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GLBLENDFUNCSEPARATE(3G) 		  OpenGL Manual 		  GLBLENDFUNCSEPARATE(3G)

NAME
       glBlendFuncSeparate - specify pixel arithmetic for RGB and alpha components separately

C SPECIFICATION
       void glBlendFuncSeparate(GLenum srcRGB, GLenum dstRGB, GLenum srcAlpha, GLenum dstAlpha);

       void glBlendFuncSeparatei(GLuint buf, GLenum srcRGB, GLenum dstRGB, GLenum srcAlpha,
				 GLenum dstAlpha);

PARAMETERS
       buf
	   For glBlendFuncSeparatei, specifies the index of the draw buffer for which to set the
	   blend functions.

       srcRGB
	   Specifies how the red, green, and blue blending factors are computed. The initial
	   value is GL_ONE.

       dstRGB
	   Specifies how the red, green, and blue destination blending factors are computed. The
	   initial value is GL_ZERO.

       srcAlpha
	   Specified how the alpha source blending factor is computed. The initial value is
	   GL_ONE.

       dstAlpha
	   Specified how the alpha destination blending factor is computed. The initial value is
	   GL_ZERO.

DESCRIPTION
       Pixels can be drawn using a function that blends the incoming (source) RGBA values with
       the RGBA values that are already in the frame buffer (the destination values). Blending is
       initially disabled. Use glEnable() and glDisable() with argument GL_BLEND to enable and
       disable blending.

       glBlendFuncSeparate defines the operation of blending for all draw buffers when it is
       enabled.  glBlendFuncSeparatei defines the operation of blending for a single draw buffer
       specified by buf when enabled for that draw buffer.  srcRGB specifies which method is used
       to scale the source RGB-color components.  dstRGB specifies which method is used to scale
       the destination RGB-color components. Likewise, srcAlpha specifies which method is used to
       scale the source alpha color component, and dstAlpha specifies which method is used to
       scale the destination alpha component. The possible methods are described in the following
       table. Each method defines four scale factors, one each for red, green, blue, and alpha.

       In the table and in subsequent equations, first source, second source and destination
       color components are referred to as R s0 G s0 B s0 A s0, R s1 G s1 B s1 A s1, and R d G d
       B d A d, respectively. The color specified by glBlendColor() is referred to as R c G c B c
       A c. They are understood to have integer values between 0 and k R k G k B k A, where

       and m R m G m B m A is the number of red, green, blue, and alpha bitplanes.

       Source and destination scale factors are referred to as s R s G s B s A and d R d G d B d
       A. All scale factors have range 0 1.

