table of contents
GLBLENDEQUATION(3G) | [FIXME: manual] | GLBLENDEQUATION(3G) |
NAME¶
glBlendEquation - specify the equation used for both the RGB blend equation and the Alpha blend equationC SPECIFICATION¶
void
glBlendEquation(GLenum mode);
void
glBlendEquationi(GLuint buf,
GLenum mode);
PARAMETERS¶
buffor glBlendEquationi, specifies the
index of the draw buffer for which to set the blend equation.
mode
specifies how 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 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. glBlendEquationi specifies the blend equation for a single draw buffer whereas glBlendEquation sets the blend equation for all draw buffers. 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 | <div> Rr = R s s R + R d d R </div> <div> Gr = G s s G + G d d G </div> <div> Br = B s s B + B d d B </div> | <div> Ar = A s s A + A d d A </div> |
GL_FUNC_SUBTRACT | <div> Rr = R s s R - R d d R </div> <div> Gr = G s s G - G d d G </div> <div> Br = B s s B - B d d B </div> | <div> Ar = A s s A - A d d A </div> |
GL_FUNC_REVERSE_SUBTRACT | <div> Rr = R d d R - R s s R </div> <div> Gr = G d d G - G s s G </div> <div> Br = B d d B - B s s B </div> | <div> Ar = A d d A - A s s A </div> |
GL_MIN | <div> Rr = min R s R d </div> <div> Gr = min G s G d </div> <div> Br = min B s B d </div> | <div> Ar = min A s A d </div> |
GL_MAX | <div> Rr = max R s R d </div> <div> Gr = max G s G d </div> <div> Br = max B s B d </div> | <div> Ar = max A s A d </div> |
NOTES¶
The GL_MIN, and GL_MAX equations do not use the source or destination factors, only the source and destination colors.ERRORS¶
ASSOCIATED GETS¶
SEE ALSO¶
COPYRIGHT¶
Copyright © 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/.05/30/2012 | [FIXME: source] |