What is "swizzling"

vb. (present participle of swizzle English)

Swizzling may refer to:

• Pointer swizzling – a computer science term.
• Swizzling (computer graphics) – a computer graphics term.

In computer graphics, swizzling means rearranging the elements of a vector. For example, if A = {1,2,3,4}, where the components are x, y, z, and w respectively, you could compute B = A.wwxy, whereupon B would equal {4,4,1,2}. This is common in GPGPU applications.

In terms of linear algebra, this is equivalent to multiplying by a matrix whose rows are standard basis vectors. If A = (1, 2, 3, 4), then swizzling A as above looks like

$$A.wwxy = \begin{bmatrix} 0&0&0&1 \\ 0&0&0&1 \\ 1&0&0&0 \\ 0&1&0&0 \end{bmatrix}\begin{bmatrix} 1\\ 2\\ 3\\ 4\end{bmatrix} = \begin{bmatrix} 4\\ 4\\ 1\\ 2\end{bmatrix}$$
.