WebGLRenderingContext: blendEquation() 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.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
blendEquation(mode)
Parameters
mode
-
A
GLenum
specifying how source and destination colors are combined. Must be either:gl.FUNC_ADD
: source + destination (default value)gl.FUNC_SUBTRACT
: source - destinationgl.FUNC_REVERSE_SUBTRACT
: destination - source
When using the
EXT_blend_minmax
extension:ext.MIN_EXT
: Minimum of source and destinationext.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 destinationgl.MAX
: Maximum of source and destination
Exceptions
If mode is not one of the three possible values, a
gl.INVALID_ENUM
error is thrown.
Return value
None (undefined
).
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 |
---|
WebGL Specification # 5.14.3 |
Browser compatibility
BCD tables only load in the browser