The blend equations determine how a new pixel (the ''source'' color) is combined with a pixel already in the framebuffer (the ''destination'' color). This function sets both the RGB blend equation and the alpha blend equation to a single equation. These 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. ModeRGB ComponentsAlpha ComponentGL_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.
The GL_MIN, and GL_MAX equations do not use the source or destination factors, only the source and destination colors.
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glBlendEquation: man2/glBlendEquation.xml
The blend equations determine how a new pixel (the ''source'' color) is combined with a pixel already in the framebuffer (the ''destination'' color). This function sets both the RGB blend equation and the alpha blend equation to a single equation. These 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.
The GL_MIN, and GL_MAX equations do not use the source or destination factors, only the source and destination colors.