GLBLENDEQUATIONSEPAR(3G) OpenGL 3.3 GLBLENDEQUATIONSEPAR(3G)
NAME
glBlendEquationSeparate - set the RGB blend equation and the alpha blend equation separately
C SPECIFICATION
void glBlendEquationSeparate(GLenum modeRGB, GLenum modeAlpha);
PARAMETERS
modeRGB
specifies the RGB blend equation, how the red, green, and blue components of the source and destination colors are combined. It must be
GL_FUNC_ADD, GL_FUNC_SUBTRACT, GL_FUNC_REVERSE_SUBTRACT, GL_MIN, GL_MAX.
modeAlpha
specifies the alpha blend equation, how the alpha component of the source and destination colors are combined. It must be GL_FUNC_ADD,
GL_FUNC_SUBTRACT, GL_FUNC_REVERSE_SUBTRACT, GL_MIN, GL_MAX.
DESCRIPTION
The blend equations determines how a new pixel (the ''source'' color) is combined with a pixel already in the framebuffer (the
''destination'' color). This function specifies one blend equation for the RGB-color components and one blend equation for the alpha
component.
The blend equations use the source and destination blend factors specified by either glBlendFunc() or glBlendFuncSeparate(). See
glBlendFunc() or glBlendFuncSeparate() for a description of the various blend factors.
In the equations that follow, source and destination color components are referred to as R s G s B s A s and R d G d B d A d, respectively.
The result color is referred to as R r G r B r A r. The source and destination blend factors are denoted s R s G s B s A and d R d G d B d
A, respectively. For these equations all color components are understood to have values in the range 0 1.
+-----------------------------+-----------------------------------------------------+-----------------------------------------------------+
| | | |
| Mode | RGB | Alpha |
| | Components | Component |
| | | |
+-----------------------------+-----------------------------------------------------+-----------------------------------------------------+
|GL_FUNC_ADD | <div> | <div> |
| | | |
| | | |
| | Rr | Ar |
| | = | = |
| | | |
| | R | A |
| | s | s |
| | | |
| | | |
| | s | s |
| | R | A |
| | | |
| | + | + |
| | R | A |
| | d | d |
| | | |
| | | |
| | d | d |
| | R | A |
| | | |
| | | |
| | | |
| | </div> | </div> |
| | <div> | |
| | | |
| | | |
| | Gr | |
| | = | |
| | | |
| | G | |
| | s | |
| | | |
| | | |
| | s | |
| | G | |
| | | |
| | + | |
| | G | |
| | d | |
| | | |
| | | |
| | d | |
| | G | |
| | | |
| | | |
| | | |
| | </div> | |
| | <div> | |
| | | |
| | | |
| | Br | |
| | = | |
| | | |
| | B | |
| | s | |
| | | |
| | | |
| | s | |
| | B | |
| | | |
| | + | |
| | B | |
| | d | |
| | | |
| | | |
| | d | |
| | B | |
| | | |
| | | |
| | | |
| | </div> | |
+-----------------------------+-----------------------------------------------------+-----------------------------------------------------+
|GL_FUNC_SUBTRACT | <div> | <div> |
| | | |
| | | |
| | Rr | Ar |
| | = | = |
| | | |
| | R | A |
| | s | s |
| | | |
| | | |
| | s | s |
| | R | A |
| | | |
| | - | - |
| | R | A |
| | d | d |
| | | |
| | | |
| | d | d |
| | R | A |
| | | |
| | | |
| | | |
| | </div> | </div> |
| | <div> | |
| | | |
| | | |
| | Gr | |
| | = | |
| | | |
| | G | |
| | s | |
| | | |
| | | |
| | s | |
| | G | |
| | | |
| | - | |
| | G | |
| | d | |
| | | |
| | | |
| | d | |
| | G | |
| | | |
| | | |
| | | |
| | </div> | |
| | <div> | |
| | | |
| | | |
| | Br | |
| | = | |
| | | |
| | B | |
| | s | |
| | | |
| | | |
| | s | |
| | B | |
| | | |
| | - | |
| | B | |
| | d | |
| | | |
| | | |
| | d | |
| | B | |
| | | |
| | | |
| | | |
| | </div> | |
+-----------------------------+-----------------------------------------------------+-----------------------------------------------------+
