The WebGLRenderingContext.stencilFuncSeparate()
method of the WebGL API sets the front and/or 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.stencilFuncSeparate(face, func, ref, mask);
Parameters
- 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
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.stencilFuncSeparate(gl.FRONT, 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 'stencilFuncSeparate' in that specification. |
Recommendation | Initial definition. |
OpenGL ES 2.0 The definition of 'glStencilFuncSeparate' in that specification. |
Standard | Man page of the OpenGL API. |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | 9 | 4.0 (2.0) | 11 | 12 | 5.1 |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | ? | 25 | (Yes) | ? | 12 | 8.1 |