swizzling

Swizzling is a technique used in vector-based programming to rearrange or replicate the components of a vector or color value by selecting a permutation of its channels. It enables constructing new vectors from existing ones and manipulating individual components in a concise, readable way, often without creating intermediate temporaries.

In graphics and shading languages, swizzling is a common feature of vector types such as 2D, 3D, and 4D vectors. Languages like GLSL and HLSL expose swizzle operations that let programmers access components by letters that represent channels, such as x, y, z, w or r, g, b, a. Examples include extracting a subset or reordering components, for instance v.xyz to form a three-component vector from v, or v.yzx to permute the channels. Some languages also support replication, where a single component is broadcast to multiple positions, such as v.xx or v.rgb.

Swizzling is widely used for color manipulation, texture coordinate handling, and vector math, as it reduces the need for explicit component-wise construction and can improve code clarity. It can also help optimize shader performance by avoiding temporary variables in many cases.

Portability and restrictions vary by language and hardware. While swizzling is ubiquitous in modern shading languages, its exact syntax, the set of permitted operations, and rules about assignment to swizzled components differ. Programmers should consult the target language specification to understand allowed patterns and any potential portability considerations.