       +----------------------------------+--------------------------------------------+----------------------------------------+
       |				  |					       |					|
       |			Parameter |			    RGB 	       |			 Alpha		|
       |				  | Factor				       | Factor 				|
       |				  |					       |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_ZERO 			  | 0					       | 0					|
       |				  |				    0	       |					|
       |				  |				    0	       |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_ONE				  | 1					       | 1					|
       |				  |				    1	       |					|
       |				  |				    1	       |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_SRC_COLOR			  | R					       | A					|
       |				  |					s0     |				 s0	|
       |				  |					       |					|
       |				  |					k      |				 k	|
       |				  |					R      |				 A	|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					G      |					|
       |				  |					s0     |					|
       |				  |					       |					|
       |				  |					k      |					|
       |				  |					G      |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					B      |					|
       |				  |					s0     |					|
       |				  |					       |					|
       |				  |					k      |					|
       |				  |					B      |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_ONE_MINUS_SRC_COLOR		  | 1					       | 1					|
       |				  |					1      |				 -	|
       |				  |					1      |					|
       |				  |					1      |				     A	|
       |				  |					       |				     s0 |
       |				  |				    -	       |					|
       |				  |					       |				     k	|
       |				  |					       |				     A	|
       |				  |					    R  |					|
       |				  |					    s0 |					|
       |				  |					       |					|
       |				  |					    k  |					|
       |				  |					    R  |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					    G  |					|
       |				  |					    s0 |					|
       |				  |					       |					|
       |				  |					    k  |					|
       |				  |					    G  |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					    B  |					|
       |				  |					    s0 |					|
       |				  |					       |					|
       |				  |					    k  |					|
       |				  |					    B  |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_DST_COLOR			  | R					       | A					|
       |				  |					d      |				 d	|
       |				  |					       |					|
       |				  |					k      |				 k	|
       |				  |					R      |				 A	|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					G      |					|
       |				  |					d      |					|
       |				  |					       |					|
       |				  |					k      |					|
       |				  |					G      |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					B      |					|
       |				  |					d      |					|
       |				  |					       |					|
       |				  |					k      |					|
       |				  |					B      |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_ONE_MINUS_DST_COLOR		  | 1					       | 1					|
       |				  |					1      |				 -	|
       |				  |					1      |					|
       |				  |					       |				     A	|
       |				  |				    -	       |				     d	|
       |				  |					       |					|
       |				  |					       |				     k	|
       |				  |					    R  |				     A	|
       |				  |					    d  |					|
       |				  |					       |					|
       |				  |					    k  |					|
       |				  |					    R  |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					    G  |					|
       |				  |					    d  |					|
       |				  |					       |					|
       |				  |					    k  |					|
       |				  |					    G  |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					    B  |					|
       |				  |					    d  |					|
       |				  |					       |					|
       |				  |					    k  |					|
       |				  |					    B  |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_SRC_ALPHA			  | A					       | A					|
       |				  |					s0     |				 s0	|
       |				  |					       |					|
       |				  |					k      |				 k	|
       |				  |					A      |				 A	|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					A      |					|
       |				  |					s0     |					|
       |				  |					       |					|
       |				  |					k      |					|
       |				  |					A      |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					A      |					|
       |				  |					s0     |					|
       |				  |					       |					|
       |				  |					k      |					|
       |				  |					A      |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_ONE_MINUS_SRC_ALPHA		  | 1					       | 1					|
       |				  |					1      |				 -	|
       |				  |					1      |					|
       |				  |					       |				     A	|
       |				  |				    -	       |				     s0 |
       |				  |					       |					|
       |				  |					       |				     k	|
       |				  |					    A  |				     A	|
       |				  |					    s0 |					|
       |				  |					       |					|
       |				  |					    k  |					|
       |				  |					    A  |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					    A  |					|
       |				  |					    s0 |					|
       |				  |					       |					|
       |				  |					    k  |					|
       |				  |					    A  |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					    A  |					|
       |				  |					    s0 |					|
       |				  |					       |					|
       |				  |					    k  |					|
       |				  |					    A  |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_DST_ALPHA			  | A					       | A					|
       |				  |					d      |				 d	|
       |				  |					       |					|
       |				  |					k      |				 k	|
       |				  |					A      |				 A	|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					A      |					|
       |				  |					d      |					|
       |				  |					       |					|
       |				  |					k      |					|
       |				  |					A      |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					A      |					|
       |				  |					d      |					|
       |				  |					       |					|
       |				  |					k      |					|
       |				  |					A      |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_ONE_MINUS_DST_ALPHA		  | 1					       | 1					|
       |				  |					1      |				 -	|
       |				  |					1      |					|
       |				  |					       |				     A	|
       |				  |				    -	       |				     d	|
       |				  |					       |					|
       |				  |					       |				     k	|
       |				  |					    A  |				     A	|
       |				  |					    d  |					|
       |				  |					       |					|
       |				  |					    k  |					|
       |				  |					    A  |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					    A  |					|
       |				  |					    d  |					|
       |				  |					       |					|
       |				  |					    k  |					|
       |				  |					    A  |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					    A  |					|
       |				  |					    d  |					|
       |				  |					       |					|
       |				  |					    k  |					|
       |				  |					    A  |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_CONSTANT_COLOR		  | R					       | A					|
       |				  |				    c	       |			     c		|
       |				  |					       |					|
       |				  |				    G	       |					|
       |				  |				    c	       |					|
       |				  |					       |					|
       |				  |				    B	       |					|
       |				  |				    c	       |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_ONE_MINUS_CONSTANT_COLOR	  | 1					       | 1					|
       |				  |					1      |				 -	|
       |				  |					1      |				 A	|
       |				  |					       |				 c	|
       |				  |				    -	       |					|
       |				  |					       |					|
       |				  |					R      |					|
       |				  |					c      |					|
       |				  |					       |					|
       |				  |					G      |					|
       |				  |					c      |					|
       |				  |					       |					|
       |				  |					B      |					|
       |				  |					c      |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_CONSTANT_ALPHA		  | A					       | A					|
       |				  |				    c	       |			     c		|
       |				  |					       |					|
       |				  |				    A	       |					|
       |				  |				    c	       |					|
       |				  |					       |					|
       |				  |				    A	       |					|
       |				  |				    c	       |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_ONE_MINUS_CONSTANT_ALPHA	  | 1					       | 1					|
       |				  |					1      |				 -	|
       |				  |					1      |				 A	|
       |				  |					       |				 c	|
       |				  |				    -	       |					|
       |				  |					       |					|
       |				  |					A      |					|
       |				  |					c      |					|
       |				  |					       |					|
       |				  |					A      |					|
       |				  |					c      |					|
       |				  |					       |					|
       |				  |					A      |					|
       |				  |					c      |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_SRC_ALPHA_SATURATE		  | i					       | 1					|
       |				  |				    i	       |					|
       |				  |				    i	       |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_SRC1_COLOR			  | R					       | A					|
       |				  |					s1     |				 s1	|
       |				  |					       |					|
       |				  |					k      |				 k	|
       |				  |					R      |				 A	|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					G      |					|
       |				  |					s1     |					|
       |				  |					       |					|
       |				  |					k      |					|
       |				  |					G      |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					B      |					|
       |				  |					s1     |					|
       |				  |					       |					|
       |				  |					k      |					|
       |				  |					B      |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_ONE_MINUS_SRC_COLOR		  | 1					       | 1					|
       |				  |					1      |				 -	|
       |				  |					1      |					|
       |				  |					1      |				     A	|
       |				  |					       |				     s1 |
       |				  |				    -	       |					|
       |				  |					       |				     k	|
       |				  |					       |				     A	|
       |				  |					    R  |					|
       |				  |					    s1 |					|
       |				  |					       |					|
       |				  |					    k  |					|
       |				  |					    R  |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					    G  |					|
       |				  |					    s1 |					|
       |				  |					       |					|
       |				  |					    k  |					|
       |				  |					    G  |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					    B  |					|
       |				  |					    s1 |					|
       |				  |					       |					|
       |				  |					    k  |					|
       |				  |					    B  |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_SRC1_ALPHA			  | A					       | A					|
       |				  |					s1     |				 s1	|
       |				  |					       |					|
       |				  |					k      |				 k	|
       |				  |					A      |				 A	|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					A      |					|
       |				  |					s1     |					|
       |				  |					       |					|
       |				  |					k      |					|
       |				  |					A      |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					A      |					|
       |				  |					s1     |					|
       |				  |					       |					|
       |				  |					k      |					|
       |				  |					A      |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+
       |GL_ONE_MINUS_SRC_ALPHA		  | 1					       | 1					|
       |				  |					1      |				 -	|
       |				  |					1      |					|
       |				  |					       |				     A	|
       |				  |				    -	       |				     s1 |
       |				  |					       |					|
       |				  |					       |				     k	|
       |				  |					    A  |				     A	|
       |				  |					    s1 |					|
       |				  |					       |					|
       |				  |					    k  |					|
       |				  |					    A  |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					    A  |					|
       |				  |					    s1 |					|
       |				  |					       |					|
       |				  |					    k  |					|
       |				  |					    A  |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					       |					|
       |				  |					    A  |					|
       |				  |					    s1 |					|
       |				  |					       |					|
       |				  |					    k  |					|
       |				  |					    A  |					|
       +----------------------------------+--------------------------------------------+----------------------------------------+

