OES_draw_buffers_indexed: blendEquationSeparateiOES() method
Baseline 2022
Newly available
Since December 2022, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.
The blendEquationSeparateiOES()
method of the OES_draw_buffers_indexed
WebGL extension sets the RGB and alpha blend equations separately for a particular draw buffer.
See OES_draw_buffers_indexed.blendEquationiOES()
for setting RGB and alpha together and WebGLRenderingContext.blendEquationSeparate()
for the WebGL 1 version of this method.
Syntax
blendEquationSeparateiOES(buf, modeRGB, modeAlpha)
Parameters
buf
-
An integer
i
specifying the draw buffer associated with the constantgl.DRAW_BUFFERi
, see WebGL draw buffer constants. modeRGB
-
A
GLenum
specifying how source and destination RGB color components are combined. Accepts the same enums as themodeRGB
parameter inWebGLRenderingContext.blendEquationSeparate()
. modeAlpha
-
A
GLenum
specifying how source and destination alpha color components are combined. Accepts the same enums as themodeAlpha
parameter inWebGLRenderingContext.blendEquationSeparate()
.
Return value
None (undefined
).
Exceptions
- If
buf
is not a valid value, agl.INVALID_VALUE
error is thrown. - If
modeRGB
ormodeAlpha
are not set to one of the possible values, agl.INVALID_ENUM
error is thrown.
Examples
Setting and getting blend equations
The following sets the blend equations for the draw buffers gl.DRAW_BUFFER0
(call where buf
is 0) and gl.DRAW_BUFFER1
(call where buf
is 1).
const ext = gl.getExtension("OES_draw_buffers_indexed");
ext.blendEquationSeparateiOES(0, gl.FUNC_ADD, gl.FUNC_SUBTRACT);
ext.blendEquationSeparateiOES(1, gl.FUNC_ADD, gl.FUNC_SUBTRACT);
To get the blend equations for gl.DRAW_BUFFER0
and gl.DRAW_BUFFER1
, query the BLEND_EQUATION_RGB
and BLEND_EQUATION_ALPHA
constants using WebGL2RenderingContext.getIndexedParameter()
:
// For gl.DRAW_BUFFER0
gl.getIndexedParameter(gl.BLEND_EQUATION_RGB, 0);
gl.getIndexedParameter(gl.BLEND_EQUATION_ALPHA, 0);
// for gl.DRAW_BUFFER1
gl.getIndexedParameter(gl.BLEND_EQUATION_RGB, 1);
gl.getIndexedParameter(gl.BLEND_EQUATION_ALPHA, 1);
Specifications
Specification |
---|
WebGL OES_draw_buffers_indexed Extension Specification |
Browser compatibility
BCD tables only load in the browser