Volumetric self-screening constants (VOLUMETRIC_BLENDING_SPEC.md §3).
S(τ) = (1 − e^(−τ))/τ is evaluated as the guarded quotient above
VOLUMETRIC_SERIES_TAU_THRESHOLD and as the Maclaurin
polynomial S(τ) ≈ 1 − C1·τ + C2·τ² below it (the naive quotient
loses ~7 digits to cancellation as τ → 0; the series' relative error
is < 1e-10 at the cutoff). Single TS source of truth — the ALPHA_CLAMP
pattern — so the GLSL templates, the TSL graphs, and the
volumetric-math unit test all derive from identical numbers.
Volumetric self-screening constants (VOLUMETRIC_BLENDING_SPEC.md §3). S(τ) = (1 − e^(−τ))/τ is evaluated as the guarded quotient above VOLUMETRIC_SERIES_TAU_THRESHOLD and as the Maclaurin polynomial S(τ) ≈ 1 − C1·τ + C2·τ² below it (the naive quotient loses ~7 digits to cancellation as τ → 0; the series' relative error is < 1e-10 at the cutoff). Single TS source of truth — the ALPHA_CLAMP pattern — so the GLSL templates, the TSL graphs, and the volumetric-math unit test all derive from identical numbers.