OES_draw_buffers_indexed: blendEquationSeparateiOES() method
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
js
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).
js
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()
:
js
// 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
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