WebGLRenderingContext: blendEquationSeparate() method
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
Note: This feature is available in Web Workers.
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
blendEquationSeparate(modeRGB, modeAlpha)
Parameters
modeRGB-
A
GLenumspecifying 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_minmaxextension: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
GLenumspecifying 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_minmaxextension: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 (undefined).
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 |
|---|
| WebGL Specification # 5.14.3 |
Browser compatibility
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