WebGLRenderingContext.getActiveUniform()

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WebGLRenderingContext.getActiveUniform() 方法在 WebGL API 返回 WebGLActiveInfo object containing size, type, and name of a uniform attribute. It is generally used when querying unknown uniforms either for debugging or generic library creation.

句法

WebGLActiveInfo WebGLRenderingContext.getActiveUniform(program, index);

参数

program: WebGLProgram specifying the WebGL shader program from which to obtain the uniform variable's information.
index: GLuint specifying the index of the uniform attribute to get. This value is an index 0 to N - 1 as returned by gl.getProgramParameter(program, gl.ACTIVE_UNIFORMS) .

返回值

A WebGLActiveInfo object describing the uniform.

type attribute of the return value will be one of the following:

gl.FLOAT
gl.FLOAT_VEC2
gl.FLOAT_VEC3
gl.FLOAT_VEC4
gl.INT
gl.INT_VEC2
gl.INT_VEC3
gl.INT_VEC4
gl.BOOL
gl.BOOL_VEC2
gl.BOOL_VEC3
gl.BOOL_VEC4
gl.FLOAT_MAT2
gl.FLOAT_MAT3
gl.FLOAT_MAT4
gl.SAMPLER_2D
gl.SAMPLER_CUBE
当使用 WebGL 2 context , the following values are possible additionally:
- gl.UNSIGNED_INT
- gl.UNSIGNED_INT_VEC2
- gl.UNSIGNED_INT_VEC3
- gl.UNSIGNED_INT_VEC4
- gl.FLOAT_MAT2x3
- gl.FLOAT_MAT2x4
- gl.FLOAT_MAT3x2
- gl.FLOAT_MAT3x4
- gl.FLOAT_MAT4x2
- gl.FLOAT_MAT4x3
- gl.SAMPLER_2D
- gl.SAMPLER_3D
- gl.SAMPLER_CUBE
- gl.SAMPLER_2D_SHADOW
- gl.SAMPLER_2D_ARRAY
- gl.SAMPLER_2D_ARRAY_SHADOW
- gl.SAMPLER_CUBE_SHADOW
- gl.INT_SAMPLER_2D
- gl.INT_SAMPLER_3D
- gl.INT_SAMPLER_CUBE
- gl.INT_SAMPLER_2D_ARRAY
- gl.UNSIGNED_INT_SAMPLER_2D
- gl.UNSIGNED_INT_SAMPLER_3D
- gl.UNSIGNED_INT_SAMPLER_CUBE
- gl.UNSIGNED_INT_SAMPLER_2D_ARRAY

当 gl.linkProgram is called, WebGL creates a list of active uniforms. These are possible values of the 名称 attribute of return values of getActiveUniform . WebGL generates one or more entries in the list depending on the declared type of the uniform in the shader:

Single basic type: one entry with the name of the uniform. E.g. uniform vec4 a; will result in a .
Array of basic type: one entry with the name of the uniform suffixed with [0] . E.g. uniform vec4 b[]; will result in b[0] .
Struct type: one entry for each member of the struct. E.g. uniform struct { float foo; vec4 bar; } c; will result in c.foo and c.bar .
Arrays of structs or arrays: each entry of the array will generate its own entries. E.g. uniform struct { float foo; vec4 bar; } d[2]; will result in:
- d[0].foo
- d[0].bar
- d[1].foo
- d[1].bar
Uniform blocks: one entry for each member. If the uniform block has an instance name, the block name is prefixed. E.g. uniform Block { float foo; }; will result in foo ，和 uniform Block { float bar; } e; will result in Block.bar .

size attribute of the return value corresponds to the length of the array for uniforms declared as arrays. Otherwise, it is 1 (this includes interface blocks instanced with arrays).

异常

gl.INVALID_VALUE is generated if the program WebGLProgram is invalid (not linked, deleted, etc.).
gl.INVALID_VALUE is generated if index is not in the range [0, gl.getProgramParameter(program, gl.ACTIVE_UNIFORMS) - 1].

范例

const numUniforms = gl.getProgramParameter(program, gl.ACTIVE_UNIFORMS);
for (let i = 0; i < numUniforms; ++i) {
  const info = gl.getActiveUniform(program, i);
  console.log('name:', info.name, 'type:', info.type, 'size:', info.size);
}

规范

规范	状态	注释
WebGL 1.0 The definition of 'getActiveUniform' in that specification.	推荐	初始定义。
OpenGL ES 2.0 The definition of 'glGetActiveUniform' in that specification.	标准	Man page of the OpenGL API.

浏览器兼容性

更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`getActiveUniform`	Chrome 9	Edge 12	Firefox 4	IE 11	Opera 12	Safari 5.1	WebView Android Yes	Chrome Android 25	Firefox Android Yes	Opera Android 12	Safari iOS 8	Samsung Internet Android 1.5

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