The mirror compiles under using static CultMath.math, so it proves composition,
not intrinsic rules; HlslSemanticsTests alone pins those. design.md also states
where FMin/FMax/Saturate turn NaN or infinity into numbers and tells callers to
check isnan first.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
SequenceEqual on floats treats -0 as 0. The mirror test now compares
SingleToInt32Bits, with any NaN equal to any NaN. Its summary and
design.md now say the test proves CultMath.hlsl's text computes the same
float32 results as C# math on the CPU, not that a GPU agrees: driver sin
precision alone makes cultmath_hash and value noise differ on hardware.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
dxc lowers float min/max/clamp to dx.op FMin/FMax (36/35) and saturate to
dx.op Saturate (7). DXIL.rst defines them: FMin(a, b) is a < b ? a : b,
FMax(a, b) is a >= b ? a : b, a NaN operand returns the other, and
Saturate is FMin(1, FMax(0, x)). C# used MathF.Min/Max, which pass NaN
through and order signed zeros, so saturate(NaN) was NaN instead of 0.
Every float overload now follows the spec, normalize uses the same max as
its mirror, and the mirror's saturate spells Saturate's operand order
(which maps -0 to +0, where clamp(x, 0, 1) keeps -0). Non-NaN results
change only in the sign of a zero. design.md records the rules and that
dxc marks float math fast, so GPU NaN results are not guaranteed.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The operator kept the [UnscopedRef] ref this[int] row indexer as is. design.md
and the float2x2/float3x3 indexers now say where m[r][c] = v lands: locals,
array elements, class fields, and ref locals keep the write; a readonly field,
in parameter, property (auto-properties too), or static readonly identity
takes a defensive copy, so the write compiles and is lost. Fix: copy to a
local, write, assign back. Verified by compiling and running each case with
Roslyn against CultMath (no diagnostics; writes land 5, lost 0).
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
dxc 1.9.0.5402 (dxc_2026_07_29, lib_6_3, -HV 2021, -Od) lowers step(e, x) to
fcmp olt x, e; select 0 : 1, so NaN on either side gives 1. The previous
x >= e ? 1 : 0 rule came from prose, not the compiler. math.step and
cultmath_step now use x < e ? 0 : 1 for every overload; the mirror's
cultmath_step compiles to the same fcmp/select as the intrinsic. Unity shader
copy synced; DLL rebuilt and byte-checked by build-unity-package.ps1.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
design.md states the generated swizzle and mixed-constructor surface, writable
matrix rows, HLSL intrinsic types and NaN behavior, the deferred matrix items
(float4x4, transpose, determinant, _11 names), the exact HLSL-to-C#
transformations the compatibility test applies, and the dxc check.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The design doc now names HLSL as the parity target: HLSL-shaped math
compiles as C# under using static CultMath.math, components and swizzles are
writable, comparisons are component-wise, matrices are row-major through mul,
and select uses HLSL's argument order. "Prefer small immutable value types"
becomes plain mutable value types. CultMath keeps its own decisions where
HLSL is silent (safe normalize, float hash, its own Random), and the core
assembly stays engine-free.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
