WebGLRenderingContext.isEnabled()
WebGLRenderingContext.isEnabled()
是 WebGL API 方法之一,用来检测给定的 WebGL 功能项在当前上下文是否可用。
默认的,除了 gl.DITHER
,所有的功能项都是未启用的。
句法
void gl.isEnabled(cap);
参数
cap
-
GLenum
(en-US) 指定待检测的 WebGL 功能项。可能的值有:Constant Description gl.BLEND
Blending of the computed fragment color values. See WebGLRenderingContext.blendFunc()
.gl.CULL_FACE
Culling of polygons. See WebGLRenderingContext.cullFace()
.gl.DEPTH_TEST
Depth comparisons and updates to the depth buffer. See WebGLRenderingContext.depthFunc()
.gl.DITHER
Dithering of color components before they get written to the color buffer. gl.POLYGON_OFFSET_FILL
Adding an offset to depth values of polygon's fragments. See WebGLRenderingContext.polygonOffset()
.gl.SAMPLE_ALPHA_TO_COVERAGE
Computation of a temporary coverage value determined by the alpha value. gl.SAMPLE_COVERAGE
ANDing the fragment's coverage with the temporary coverage value. See WebGLRenderingContext.sampleCoverage()
(en-US).gl.SCISSOR_TEST
Scissor test that discards fragments that are outside of the scissor rectangle. See WebGLRenderingContext.scissor()
.gl.STENCIL_TEST
Stencil testing and updates to the stencil buffer. See WebGLRenderingContext.stencilFunc()
(en-US).当使用 WebGL 2 context 的时候,下列附加的值也是可选用的。
Constant Description gl.RASTERIZER_DISCARD
Primitives are discarded immediately before the rasterization stage, but after the optional transform feedback stage. gl.clear()
commands are ignored.
返回值
GLboolean
(en-US) 指示能力项 cap 可用 (true
),不可用 (false
)。
示例
gl.isEnabled(gl.STENCIL_TEST);
// false
启用或停用给定的能力项,使用 WebGLRenderingContext.enable()
方法和 WebGLRenderingContext.disable()
方法:
gl.enable(gl.STENCIL_TEST);
gl.disable(gl.STENCIL_TEST);
规范
Specification |
---|
WebGL Specification # 5.14.3 |
WebGL 2.0 Specification # 3.7.2 |
浏览器兼容性
BCD tables only load in the browser