Four ridge layers generated once on the CPU from CultMath value-noise fbm, each painted
once to an integer-size 2D canvas over a baked sky; CSS translate3d drift only. Pauses
hidden / reduced motion; falls back to a still image if rAF p95 > 33 ms over 2 s;
?probe=1 shows median/p95. Same createScene contract, tier flag still defaults off.
Ray-march scene stays behind backgroundScene.style = 'raymarch'.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Phone Chrome without EXT_color_buffer_float returned null with one message. Rendering to
RGBA16F only needs EXT_color_buffer_half_float, and every other target is already a half, so
only the prepass start (RGBA32F) needed a fallback. In half mode the prepass writes
t*(1-2^-10) - 2^-15, which stays below t after the half rounds to nearest, so pass 1 still
starts at or before the true distance. W_FAR stays exact. onUnavailable names no-webgl2 vs
neither float extension; Scene.startFormat and options.halfStart (force, for tests and the
harness). The standalone page shows the reason, renderer, vendor, UA and extension list.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
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>
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>
