WebGL2RenderingContext: vertexAttribIPointer() method
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2021.
Note: This feature is available in Web Workers.
The WebGL2RenderingContext.vertexAttribIPointer()
method
of the WebGL 2 API specifies integer data
formats and locations of vertex attributes in a vertex attributes array.
Syntax
vertexAttribIPointer(index, size, type, stride, offset)
Parameters
index
-
A
GLuint
specifying the index of the vertex attribute that is to be modified. size
-
A
GLint
specifying the number of components per vertex attribute. Must be 1, 2, 3, or 4. type
-
A
GLenum
specifying the data type of each component in the array. Must be one of:gl.BYTE
,gl.UNSIGNED_BYTE
,gl.SHORT
,gl.UNSIGNED_SHORT
,gl.INT
, orgl.UNSIGNED_INT
. stride
-
A
GLsizei
specifying the offset in bytes between the beginning of consecutive vertex attributes. offset
-
A
GLintptr
specifying an offset in bytes of the first component in the vertex attribute array. Must be a multiple oftype
.
Return value
None (undefined
).
Description
Very similar to WebGLRenderingContext.vertexAttribPointer()
. The main
difference is that while values specified by vertexAttribPointer
are
always interpreted as floating-point values in the shader (even if they were originally
specified as integers in the buffer), this method allows specifying values which are
interpreted as integers in the shader.
Examples
Linear Blend Skinning
//Describe the layout of the buffer:
//1. position
gl.vertexAttribPointer(0, 3, gl.FLOAT, false, 20, 0);
gl.enableVertexAttribArray(0);
//2. bone weights, normalized to [0, 1]
gl.vertexAttribPointer(1, 4, gl.UNSIGNED_BYTE, true, 20, 12);
gl.enableVertexAttribArray(1);
//3. bone indices, interpreted as integer
gl.vertexAttribIPointer(2, 4, gl.UNSIGNED_BYTE, 20, 16);
gl.enableVertexAttribArray(2);
//Connect to attributes from the vertex shader
gl.bindAttribLocation(shaderProgram, 0, "position");
gl.bindAttribLocation(shaderProgram, 1, "boneWeights");
gl.bindAttribLocation(shaderProgram, 2, "boneIndices");
<script id="shader-vs" type="x-shader/x-vertex">
#version 300 es
uniform mat4 mvMatrix;
uniform mat4 bones[120];
in vec3 position;
in vec4 boneWeights;
in uvec4 boneIndices;//read as 4-component unsigned integer
void main() {
vec4 skinnedPosition =
bones[boneIndices.s] * vec4(position, 1.0) * boneWeights.s +
bones[boneIndices.t] * vec4(position, 1.0) * boneWeights.t +
bones[boneIndices.p] * vec4(position, 1.0) * boneWeights.p +
bones[boneIndices.q] * vec4(position, 1.0) * boneWeights.q;
gl_Position = mvMatrix * skinnedPosition;
}
</script>
Specifications
Specification |
---|
WebGL 2.0 Specification # 3.7.8 |
Browser compatibility
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