OES_draw_buffers_indexed: blendEquationiOES() method
The blendEquationiOES()
method of the OES_draw_buffers_indexed
WebGL extension sets both the RGB blend and alpha blend equations for a particular draw buffer.
See OES_draw_buffers_indexed.blendEquationSeparateiOES()
for setting RGB and alpha separately and WebGLRenderingContext.blendEquation()
for the WebGL 1 version of this method.
Syntax
js
blendEquationiOES(buf, mode)
Parameters
buf
-
An integer
i
specifying the draw buffer associated with the constantgl.DRAW_BUFFERi
, see WebGL draw buffer constants. mode
-
A
GLenum
specifying how source and destination colors are combined. Accepts the same enums as themode
parameter inWebGLRenderingContext.blendEquation()
.
Return value
None (undefined
).
Exceptions
- If
buf
is not a valid value, agl.INVALID_VALUE
error is thrown. - If
mode
is not one of the possible values, agl.INVALID_ENUM
error is thrown.
Examples
Setting and getting blend equations
You can set the blend equations for the gl.DRAW_BUFFER0
and gl.DRAW_BUFFER1
draw buffers like this:
js
const ext = gl.getExtension("OES_draw_buffers_indexed");
ext.blendEquationiOES(0, gl.FUNC_ADD);
ext.blendEquationiOES(1, gl.FUNC_SUBTRACT);
To get the blend equations for the gl.DRAW_BUFFER0
and gl.DRAW_BUFFER1
draw buffers, 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_BUFFER0
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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