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"""Convenience module providing common shader entry points
The point of this module is to allow client code to use
OpenGL 2.x style names to reference shader-related operations
even if the local hardware only supports ARB extension-based
shader rendering.
There are also two utility methods compileProgram and compileShader
which make it easy to create demos which are shader-using.
"""
import logging
logging.basicConfig()
log = logging.getLogger( 'OpenGL.GL.shaders' )
from OpenGL import GL
from OpenGL.GL.ARB import shader_objects, fragment_shader, vertex_shader, vertex_program
from OpenGL.extensions import alternate
__all__ = [
'glAttachShader',
'glDeleteShader',
'glGetProgramInfoLog',
'glGetShaderInfoLog',
'glGetProgramiv',
'glGetShaderiv',
'compileProgram',
'compileShader',
'GL_VALIDATE_STATUS',
'GL_LINK_STATUS',
# automatically added stuff here...
]
def _alt( base, name ):
if hasattr( GL, base ):
root = getattr( GL, base )
if hasattr(root,'__call__'):
globals()[base] = alternate(
getattr(GL,base),
getattr(module,name)
)
__all__.append( base )
else:
globals()[base] = root
__all__.append( base )
return True
return False
_excludes = ['glGetProgramiv']
for module in shader_objects,fragment_shader,vertex_shader,vertex_program:
for name in dir(module):
found = None
for suffix in ('ObjectARB','_ARB','ARB'):
if name.endswith( suffix ):
found = False
base = name[:-(len(suffix))]
if base not in _excludes:
if _alt( base, name ):
found = True
break
if found is False:
log.debug( '''Found no alternate for: %s.%s''',
module.__name__,name,
)
glAttachShader = alternate( GL.glAttachShader,shader_objects.glAttachObjectARB )
glDetachShader = alternate( GL.glDetachShader,shader_objects.glDetachObjectARB )
glDeleteShader = alternate( GL.glDeleteShader,shader_objects.glDeleteObjectARB )
glGetAttachedShaders = alternate( GL.glGetAttachedShaders, shader_objects.glGetAttachedObjectsARB )
glGetProgramInfoLog = alternate( GL.glGetProgramInfoLog, shader_objects.glGetInfoLogARB )
glGetShaderInfoLog = alternate( GL.glGetShaderInfoLog, shader_objects.glGetInfoLogARB )
glGetShaderiv = alternate( GL.glGetShaderiv, shader_objects.glGetObjectParameterivARB )
glGetProgramiv = alternate( GL.glGetProgramiv, shader_objects.glGetObjectParameterivARB )
GL_VALIDATE_STATUS = GL.GL_VALIDATE_STATUS
GL_COMPILE_STATUS = GL.GL_COMPILE_STATUS
GL_LINK_STATUS = GL.GL_LINK_STATUS
GL_FALSE = GL.GL_FALSE
class ShaderProgram( int ):
"""Integer sub-class with context-manager operation"""
def __enter__( self ):
"""Start use of the program"""
glUseProgram( self )
def __exit__( self, typ, val, tb ):
"""Stop use of the program"""
glUseProgram( 0 )
def compileProgram(*shaders):
"""Create a new program, attach shaders and validate
shaders -- arbitrary number of shaders to attach to the
generated program.
This convenience function is *not* standard OpenGL,
but it does wind up being fairly useful for demos
and the like. You may wish to copy it to your code
base to guard against PyOpenGL changes.
Usage:
shader = compileProgram(
compileShader( source, GL_VERTEX_SHADER ),
compileShader( source2, GL_FRAGMENT_SHADER ),
)
glUseProgram( shader )
Note:
If (and only if) validation of the linked program
*passes* then the passed-in shader objects will be
deleted from the GL.
returns GLuint shader program reference
raises RuntimeError when a link/validation failure occurs
"""
program = glCreateProgram()
for shader in shaders:
glAttachShader(program, shader)
glLinkProgram(program)
# Validation has to occur *after* linking
glValidateProgram( program )
validation = glGetProgramiv( program, GL_VALIDATE_STATUS )
if validation == GL_FALSE:
raise RuntimeError(
"""Validation failure (%s): %s"""%(
validation,
glGetProgramInfoLog( program ),
))
link_status = glGetProgramiv( program, GL_LINK_STATUS )
if link_status == GL_FALSE:
raise RuntimeError(
"""Link failure (%s): %s"""%(
link_status,
glGetProgramInfoLog( program ),
))
for shader in shaders:
glDeleteShader(shader)
return ShaderProgram( program )
def compileShader( source, shaderType ):
"""Compile shader source of given type
source -- GLSL source-code for the shader
shaderType -- GLenum GL_VERTEX_SHADER, GL_FRAGMENT_SHADER, etc,
returns GLuint compiled shader reference
raises RuntimeError when a compilation failure occurs
"""
if isinstance( source, (str,unicode)):
source = [ source ]
shader = glCreateShader(shaderType)
glShaderSource( shader, source )
glCompileShader( shader )
result = glGetShaderiv( shader, GL_COMPILE_STATUS )
if not(result):
# TODO: this will be wrong if the user has
# disabled traditional unpacking array support.
raise RuntimeError(
"""Shader compile failure (%s): %s"""%(
result,
glGetShaderInfoLog( shader ),
),
source,
shaderType,
)
return shader
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