WebGLRenderingContext.stencilOp()

The WebGLRenderingContext.stencilOp() method of the WebGL API sets both the front and back-facing stencil test actions.

Syntax

void gl.stencilOp(fail, zfail, zpass);

Parameters

All three parameters accept all constants listed below.

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.stencilOp(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 1.0
The definition of 'stencilOp' in that specification.
Recommendation Initial definition.
OpenGL ES 2.0
The definition of 'glStencilOp' in that specification.
Standard Man page of the OpenGL API.

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Basic supportChrome Full support 9Edge Full support 12Firefox Full support 4IE Full support 11Opera Full support 12Safari Full support 5.1WebView Android Full support YesChrome Android Full support 25Edge Mobile Full support YesFirefox Android Full support YesOpera Android Full support 12Safari iOS Full support 8.1Samsung Internet Android Full support Yes

Legend

Full support  
Full support

See also

Document Tags and Contributors

Contributors to this page: fscholz, teoli
Last updated by: fscholz,