GLAPI/glBlendFunc: Difference between revisions

From OpenGL Wiki
Jump to navigation Jump to search
Centralizing information on blending, so that we don't need to put the same copied info in two places.
Redirect to the separate page.
 
Line 1: Line 1:
{{infobox feature
#REDIRECT [[GLAPI/glBlendFuncSeparate]]
| name = glBlendFunc
| core = 1.0
}}
 
'''glBlendFunc:''' specify pixel arithmetic
 
== Function Definition ==
 
  void '''glBlendFunc'''(GLenum {{param|sfactor}}, GLenum {{param|dfactor}});
  void '''glBlendFunci'''(GLuint {{param|buf}}, GLenum {{param|sfactor}}, GLenum {{param|dfactor}});
 
; buf
: For '''glBlendFunci''', specifies the index of the draw buffer for which to set the blend function.
; sfactor
: Specifies how the red, green, blue, and alpha source blending factors are computed. The initial value is {{enum|GL_ONE}}.
; dfactor
: Specifies how the red, green, blue, and alpha destination blending factors are computed. The following symbolic constants are accepted: {{enum|GL_ZERO}}, {{enum|GL_ONE}}, {{enum|GL_SRC_COLOR}}, {{enum|GL_ONE_MINUS_SRC_COLOR}}, {{enum|GL_DST_COLOR}}, {{enum|GL_ONE_MINUS_DST_COLOR}}, {{enum|GL_SRC_ALPHA}}, {{enum|GL_ONE_MINUS_SRC_ALPHA}}, {{enum|GL_DST_ALPHA}}, {{enum|GL_ONE_MINUS_DST_ALPHA}}. {{enum|GL_CONSTANT_COLOR}}, {{enum|GL_ONE_MINUS_CONSTANT_COLOR}}, {{enum|GL_CONSTANT_ALPHA}}, and {{enum|GL_ONE_MINUS_CONSTANT_ALPHA}}. The initial value is {{enum|GL_ZERO}}.
 
== Description ==
 
These functions operate as their more specific counterparts. '''glBlendFunc''' is equivalent to:
 
{{apifunc|glBlendFuncSeparate}}({{param|sfactor}}, {{param|dfactor}}, {{param|sfactor}}, {{param|dfactor}});
 
''glBlendFunci'' is equivalent to:
 
{{apifunc|glBlendFuncSeparate|i}}({{param|buf}}, {{param|sfactor}}, {{param|dfactor}}, {{param|sfactor}}, {{param|dfactor}});
 
== Notes ==
 
Incoming (source) alpha is correctly thought of as a material opacity, ranging from 1.0 (<math>k_A</math>), 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 {{apifunc|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 {{enum|GL_MAX_DUAL_SOURCE_DRAW_BUFFERS}}, which may be lower than {{enum|GL_MAX_DRAW_BUFFERS}}.
 
== Errors ==
 
{{enum|GL_INVALID_ENUM}} is generated if either {{param|sfactor}} or {{param|dfactor}} is not an accepted value.
 
{{enum|GL_INVALID_VALUE}} is generated by '''glBlendFunci''' if {{param|buf}} is greater than or equal to the value of {{enum|GL_MAX_DRAW_BUFFERS}}.
 
== Associated Gets ==
 
{{apifunc|glGet}} with argument {{enum|GL_BLEND_SRC}}
 
{{apifunc|glGet}} with argument {{enum|GL_BLEND_DST}}
 
{{apifunc|glIsEnabled}} with argument {{enum|GL_BLEND}}
 
 
 
== See Also ==
 
{{apifunc|glBlendColor}}, {{apifunc|glBlendEquation}}, {{apifunc|glBlendFuncSeparate}}, {{apifunc|glClear}}, {{apifunc|glDrawBuffer}}, {{apifunc|glEnable}}, {{apifunc|glLogicOp}}, {{apifunc|glStencilFunc}}
 
== 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/ http://oss.sgi.com/projects/FreeB/].


[[Category:Core API Ref Post Fragment Shader Operations|BlendFunc]]
[[Category:Core API Ref Post Fragment Shader Operations|BlendFunc]]
[[Category:Core API Reference|BlendFunc]]
[[Category:Core API Reference|BlendFunc]]

Latest revision as of 12:33, 27 August 2012