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 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 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 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 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 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
The definition of 'blendEquationSeparate' in that specification.
Recommendation Initial definition for WebGL.
OpenGL ES 2.0
The definition of 'glBlendEquationSeparate' in that specification.
Standard Man page of the OpenGL ES 2.0 API.
OpenGL ES 3.0
The definition of 'glBlendEquationSeparate' in that specification.
Standard Man page of the OpenGL ES 3.0 API.

Browser compatibility

Feature Chrome Edge Firefox Internet Explorer Opera Safari Servo
Basic Support9124.011125.1No support
WebGL2No support1No support51.0No supportNo supportNo supportNo support
Feature Android Chrome for Android Edge Mobile Firefox for Android IE Mobile Opera Mobile Safari Mobile
Basic Support(Yes)25(Yes)4.0128.1
WebGL2No supportNo support(Yes)51.0No supportNo support

1. To use an experimental implementation of WebGL 2 in Chrome, you have to start Chrome with the runtime flag --enable-unsafe-es3-apis.

See also

Document Tags and Contributors

 Contributors to this page: teoli, fscholz
 Last updated by: teoli,