vec4

vec4 is a four-component vector type used in GLSL, the OpenGL Shading Language, and in related shading languages. It represents a vector of four 32-bit floating-point numbers and is commonly used to store positions, directions, colors, or homogeneous coordinates in 3D graphics.

Each component of a vec4 is named x, y, z, and w, though the same storage is frequently addressed as r, g, b, and a when working with colors. Swizzling allows convenient access and reordering of components, such as v.xyz or v.rgba.

Constructors and representations include several forms: vec4(x, y, z, w); vec4(v3, w) where v3 is a vec3; vec4(v2, z, w) where v2 is a vec2; and vec4(s) which replicates a scalar to all components. A default vec4() yields (0.0, 0.0, 0.0, 0.0).

Vector operations follow standard rules: vec4 supports addition, subtraction, scalar multiplication, and equality testing. GLSL provides functions such as dot(v1, v2), length(v), and normalize(v). Cross product is defined for vec3, but vec4 can participate in homogeneous-coordinate math when used with appropriate conventions.

Common usage includes representing a position in homogeneous coordinates (often with w = 1.0 for points in world or clip space), colors with alpha in graphics pipelines, or four-component data in vertex attributes and shader uniforms. Memory layout for vec4 is typically 16 bytes, making it convenient for alignment in buffers and uniforms.

Example: vec4 color = vec4(1.0, 0.5, 0.0, 1.0); vec4 pos = vec4(vertex.xyz, 1.0).