|GL_FUNC_REVERSE_SUBTRACT | <div> | <div> |
| | | |
| | | |
| | Rr | Ar |
| | = | = |
| | | |
| | R | A |
| | d | d |
| | | |
| | | |
| | d | d |
| | R | A |
| | | |
| | - | - |
| | R | A |
| | s | s |
| | | |
| | | |
| | s | s |
| | R | A |
| | | |
| | | |
| | | |
| | </div> | </div> |
| | <div> | |
| | | |
| | | |
| | Gr | |
| | = | |
| | | |
| | G | |
| | d | |
| | | |
| | | |
| | d | |
| | G | |
| | | |
| | - | |
| | G | |
| | s | |
| | | |
| | | |
| | s | |
| | G | |
| | | |
| | | |
| | | |
| | </div> | |
| | <div> | |
| | | |
| | | |
| | Br | |
| | = | |
| | | |
| | B | |
| | d | |
| | | |
| | | |
| | d | |
| | B | |
| | | |
| | - | |
| | B | |
| | s | |
| | | |
| | | |
| | s | |
| | B | |
| | | |
| | | |
| | | |
| | </div> | |
+-----------------------------+-----------------------------------------------------+-----------------------------------------------------+
|GL_MIN | <div> | <div> |
| | | |
| | | |
| | Rr | Ar |
| | = | = |
| | | |
| | min | min |
| | | |
| | | |
| | | |
| | R | A |
| | s | s |
| | | |
| | | |
| | | |
| | R | A |
| | d | d |
| | | |
| | | |
| | | |
| | | |
| | | |
| | </div> | </div> |
| | <div> | |
| | | |
| | | |
| | Gr | |
| | = | |
| | | |
| | min | |
| | | |
| | | |
| | | |
| | G | |
| | s | |
| | | |
| | | |
| | | |
| | G | |
| | d | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | </div> | |
| | <div> | |
| | | |
| | | |
| | Br | |
| | = | |
| | | |
| | min | |
| | | |
| | | |
| | | |
| | B | |
| | s | |
| | | |
| | | |
| | | |
| | B | |
| | d | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | </div> | |
+-----------------------------+-----------------------------------------------------+-----------------------------------------------------+
|GL_MAX | <div> | <div> |
| | | |
| | | |
| | Rr | Ar |
| | = | = |
| | | |
| | max | max |
| | | |
| | | |
| | | |
| | R | A |
| | s | s |
| | | |
| | | |
| | | |
| | R | A |
| | d | d |
| | | |
| | | |
| | | |
| | | |
| | | |
| | </div> | </div> |
| | <div> | |
| | | |
| | | |
| | Gr | |
| | = | |
| | | |
| | max | |
| | | |
| | | |
| | | |
| | G | |
| | s | |
| | | |
| | | |
| | | |
| | G | |
| | d | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | </div> | |
| | <div> | |
| | | |
| | | |
| | Br | |
| | = | |
| | | |
| | max | |
| | | |
| | | |
| | | |
| | B | |
| | s | |
| | | |
| | | |
| | | |
| | B | |
| | d | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | </div> | |
+-----------------------------+-----------------------------------------------------+-----------------------------------------------------+
The results of these equations are clamped to the range 0 1.
The GL_MIN and GL_MAX equations are useful for applications that analyze image data (image thresholding against a constant color, for
example). The GL_FUNC_ADD equation is useful for antialiasing and transparency, among other things.
Initially, both the RGB blend equation and the alpha blend equation are set to GL_FUNC_ADD.
NOTES
The GL_MIN, and GL_MAX equations do not use the source or destination factors, only the source and destination colors.
ERRORS
GL_INVALID_ENUM is generated if either modeRGB or modeAlpha is not one of GL_FUNC_ADD, GL_FUNC_SUBTRACT, GL_FUNC_REVERSE_SUBTRACT, GL_MAX,
or GL_MIN.
ASSOCIATED GETS
glGet() with an argument of GL_BLEND_EQUATION_RGB
glGet() with an argument of GL_BLEND_EQUATION_ALPHA
SEE ALSO
glGetString(), glBlendColor(), glBlendFunc(), glBlendFuncSeparate()
COPYRIGHT
Copyright (C) 2006 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication
License, v 1.0, 8 June 1999. http://opencontent.org/openpub/.
OpenGL 3.3 03/08/2011 GLBLENDEQUATIONSEPAR(3G)