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 1.0 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 compatibility
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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.