WebGLRenderingContext.isEnabled() - Web APIs 编辑

The WebGLRenderingContext.isEnabled() method of the WebGL API tests whether a specific WebGL capability is enabled or not for this context.

By default, all capabilities except gl.DITHER are disabled.

Syntax

GLboolean gl.isEnabled(cap);

cap

A GLenum specifying which WebGL capability to test. Possible values:

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()`.
`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()`.

When using a WebGL 2 context, the following values are available additionally:

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.

A GLboolean indicating if the capability cap is enabled (true), or not (false).

gl.isEnabled(gl.STENCIL_TEST);
// false

To activate or deactivate a specific capability, use the WebGLRenderingContext.enable() and WebGLRenderingContext.disable() methods:

gl.enable(gl.STENCIL_TEST);
gl.disable(gl.STENCIL_TEST);

Specification	Status	Comment
WebGL 1.0 The definition of 'isEnabled' in that specification.	Recommendation	Initial definition for WebGL.
OpenGL ES 2.0 The definition of 'glIsEnabled' in that specification.	Standard	Man page of the (similar) OpenGL ES 2.0 API.
WebGL 2.0 The definition of 'isEnabled' in that specification.	Editor's Draft	Updated definition for WebGL 2.
OpenGL ES 3.0 The definition of 'glIsEnabled' in that specification.	Standard	Man page of the (similar) OpenGL ES 3.0 API.

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