WebGLRenderingContext: stencilOpSeparate() method
The WebGLRenderingContext.stencilOpSeparate()
method of
the WebGL API sets the front and/or
back-facing stencil test actions.
Syntax
js
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 isgl.KEEP
. zfail
-
A
GLenum
specifying the function to use when the stencil test passes, but the depth test fails. The default value isgl.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 isgl.KEEP
.
Return value
None (undefined
).
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
.
js
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()
.
js
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 |
---|
WebGL Specification # 5.14.3 |
Browser compatibility
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