Re: [PyOpenGL-Users] Checking Shader Errors

[Gijs <in...@bs...>]

Ian Mallett wrote:
> Hi,
>
> I've got a great shader library, and it's nearly done.  Unfortunately,
> certain custom functions have problems on ATI cards.  I'm trying to
> add error reporting to get useful errors about it.  Unfortunately,
> glGetShaderInfoLog() seems to fail.  It works for me, with NVidia. 
>
> This function:
>
> def CompileShader(source,shaderType):
>     shader = glCreateShaderObjectARB(shaderType)
>     glShaderSourceARB(shader,[source])
>     glCompileShaderARB(shader)
>     return shader
>
> provides the "shader" that is passed as the argument to
> glGetShaderInfoLog().  I have no idea what's wrong, and I really need
> to have error reporting to debug this. 
>
> Curiously, glGetInfoLogARB() seems to work fine, but it does not give
> useful errors (fragment shader failed to compile successfully before
> linking or some such).  I tried using ctypes in ways like here
> <http://www.pygame.org/wiki/GLSLExample?parent=CookBook> or here
> <http://www.pygame.org/wiki/GLSL_ARB_Example?parent=CookBook>, but
> they don't work for either of us.
>
> I need errors.  Help.
>
> Thanks,
> Ian

Hey Ian,

I made some error reporting code for my own stuff a while back. Maybe
you can use some of it to see what is going wrong with your code.

Regards,
Gijs


def compileShader(source, shader_type, shader_name):
  shader = glCreateShaderObjectARB(shader_type)
  glShaderSourceARB(shader, source)
  glCompileShaderARB(shader)

  status = glGetObjectParameterivARB(shader, GL_COMPILE_STATUS)
  if not status:
    printShaderLog(shader, shader_name)
    glDeleteObjectARB(shader)
    raise ValueError, 'Shader compilation failed'

  return shader


def compileProgram(vertex_source, fragment_source, shader_name):
  vertex_shader   = None
  fragment_shader = None
  program         = glCreateProgramObjectARB()

  if (type(vertex_source) == str):
    vertex_source = [vertex_source]
  if (type(fragment_source) == str):
    fragment_source = [fragment_source]

  if vertex_source:
    vertex_shader = compileShader(vertex_source, GL_VERTEX_SHADER,
shader_name)
    glAttachObjectARB(program, vertex_shader)
  if fragment_source:
    fragment_shader = compileShader(fragment_source, GL_FRAGMENT_SHADER,
shader_name)
    glAttachObjectARB(program, fragment_shader)

  glLinkProgramARB(program)
  status = glGetObjectParameterivARB(program, GL_OBJECT_LINK_STATUS_ARB)
  if not status:
    print >> sys.stderr, glGetInfoLogARB(program)
    raise ValueError, 'Failed to link shader ('+str(shader_name)+')'

  glValidateProgramARB(program)
  status = glGetObjectParameterivARB(program, GL_OBJECT_VALIDATE_STATUS_ARB)
  if not status:
    print >> sys.stderr, glGetInfoLogARB(program)
    raise ValueError, 'Failed to validate shader ('+str(shader_name)+')'

  if vertex_shader:
    glDeleteObjectARB(vertex_shader)
  if fragment_shader:
    glDeleteObjectARB(fragment_shader)

  if glGetObjectParameterivARB(program, GL_INFO_LOG_LENGTH) > 0:
    print ("Info log for shader '" + str(shader_name) + "':\n" +
glGetInfoLogARB(program))

  return program


def printShaderLog(shader, shader_name):
  if glGetObjectParameterivARB(shader, GL_INFO_LOG_LENGTH) > 0:
    log = glGetInfoLogARB(shader)
    print >> sys.stderr, "Problem with shader '" + shader_name + "'"
    print >> sys.stderr, log
  else:
    print >> sys.stderr, "Problem with shader '" + shader_name + "', but
no log is available"