GLAF
OpenGL Advanced Functionality

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Subtractive Blending availability test

GLboolean glaf_IsBlendSubtractSupported(void)

This function returns GL_TRUE if the feature is supported or GL_FALSE otherwise. Calling the functions of an unsupported feature or using its enumerants may crash the application, or generate OpenGL errors, or even undefined behaviour, so you should never use a feature without testing its availability first.
 

Subtractive Blending support rules

  • If we're running in OpenGL 1.2 or higher, and GL_ARB_imaging is supported, and the query of the address of the imaging functions is successful, the ARB imaging implementation is used.
  • Otherwise, if GL_EXT_blend_subtract is supported, and the query of the address of the extension functions is successful, this extension is used.
  • Otherwise, the feature is unsupported.


Subtractive Blending enumerants

(Add either a 'GLAF_' or 'GL_' prefix before each enumerant. GLAF enumerants are always defined, while GL ones depend on the version of your include files).

FUNC_ADD    
FUNC_SUBTRACT   
FUNC_REVERSE_SUBTRACT   
BLEND_EQUATION   
 

Subtractive Blending functions

glaf_BlendEquation
 

Subtractive Blending definitions in 'gl2glaf.h' (optional)

#define glBlendEquation                 glaf_BlendEquation
 

Subtractive Blending side effects

None.

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Copyright (C) 2001 César Blecua Udías