WebGLRenderingContext: vertexAttrib[1234]f[v]() method

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

The WebGLRenderingContext.vertexAttrib[1234]f[v]() methods of the WebGL API specify constant values for generic vertex attributes.

Syntax

vertexAttrib1f(index, v0)
vertexAttrib2f(index, v0, v1)
vertexAttrib3f(index, v0, v1, v2)
vertexAttrib4f(index, v0, v1, v2, v3)

vertexAttrib1fv(index, value)
vertexAttrib2fv(index, value)
vertexAttrib3fv(index, value)
vertexAttrib4fv(index, value)

Parameters

index: A GLuint specifying the position of the vertex attribute to be modified.
v0, v1, v2, v3: A floating point Number for the vertex attribute value.
value: A Float32Array for floating point vector vertex attribute values.

While vertex attributes are usually used to specify values which are different for each vertex (using vertexAttribPointer), it can be useful to specify a constant value. For example, if you have a shader which has a color vertex attribute, but you want to draw everything in a single color, you can use vertexAttrib to achieve that without creating a buffer filled with only one value or having to create a separate shader which uses a uniform for the color.

This value will be used if a bound array buffer has not been enabled with enableVertexAttribArray.

Attributes may be matrices, in which case columns of the matrix must be loaded into successive vertex attribute slots.

The values set with vertexAttrib are context-global; that is, they aren't part of the shader state (like generic vertex attribute indexes to shader variable bindings) and aren't part of the vertex array object state (like enabled vertex attribute arrays). The only way to change the values is by calling this function again.

Examples

const a_foobar = gl.getAttribLocation(shaderProgram, "foobar");
//either set each component individually:
gl.vertexAttrib3f(a_foobar, 10.0, 5.0, 2.0);
//or provide a Float32Array:
const floatArray = new Float32Array([10.0, 5.0, 2.0]);
gl.vertexAttrib3fv(a_foobar, floatArray);

// we want to load the following 3x3 matrix into attribute named "matrix3x3"
// 0 1 2
// 3 4 5
// 6 7 8
const matrix3x3Location = gl.getAttribLocation(shaderProgram, "matrix3x3");
gl.vertexAttrib3f(matrix3x3Location, 0, 3, 6);
gl.vertexAttrib3f(matrix3x3Location + 1, 1, 4, 7);
gl.vertexAttrib3f(matrix3x3Location + 2, 2, 5, 8);

Specifications

Specification
WebGL Specification # 5.14.10

Browser compatibility

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