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Intuitive OpenGL wrappers

Project description

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.

Build instructions

  • installing: sudo python setup.py install
  • docs: cd docs; ./build.sh
  • tests: nosetests tests

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 0.1.4

  • 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.

Project details


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