void glBlendEquationSeparate(GLenum modeRGB, GLenum modeAlpha);
void glBlendEquationSeparatei(GLuint buf, GLenum modeRGB, GLenum modeAlpha);
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 Components||Alpha Component|
|GL_FUNC_ADD||Rr = R s s R + R d d R Gr = G s s G + G d d G Br = B s s B + B d d B||Ar = A s s A + A d d A|
|GL_FUNC_SUBTRACT||Rr = R s s R - R d d R Gr = G s s G - G d d G Br = B s s B - B d d B||Ar = A s s A - A d d A|
|GL_FUNC_REVERSE_SUBTRACT||Rr = R d d R - R s s R Gr = G d d G - G s s G Br = B d d B - B s s B||Ar = A d d A - A s s A|
|GL_MIN||Rr = min R s R d Gr = min G s G d Br = min B s B d||Ar = min A s A d|
|GL_MAX||Rr = max R s R d Gr = max G s G d Br = max B s B d||Ar = max A s A d|
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.
GL_INVALID_VALUE is generated by glBlendEquationSeparatei if buf is greater than or equal to the value of GL_MAX_DRAW_BUFFERS.
glGet() with an argument of GL_BLEND_EQUATION_ALPHA
|Function / Feature Name||2.0||2.1||3.0||3.1||3.2||3.3||4.0||4.1||4.2||4.3||4.4||4.5|
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