Two Methods of Multitexture In Cg

Method 1: Using OpenGL's native multi-texture support (using semantics)

// In C++ File:

// Identify the textures to use for the pixel shader...
cgGLSetTextureParameter( g_CGparam_testTexture, g_testTextureID );
cgGLSetTextureParameter( g_CGparam_checkerTexture, g_checkerTextureID );

// STAGE 0
glActiveTextureARB( GL_TEXTURE0_ARB );
glBindTexture( GL_TEXTURE_2D, g_testTextureID );

// STAGE 1
glActiveTextureARB( GL_TEXTURE1_ARB );
glBindTexture( GL_TEXTURE_2D, g_checkerTextureID );

cgGLBindProgram( g_CGprogram_pixel );
cgGLEnableProfile( g_CGprofile_pixel );

// Draw primitives

cgGLDisableProfile( g_CGprofile_pixel );

// In Cg File:

uniform sampler2D testTexture : TEXUNIT0,
uniform sampler2D checkerTexture : TEXUNIT1

Method 2: Using Cg's special texture functions:cgGLSetTextureParameter, cgGLEnableTextureParameter, and cgGLDisableTextureParameter

// In C++ File:

g_CGparam_testTexture = cgGetNamedParameter(g_CGprogram_pixel, "testTexture");
g_CGparam_checkerTexture = cgGetNamedParameter(g_CGprogram_pixel, "checkerTexture");

// Identify the textures to use for the pixel shader...
cgGLSetTextureParameter( g_CGparam_testTexture, g_testTextureID );
cgGLSetTextureParameter( g_CGparam_checkerTexture, g_checkerTextureID );

cgGLBindProgram( g_CGprogram_pixel );
cgGLEnableProfile( g_CGprofile_pixel );

cgGLEnableTextureParameter( g_CGparam_testTexture );
cgGLEnableTextureParameter( g_CGparam_checkerTexture );

// Draw primitives

cgGLDisableTextureParameter( g_CGparam_checkerTexture );
cgGLDisableTextureParameter( g_CGparam_testTexture );

cgGLDisableProfile( g_CGprofile_pixel );

// In Cg File:

uniform sampler2D testTexture,

uniform sampler2D checkerTexture