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glextensions - GL_EXT_blend_equation_separate.wiki

Contents

  • Dependencies
  • Overview
  • New Procedures and Functions
  • New Tokens
  • Errors
  • New State
  • New Implementation Dependent State

Dependencies

Written based on the wording of the OpenGL 1.5 specification.

OpenGL 1.4 (or GL_ARB_imaging, or GL_EXT_blend_minmax and/or GL_EXT_blend_subtract) is required for blend equation support.

GL_EXT_blend_func_separate is presumed but not required.

GL_EXT_blend_logic_op interacts with this extension.

Overview

GL_EXT_blend_func_separate introduced separate RGB and alpha blend factors. GL_EXT_blend_minmax introduced a distinct blend equation for combining source and destination blend terms. (GL_EXT_blend_subtract & GL_EXT_blend_logic_op added other blend equation modes.) OpenGL 1.4 integrated both functionalities into the core standard.

While there are separate blend functions for the RGB and alpha blend factors, OpenGL 1.4 provides a single blend equation that applies to both RGB and alpha portions of blending.

This extension provides a separate blend equation for RGB and alpha to match the generality available for blend factors.

New Procedures and Functions

void BlendEquationSeparateEXT(enum modeRGB, enum modeAlpha);

New Tokens

Accepted by the

<pname>

parameter of GetBooleanv, GetIntegerv, GetFloatv, and GetDoublev:

|BLEND_EQUATION_RGB_EXT | 0x8009 (same as BLEND_EQUATION)| |:-------------------------------|:-------------------------------------| |BLEND_EQUATION_ALPHA_EXT | 0x883D |

Errors

INVALID_ENUM is generated if either the modeRGB or modeAlpha parameter of BlendEquationSeparateEXT is not one of FUNC_ADD, FUNC_SUBTRACT, FUNC_REVERSE_SUBTRACT, MAX, or MIN.

INVALID_OPERATION is generated if BlendEquationSeparateEXT is executed between the execution of Begin and the corresponding execution of End.

New State

| Get Value | Get Command | Type | Initial Value | |:--------------|:----------------|:---------|:------------------| |BLEND_EQUATION_RGB_EXT|GetIntegerv |Z |FUNC_ADD | |BLEND_EQUATION_ALPHA_EXT|GetIntegerv |Z |FUNC_ADD |

New Implementation Dependent State

None