The WebGLRenderingContext.stencilFunc()
method of the WebGL API sets the front and back function and reference value for stencil testing.
Stencilling enables and disables drawing on a per-pixel basis. It is typically used in multipass rendering to achieve special effects.
Syntax
void gl.stencilFunc(func, ref, mask);
Parameters
func
- A
GLenum
specifying the test function. The default function isgl.ALWAYS
. The possible values are:gl.NEVER
: Never pass.gl.LESS
: Pass if(ref & mask) < (stencil & mask)
.gl.EQUAL
: Pass if(ref & mask) = (stencil & mask)
.gl.LEQUAL
: Pass if(ref & mask) <= (stencil & mask)
.gl.GREATER
: Pass if(ref & mask) > (stencil & mask)
.gl.NOTEQUAL
: Pass if(ref & mask) != (stencil & mask)
.gl.GEQUAL
: Pass if(ref & mask) >= (stencil & mask)
.gl.ALWAYS
: Always pass.
ref
- A
GLint
specifying the reference value for the stencil test. This value is clamped to the range 0 to 2n -1 where n is the number of bitplanes in the stencil buffer. The default value is 0. mask
- A
GLuint
specifying a bit-wise mask that is used to AND the reference value and the stored stencil value when the test is done. The default value is all 1.
Return value
None.
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.stencilFunc(gl.LESS, 0.2, 1110011);
To get the current stencil function, reference value, or other stencil information, query the following constants with getParameter()
.
gl.getParameter(gl.STENCIL_FUNC); gl.getParameter(gl.STENCIL_VALUE_MASK); gl.getParameter(gl.STENCIL_REF); gl.getParameter(gl.STENCIL_BACK_FUNC); gl.getParameter(gl.STENCIL_BACK_VALUE_MASK); gl.getParameter(gl.STENCIL_BACK_REF); gl.getParameter(gl.STENCIL_BITS);
Specifications
Specification | Status | Comment |
---|---|---|
WebGL 1.0 The definition of 'stencilFunc' in that specification. |
Recommendation | Initial definition. |
OpenGL ES 2.0 The definition of 'glStencilFunc' 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.
Feature | Chrome | Firefox | Edge | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic Support | 9 | 4.0 | 12 | 11 | 12 | 5.1 |
Feature | Android | Chrome for Android | Edge mobile | Firefox for Android | IE mobile | Opera Android | iOS Safari |
---|---|---|---|---|---|---|---|
Basic Support | (Yes) | 25 | (Yes) | (Yes) | 11 | 12 | 8.1 |