OES_draw_buffers_indexed: colorMaskiOES() method

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since December 2022.

The colorMaskiOES() method of the OES_draw_buffers_indexed WebGL extension sets which color components to enable or to disable when drawing or rendering for a particular draw buffer. It's the indexed version of WebGL 1's WebGLRenderingContext.colorMask() method.

Syntax

colorMaskiOES(buf, r, g, b, a)

Parameters

buf: An integer i specifying the draw buffer associated with the constant gl.DRAW_BUFFERi, see WebGL draw buffer constants.
r: A GLboolean specifying whether or not the red color component should be written into the draw buffer.
g: A GLboolean specifying whether or not the green color component should be written into the draw buffer.
b: A GLboolean specifying whether or not the blue color component should be written into the draw buffer.
a: A GLboolean specifying whether or not the red alpha (transparency) component should be written into the draw buffer.

Return value

None (undefined).

Exceptions

If buf, r, b, g, or a are not a valid values, a gl.INVALID_VALUE error is thrown.

Examples

Setting and getting color masks

You can set the color masks for the gl.DRAW_BUFFER0 and gl.DRAW_BUFFER1 draw buffers like this:

const ext = gl.getExtension("OES_draw_buffers_indexed");

ext.colorMaskiOES(0, 1, 0, 0, 0);
ext.colorMaskiOES(1, 0, 1, 0, 0);

To get the color masks for the gl.DRAW_BUFFER0 and gl.DRAW_BUFFER1 draw buffers, query the COLOR_WRITEMASK constant using WebGL2RenderingContext.getIndexedParameter():

gl.getIndexedParameter(gl.COLOR_WRITEMASK, 0);
gl.getIndexedParameter(gl.COLOR_WRITEMASK, 1);

Specifications

Specification
WebGL OES_draw_buffers_indexed Extension Specification