Using GLSL programs in python pyopengl

Here is an easy straightforward example of using GLSL shader programs with pyopengl.

To use this you will need to import the following:

from OpenGL.GL import *
from OpenGL.GLU import *

Thus we will need pyopengl package installed.

 ##compile and link shader
 vs = fs = 0
 
 vs = glCreateShader(GL_VERTEX_SHADER)
 fs = glCreateShader(GL_FRAGMENT_SHADER)
 
 vs_source = """
  void main(void) {
     gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
  }
 """
 fs_source = """
  void main (void)  {     
     gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);  
  } 
 """
 glShaderSource(vs, vs_source)
 glShaderSource(fs, fs_source)
 
 glCompileShader(vs)
 log = glGetShaderInfoLog(vs)
 if log: print 'Vertex Shader: ', log
 
 glCompileShader(fs)
 log = glGetShaderInfoLog(fs)
 if log: print 'Fragment Shader: ', log
 
 prog = glCreateProgram()
 glAttachShader(prog, vs)
 glAttachShader(prog, fs)

 glLinkProgram(prog)
 glUseProgram(prog)

glShaderSource(shader_id, text) is a handy python function that will load our shader for us into opengl.


I also have a handy shader class I use in my engine program. Here it is:

class shader(node) :
 def __init__(self, filename):
  node.__init__(self)
  fh = open(filename)  
  self.source = {'vertex': '', 'fragment':''}
  write = None
  for line in fh :
   if line == '[[vertex-program]]\n' : 
    write = 'vertex'
   elif line == '[[fragment-program]]\n' : 
    write = 'fragment'
   else :
    self.source[write] += line
    
  self.draw = self.init
    
 def init(self):
  ##compile and link shader
  self.vs = self.fs = 0

  self.vs = glCreateShader(GL_VERTEX_SHADER)
  self.fs = glCreateShader(GL_FRAGMENT_SHADER)

  glShaderSource(self.vs, self.source['vertex'])
  glShaderSource(self.fs, self.source['fragment'])

  glCompileShader(self.vs)
  log = glGetShaderInfoLog(self.vs)
  if log: print 'Vertex Shader: ', log

  glCompileShader(self.fs)
  log = glGetShaderInfoLog(self.fs)
  if log: print 'Fragment Shader: ', log

  self.prog = glCreateProgram()
  glAttachShader(self.prog, self.vs)
  glAttachShader(self.prog, self.fs)

  glLinkProgram(self.prog)
  self.use()
  self.draw = self.use

 def use(self):
  glUseProgram(self.prog)
  
 def end(self):
  glUseProgram(0)