glBlendColorEXT - set the blend color
void glBlendColorEXT( GLclampf red,
GLclampf green,
GLclampf blue,
GLclampf alpha )
red, green, blue, alpha specify the components of
The GL_BLEND_COLOR_EXT may be used to calculate the source and destination blending factors. See glBlendFunc for a complete description of the blending operations. Initially the GL_BLEND_COLOR_EXT is set to (0,0,0,0).
glBlendColorEXT is part of the EXT_blend_color extension, not part of the core GL command set. If GL_EXT_blend_color is included in the string returned by glGetString, when called with argument GL_EXTENSIONS, extension EXT_blend_color is supported by the connection.
GL_INVALID_OPERATION is generated if glBlendColorEXT is executed between the execution of glBegin and the corresponding execution of glEnd.
glGet with an argument of GL_BLEND_COLOR_EXT.