>Psychtoolbox>PsychOpenGL

handle = LoadGLSLProgramFromFiles(filenames [, debug=0] [, extraShaders])
Loads a GLSL OpenGL shading language program. All shader definition files in
‘filenames’ are read, shaders are built for each definition and all
shaders are linked together into a new GLSL program. Returns a handle to
the new program, if successfull. The optional ‘debug’ flag allows to enable
debugging output: Zero = no output, 1 = a bit of output, 2 = detailed
output, 3 = Don’t compile and link anymore, but print out the shaders
source code as OpenGL would see it.

The program can then be used at any time by calling glUseProgram(handle). One
can switch back to the standard OpenGL fixed-function pipeline by calling
glUseProgram(0). The same handles can be passed to the
Screen(‘MakeTexture’, …), Screen(‘DrawTexture’, …); et al. routines
to define procedural textures - or some processing operations on them
via the ‘textureShader’ argument – See ‘help ProceduralShadingAPI’ for
more info about procedural texturing. The handle is also used to build
GLOperators for Screen(‘TransformTexture’) or as plugins for the imaging
pipeline: See ‘help CreateGLOperator’ or ‘help AddToGLOperator’ for info.

‘filenames’ can have one of two formats: If filenames is a array of
strings that define the names of the shaders to use, then all shader
files are loaded, compiled and linked into a single program. E.g.,
shaderfiles={ ‘myshader.vert’ , ‘myothershader.frag’}; will try to load
the two shaderfiles myshader.vert and myothershader.frag and link them
into a valid program.

If only a single filename is given, then all shaders beginning with that
name are linked into a program. E.g., shaderfiles = ‘Phonglighting’ will
try to link all files starting with Phonglighting.

The optional argument ‘extraShaders’ if present, should be a vector of
additinal shader handles - Handles returned by the LoadShaderFromFile()
or by your self-compiled shaders via glCompileShader(). All precompiled
shaders referenced by those handles get also linked into the final GLSL
program.