Expressions Overview

An expression in WGSL is a sequence of operators and operands that evaluates to a value, type, function, or builtin enumerator. Value expressions are categorized by how they are structured, their typing rules, and the stages in which they are evaluated by the compiler and GPU.

Sections:

• Strict Typing: WGSL's "no implicit coercion" design, explicit type constructors, and compile-time type safety mechanisms.
• Operators Reference: Arithmetic, bitwise, logical, comparison, assignment, and compound assignment operators, with matrix/vector overloaded behaviors.
• Bitwise & Data Packing: Shift-and-mask bitwise operations for packing normal vectors and specular values into a single u32 to save G-buffer bandwidth.
• Evaluation Stages: Timeline of compilation stages, compile-time constant folding, and execution-time evaluation on the GPU.
  • Constant Stage: Expressions evaluated at compile time, including const declarations, compile-time boolean literals, and @const built-ins.
    • Numeric Literals: Abstract numeric types, base-10 and base-16 formats, hexadecimal float notation, and f16 half-precision float literals.
  • Override Stage: CPU-configurable pipeline-creation constant expressions declared with override.
  • Runtime Stage: Dynamic execution-time evaluations on the GPU, immutable registers (let), and mutable local thread variables (var).