trace: steps per pixel and pass ms at three fixed camera poses, PREPASS=0,1 arms.
diff: one frozen frame with and without the prepass, against a 512-step render.
bundle.cjs demo: full-window page with a prepass switch and the readout.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Sky rays were ~90% of pass 1 (noSkyMarch variant: 292 -> 26 ms, SwiftShader 960x540 L0).
terrainDistance now returns early where the plateau mask is 0 (height exactly 0), skipping
fbm and Phacelle there: pass 1 292 -> 159 ms, same step values. skyColor keeps one sun term
(the wide glow is gone; screenshots differ by that and by TAA/time, not compared pixelwise).
Harness: noSkyMarch variant, ONLY=<names> selects variants.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Pass 1 sphere-traces CultMath noise terrain (fbm plus Phacelle erosion) and the
world tree with a conservative Lipschitz step, writing colour and depth. Pass 2
marches fog and clouds only up to that depth at low resolution with TAA. The
camera pulls back from the tree on login. Vendors CultLib's generated GLSL
(658c09e). The Phacelle gradient bound is an empirical probe, not a proof.
Headless harness compiles, renders and times it; nothing run on a GPU.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
