Using GLSL with PyOpenGL

  1from ctypes import *
  2import sys
  3 
  4import pygame
  5from pygame.locals import *
  6 
  7try:
  8    # For OpenGL-ctypes
  9    from OpenGL import platform
 10    gl = platform.OpenGL
 11except ImportError:
 12    try:
 13        # For PyOpenGL
 14        gl = cdll.LoadLibrary('libGL.so')
 15    except OSError:
 16        # Load for Mac
 17        from ctypes.util import find_library
 18        # finds the absolute path to the framework
 19        path = find_library('OpenGL')
 20        gl = cdll.LoadLibrary(path)
 21 
 22from OpenGL.GL import *
 23from OpenGL.GLU import *
 24 
 25glCreateShader = gl.glCreateShader
 26glShaderSource = gl.glShaderSource
 27glShaderSource.argtypes = [c_int, c_int, POINTER(c_char_p), POINTER(c_int)]
 28glCompileShader = gl.glCompileShader
 29glGetShaderiv = gl.glGetShaderiv
 30glGetShaderiv.argtypes = [c_int, c_int, POINTER(c_int)]
 31glGetShaderInfoLog = gl.glGetShaderInfoLog
 32glGetShaderInfoLog.argtypes = [c_int, c_int, POINTER(c_int), c_char_p]
 33glGetUniformLocation = gl.glGetUniformLocation
 34glUniform1i = gl.glUniform1i
 35glDeleteShader = gl.glDeleteShader
 36glCreateProgram = gl.glCreateProgram
 37glAttachShader = gl.glAttachShader
 38glLinkProgram = gl.glLinkProgram
 39glGetError = gl.glGetError
 40glUseProgram = gl.glUseProgram
 41 
 42GL_FRAGMENT_SHADER = 0x8B30
 43GL_VERTEX_SHADER = 0x8B31
 44GL_COMPILE_STATUS = 0x8B81
 45GL_LINK_STATUS = 0x8B82
 46GL_INFO_LOG_LENGTH = 0x8B84
 47 
 48def compile_shader(source, shader_type):
 49    shader = glCreateShader(shader_type)
 50    source = c_char_p(source)
 51    length = c_int(-1)
 52    glShaderSource(shader, 1, byref(source), byref(length))
 53    glCompileShader(shader)
 54    
 55    status = c_int()
 56    glGetShaderiv(shader, GL_COMPILE_STATUS, byref(status))
 57    if not status.value:
 58        print_log(shader)
 59        glDeleteShader(shader)
 60        raise ValueError, 'Shader compilation failed'
 61    return shader
 62 
 63def compile_program(vertex_src, fragment_src):
 64    '''
 65    Compile a Shader program given the vertex
 66    and fragment sources
 67    '''
 68    
 69    shaders = []
 70    
 71    program = glCreateProgram()
 72
 73    for shader_type, src in ((GL_VERTEX_SHADER, vertex_src),
 74                             (GL_FRAGMENT_SHADER, fragment_src)):
 75        shader = compile_shader(src, shader_type)
 76        glAttachShader(program, shader)
 77        shaders.append(shader)
 78
 79    glLinkProgram(program)
 80 
 81    for shader in shaders:
 82        glDeleteShader(shader)
 83 
 84    return program
 85 
 86def print_log(shader):
 87    length = c_int()
 88    glGetShaderiv(shader, GL_INFO_LOG_LENGTH, byref(length))
 89 
 90    if length.value > 0:
 91        log = create_string_buffer(length.value)
 92        glGetShaderInfoLog(shader, length, byref(length), log)
 93        print >> sys.stderr, log.value
 94
 95if __name__ == '__main__':
 96
 97    from OpenGL.GLUT import glutInit, glutSolidTeapot
 98    glutInit(sys.argv)
 99    width, height = 640, 480
100    pygame.init()
101    pygame.display.set_mode((width, height), OPENGL | DOUBLEBUF)
102 
103    program = compile_program('''
104    // Vertex program
105    varying vec3 pos;
106    void main() {
107        pos = gl_Vertex.xyz;
108        gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
109    }
110    ''', '''
111    // Fragment program
112    varying vec3 pos;
113    void main() {
114        gl_FragColor.rgb = pos.xyz;
115    }
116    ''')
117 
118    glMatrixMode(GL_PROJECTION)
119    glLoadIdentity()
120    gluPerspective(90.0, width / float(height), 1.0, 100.0)
121    glMatrixMode(GL_MODELVIEW)
122    glEnable(GL_DEPTH_TEST)
123    
124    quit = False
125    angle = 0
126    while not quit:
127        for e in pygame.event.get():
128            if e.type in (QUIT, KEYDOWN):
129                quit = True
130        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
131        glLoadIdentity()
132        glTranslate(0.0, 0.0, - 2.5)
133        glRotate(angle, 0.0, 1.0, 0.0)
134        glUseProgram(program)
135        glutSolidTeapot(1.0)
136        angle += 0.1 
137        pygame.display.flip()