The WebGLRenderingContext.blendEquation() method of the WebGL API is used to set both the RGB blend equation and alpha blend equation to a single equation.

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


void gl.blendEquation(mode);


A GLenum specifying how source and destination colors are combined. Must be either:
  • gl.FUNC_ADD: source + destination,
  • gl.FUNC_SUBTRACT: source - destination,
  • gl.FUNC_REVERSE_SUBTRACT: destination - source
  • When using the EXT_blend_minmax 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.

default value: gl.FUNC_ADD


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

Return value



To set the blend equation, use:


To get the 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 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


Specification Status Comment
WebGL 1.0
The definition of 'blendEquation' in that specification.
Recommendation Initial definition for WebGL.
OpenGL ES 2.0
The definition of 'glBlendEquation' in that specification.
Standard Man page of the OpenGL ES 2.0 API.
OpenGL ES 3.0
The definition of 'glBlendEquation' in that specification.
Standard Man page of the OpenGL ES 3.0 API.

Browser compatibilityUpdate compatibility data on GitHub

Chrome Edge Firefox Internet Explorer Opera Safari
Basic support 9 12 4 11 12 5.1
WebGL2 56 No 51 No 43 No
Android webview Chrome for Android Edge Mobile Firefox for Android Opera for Android iOS Safari Samsung Internet
Basic support Yes 25 Yes Yes 12 8.1 Yes
WebGL2 58 58 No 51 43 No 7.0

See also

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