Web/API/WebGLRenderingContext/blendEquation

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.

Syntax

void gl.blendEquation(mode);

Parameters

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

Exception

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

Return value

None.

Examples

To set the blend equation, use:

gl.blendEquation(gl.FUNC_ADD);
gl.blendEquation(gl.FUNC_SUBTRACT);
gl.blendEquation(gl.FUNC_REVERSE_SUBTRACT);

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

Specifications

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

Browser compatibility

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`blendEquation`	Chrome Full support 9	Edge Full support 12	Firefox Full support 4	IE Full support 11	Opera Full support 12	Safari Full support 5.1	WebView Android Full support Yes	Chrome Android Full support 25	Firefox Android Full support Yes	Opera Android Full support 12	Safari iOS Full support 8	Samsung Internet Android Full support 1.5
`WebGL2`	Chrome Full support 56	Edge Full support 79	Firefox Full support 51	IE No support No	Opera Full support 43	Safari No support No	WebView Android Full support 58	Chrome Android Full support 58	Firefox Android Full support 51	Opera Android Full support 43	Safari iOS No support No	Samsung Internet Android Full support 7.0

Legend

Full support: Full support
No support: No support