Web/API/WebGLRenderingContext/stencilOpSeparate

The WebGLRenderingContext.stencilOpSeparate() method of the WebGL API sets the front and/or back-facing stencil test actions.

Syntax

void gl.stencilOpSeparate(face, fail, zfail, zpass);

Parameters

The fail, zfail and zpass parameters accept all constants listed below.

face: A GLenum specifying whether the front and/or back stencil state is updated. The possible values are:

gl.FRONT gl.BACK gl.FRONT_AND_BACK

fail: A GLenum specifying the function to use when the stencil test fails. The default value is gl.KEEP.
zfail: A GLenum specifying the function to use when the stencil test passes, but the depth test fails. The default value is gl.KEEP.
zpass: A GLenum specifying the function to use when both the stencil test and the depth test pass, or when the stencil test passes and there is no depth buffer or depth testing is disabled. The default value is gl.KEEP.

Return value

None.

Constants

gl.KEEP: Keeps the current value.
gl.ZERO: Sets the stencil buffer value to 0.
gl.REPLACE: Sets the stencil buffer value to the reference value as specified by WebGLRenderingContext.stencilFunc().
gl.INCR: Increments the current stencil buffer value. Clamps to the maximum representable unsigned value.
gl.INCR_WRAP: Increments the current stencil buffer value. Wraps stencil buffer value to zero when incrementing the maximum representable unsigned value.
gl.DECR: Decrements the current stencil buffer value. Clamps to 0.
gl.DECR_WRAP: Decrements the current stencil buffer value. Wraps stencil buffer value to the maximum representable unsigned value when decrementing a stencil buffer value of 0.
gl.INVERT: Inverts the current stencil buffer value bitwise.

Examples

The stencil testing is disabled by default. To enable or disable stencil testing, use the enable() and disable() methods with the argument gl.STENCIL_TEST.

gl.enable(gl.STENCIL_TEST);
gl.stencilOpSeparate(gl.FRONT, gl.INCR, gl.DECR, gl.INVERT);

To get the current information about stencil and depth pass or fail, query the following constants with getParameter().

gl.getParameter(gl.STENCIL_FAIL);
gl.getParameter(gl.STENCIL_PASS_DEPTH_PASS);
gl.getParameter(gl.STENCIL_PASS_DEPTH_FAIL);
gl.getParameter(gl.STENCIL_BACK_FAIL);
gl.getParameter(gl.STENCIL_BACK_PASS_DEPTH_PASS);
gl.getParameter(gl.STENCIL_BACK_PASS_DEPTH_FAIL);
gl.getParameter(gl.STENCIL_BITS);

Specifications

Specification	Status	Comment
WebGL 1.0The definition of 'stencilOpSeparate' in that specification.	Recommendation	Initial definition.
OpenGL ES 2.0The definition of 'glStencilOpSeparate' in that specification.	Standard	Man page of the OpenGL API.

Browser compatibility

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`stencilOpSeparate`	Chrome Full support 9	Edge Full support 12	Firefox Full support 4	IE Full support 11	Opera Full support 12	Safari Full support 5.1	WebView Android Full support Yes	Chrome Android Full support 25	Firefox Android Full support Yes	Opera Android Full support 12	Safari iOS Full support 8	Samsung Internet Android Full support 1.5

Legend

Full support: Full support