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
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 (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
BCD tables only load in the browser