WebGLRenderingContext.blendEquationSeparate()

The WebGLRenderingContext.blendEquationSeparate() method of the WebGL API is used to set the RGB blend equation and alpha blend equation separately.

The blend equation determines how a new pixel is combined with a pixel already in the WebGLFramebuffer.

Syntax

void gl.blendEquationSeparate(modeRGB, modeAlpha);

Parameters

modeRGB
A GLenum (en-US) specifying how the red, green and blue components of source and destination colors are combined. Must be either:
  • gl.FUNC_ADD: source + destination (default value),
  • gl.FUNC_SUBTRACT: source - destination,
  • gl.FUNC_REVERSE_SUBTRACT: destination - source,
  • When using the EXT_blend_minmax (en-US) extension:
    • ext.MIN_EXT: Minimum of source and destination,
    • ext.MAX_EXT: Maximum of source and destination.
  • When using a WebGL 2 context, the following values are available additionally:
    • gl.MIN: Minimum of source and destination,
    • gl.MAX: Maximum of source and destination.
modeAlpha
A GLenum (en-US) specifying how the alpha component (transparency) of source and destination colors are combined. Must be either:
  • gl.FUNC_ADD: source + destination (default value),
  • gl.FUNC_SUBTRACT: source - destination,
  • gl.FUNC_REVERSE_SUBTRACT: destination - source,
  • When using the EXT_blend_minmax (en-US) extension:
    • ext.MIN_EXT: Minimum of source and destination,
    • ext.MAX_EXT: Maximum of source and destination.
  • When using a WebGL 2 context, the following values are available additionally:
    • gl.MIN: Minimum of source and destination,
    • gl.MAX: Maximum of source and destination.

Return value

None.

Exceptions

If mode is not one of the three possible values, a gl.INVALID_ENUM error is thrown.

Examples

To set the blend equations, use:

gl.blendEquationSeparate(gl.FUNC_ADD, gl.FUNC_SUBTRACT);

To get the current blend equations, query the BLEND_EQUATION, BLEND_EQUATION_RGB and BLEND_EQUATION_ALPHA constants which return gl.FUNC_ADD, gl.FUNC_SUBTRACT, gl.FUNC_REVERSE_SUBTRACT, or if the EXT_blend_minmax (en-US) is enabled: ext.MIN_EXT or ext.MAX_EXT.

gl.getParameter(gl.BLEND_EQUATION_RGB) === gl.FUNC_ADD;
// true

gl.getParameter(gl.BLEND_EQUATION_ALPHA) === gl.FUNC_ADD;
// true

Specifications

Specification Status Comment
WebGL 1.0
blendEquationSeparate
Recommendation Initial definition for WebGL.
OpenGL ES 2.0
glBlendEquationSeparate
Standard Man page of the OpenGL ES 2.0 API.
OpenGL ES 3.0
glBlendEquationSeparate
Standard Man page of the OpenGL ES 3.0 API.

Browser compatibility

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See also