osx man page for glblendcolor

GLBLENDCOLOR(3G)														  GLBLENDCOLOR(3G)

NAME
       glBlendColor - set the blend color

C SPECIFICATION
       void glBlendColor( GLclampf red,
			  GLclampf green,
			  GLclampf blue,
			  GLclampf alpha )

PARAMETERS
       red, green, blue, alpha
			     specify the components of GL_BLEND_COLOR

DESCRIPTION
       The  GL_BLEND_COLOR  may  be  used  to calculate the source and destination blending factors. The color components are clamped to the range
       [0, 1] before being stored. See glBlendFunc for a complete description of the blending operations.  Initially the GL_BLEND_COLOR is set	to
       (0, 0, 0, 0).

NOTES
       glBlendColor  is  part  of the GL_ARB_imaging subset. glBlendColor is present only if GL_ARB_imaging is returned when glGetString is called
       with GL_EXTENSIONS as its argument.

ERRORS
       GL_INVALID_OPERATION is generated if glBlendColor is executed between the execution of glBegin and the corresponding execution of glEnd.

ASSOCIATED GETS
       glGet with an argument of GL_BLEND_COLOR

SEE ALSO
       glBlendEquation, glBlendFunc, glGetString

																  GLBLENDCOLOR(3G)