Jakub Marian wrote 12 lines
Hello, I've been trying to solve the problem with the unit GLext for some
time and I am getting mad. I need to use vertex shaders written in GLSL, but
I am a novice in that field so I may be doing domething wrong. I have glext
in my "uses". I tried just to call glCreateProgramObjectARB but I've got
access violation in my program. So I looked into source of glext and there
are some functions which look like I could use them. So I tried
glext_LoadExtension('GL_version_1_4'). Same problem - access violation. So I
tried glext_ExtensionSupported with some parameters. Access violation. I am
really getting mad, I have no idea what to do.
I am really opened to any suggestions :-)
glCreateProgramObjectARB is part of GL_ARB_shader_objects extension (see OpenGL extension registry on opengl.org). So what you want to call is Load_GL_ARB_shader_objects
or (equivalent)
glext_LoadExtension('GL_ARB_shader_objects')
They both return boolean value, if true --- then your OpenGL supports this extension, and glCreateProgramObjectARB entry point is initialized to non-nil and you can call it without any access violations.
glext_LoadExtension('GL_version_1_4') loads OpenGL features that are standard in OpenGL 1.4, this has nothing to do with glCreateProgramObjectARB ("ARB" suffix says this is an extension).
OpenGL 2.0 introduced shaders as standard, so you may want to call Load_GL_version_2_0 and then use glCreateProgram instead of glCreateProgramObjectARB. But for now, using extension is a little safer (more chance that given OpenGL implementation will support it).
Oh, and if you have downloaded my engine mentioned in previous mail --- see kambi_vrml_game_engine/opengl/glshaders.pas, this is my unit for handling OpenGL shaders, see TGLSLProgram class.
Michalis