       In the table,

       To determine the blended RGBA values of a pixel, the system uses the following equations:

       Despite the apparent precision of the above equations, blending arithmetic is not exactly
       specified, because blending operates with imprecise integer color values. However, a blend
       factor that should be equal to 1 is guaranteed not to modify its multiplicand, and a blend
       factor equal to 0 reduces its multiplicand to 0. For example, when srcRGB is GL_SRC_ALPHA,
       dstRGB is GL_ONE_MINUS_SRC_ALPHA, and A s is equal to k A, the equations reduce to simple
       replacement:

NOTES
       Incoming (source) alpha is correctly thought of as a material opacity, ranging from 1.0 (K
       A), representing complete opacity, to 0.0(0), representing complete transparency.

       When more than one color buffer is enabled for drawing, the GL performs blending
       separately for each enabled buffer, using the contents of that buffer for destination
       color. (See glDrawBuffer().)

       When dual source blending is enabled (i.e., one of the blend factors requiring the second
       color input is used), the maximum number of enabled draw buffers is given by
       GL_MAX_DUAL_SOURCE_DRAW_BUFFERS, which may be lower than GL_MAX_DRAW_BUFFERS.

ERRORS
       GL_INVALID_ENUM is generated if either srcRGB or dstRGB is not an accepted value.

       GL_INVALID_VALUE is generated by glBlendFuncSeparatei if buf is greater than or equal to
       the value of GL_MAX_DRAW_BUFFERS.

ASSOCIATED GETS
       glGet() with argument GL_BLEND_SRC_RGB

       glGet() with argument GL_BLEND_SRC_ALPHA

       glGet() with argument GL_BLEND_DST_RGB

       glGet() with argument GL_BLEND_DST_ALPHA

       glIsEnabled() with argument GL_BLEND

SEE ALSO
       glBlendColor(), glBlendFunc(), glBlendEquation(), glClear(), glDrawBuffer(), glEnable(),
       glLogicOp(), glStencilFunc()

COPYRIGHT
       Copyright (C) 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI
       Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.

AUTHORS
       opengl.org

opengl.org				    06/10/2014			  GLBLENDFUNCSEPARATE(3G)
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