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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 constant gl.DRAW_BUFFERi, see WebGL draw buffer constants.

mode

A GLenum specifying how source and destination colors are combined. Accepts the same enums as the mode parameter in WebGLRenderingContext.blendEquation().

Return value

None (undefined).

Exceptions

  • If buf is not a valid value, a gl.INVALID_VALUE error is thrown.
  • If mode is not one of the possible values, a gl.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

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
blendEquationiOES 100 100 108 No 86 16 100 100 108 69 16 19.0

See also

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https://developer.mozilla.org/en-US/docs/Web/API/OES_draw_buffers_indexed/blendEquationiOES