenum type, GLuint value);
GLAPI void APIENTRY glVertexP4uiv (GLenum type, const GLuint *value);
GLAPI void APIENTRY glTexCoordP1ui (GLenum type, GLuint coords);
GLAPI void APIENTRY glTexCoordP1uiv (GLenum type, const GLuint *coords);
GLAPI void APIENTRY glTexCoordP2ui (GLenum type, GLuint coords);
GLAPI void APIENTRY glTexCoordP2uiv (GLenum type, const GLuint *coords);
GLAPI void APIENTRY glTexCoordP3ui (GLenum type, GLuint coords);
GLAPI void APIENTRY glTexCoordP3uiv (GLenum type, const GLuint *coords);
GLAPI void APIENTRY glTexCoordP4ui (GLenum type, GLuint coords);
GLAPI void APIENTRY glTexCoordP4uiv (GLenum type, const GLuint *coords);
GLAPI void APIENTRY glMultiTexCoordP1ui (GLenum texture, GLenum type, GLuint coords);
GLAPI void APIENTRY glMultiTexCoordP1uiv (GLenum texture, GLenum type, const GLuint *coords);
GLAPI void APIENTRY glMultiTexCoordP2ui (GLenum texture, GLenum type, GLuint coords);
GLAPI void APIENTRY glMultiTexCoordP2uiv (GLenum texture, GLenum type, const GLuint *coords);
GLAPI void APIENTRY glMultiTexCoordP3ui (GLenum texture, GLenum type, GLuint coords);
GLAPI void APIENTRY glMultiTexCoordP3uiv (GLenum texture, GLenum type, const GLuint *coords);
GLAPI void APIENTRY glMultiTexCoordP4ui (GLenum texture, GLenum type, GLuint coords);
GLAPI void APIENTRY glMultiTexCoordP4uiv (GLenum texture, GLenum type, const GLuint *coords);
GLAPI void APIENTRY glNormalP3ui (GLenum type, GLuint coords);
GLAPI void APIENTRY glNormalP3uiv (GLenum type, const GLuint *coords);
GLAPI void APIENTRY glColorP3ui (GLenum type, GLuint color);
GLAPI void APIENTRY glColorP3uiv (GLenum type, const GLuint *color);
GLAPI void APIENTRY glColorP4ui (GLenum type, GLuint color);
GLAPI void APIENTRY glColorP4uiv (GLenum type, const GLuint *color);
GLAPI void APIENTRY glSecondaryColorP3ui (GLenum type, GLuint color);
GLAPI void APIENTRY glSecondaryColorP3uiv (GLenum type, const GLuint *color);

The following constants are missing and have been defined:

#define GL_POLYGON_MODE                   0x0B40

Changelog

The following versions introduced noteworthy features, bug fixes, or API changes:

version 0.1.7

Fix install_requires in setup script.
Fix GLUT modifier key functions.
Add rudimentary support for glReadPixels on Context objects.
Fix glActiveTexture call when calling bind() on already bound Texture.

version 0.1.6

Add support for depth and stencil textures.
Additional examples.
Python 3 compatibility (built distribution only, not build script).
Add GLX and dummy contexts (GLX context via separate glxcontext package), GLX is now the default if available.
Fix Framebuffer viewport.
Rename and add parameters to copy pipeline.
Add convenience matrix functions.
Fix setattr bug in Pipeline.

version 0.1.5

Add support for integer sampler types in glitter.convenience.

version 0.1.4

Framebuffers expect attributes as separate __init__() parameters instead of a list.
Implement mesh loading from HDF5.
Fix context bugs in VertexArray, Pipeline, and ShaderProgram.
Fix shader proxies in Pipeline.
Pipeline now uses the currently bound framebuffer instead of the default framebuffer.
Add context properties to Pipeline.

version 0.1.3

Introduce literate example programs.
ArrayBuffers determine the primitive type and check the buffer dimensions separately.
GLObjects accept a context parameter to __init__().
VertexArrays expect attributes as separate __init__() parameters instead of a list.
Fix bug in ContextManger (did not call _bind()) and add caching.
Cast parameters that should be EnumConstants into the appropriate types and accept constant names in addition to constant objects.
Add Qt support via PySide or PyQt4.
Add plausibility checks to avoid huge memory allocation when a Context object was created without a valid OpenGL context.
Make color and modelview matrix optional in defaultpipeline.

adamlwgriffiths/glitter