The disk's noise was two sin() terms (phi*8, phi*23) producing geometric
bands. Replace with domain-warped FBM: a 3-octave value-noise field warps
the sampling coordinate of a 4-octave FBM, giving the feathered/smoky gas
texture of the Gargantua reference. The Keplerian shear (rot ∝ 1/r^1.5)
is retained as the flow time term so inner radii rotate faster.
The app showed only the camera clear color (grey srgb 43,44,47) — the
fullscreen quad's fragment shader produced no output. Two issues; the
second was the real blocker.
1. render/material.rs: skybox.wgsl declared binding 1 as texture_cube<f32>
but the material's #[texture(1)] defaulted to D2. The mismatched
bind-group layout vs. shader caused the pipeline to fail to specialize.
Fix: dimension = "cube" on the texture attribute so the layout matches.
2. SHADER COMPOSITION (the actual blocker): the shader was split across
naga_oil modules (ray_gen, geodesic, stars, disk, planets, grid, skybox)
pulled in via #import singularity::... This compiled and validated with
zero errors, but at runtime calling ANY cross-module-imported function
made the fragment output nothing (only the clear color showed). Local
functions were fine. Confirmed by bisecting a minimal repro with the
user watching the screen: local fn -> renders; imported fn (even pure
math) -> grey.
Rather than chase the naga_oil 0.22 / Bevy 0.19 composition bug, inline
every function into black_hole.wgsl and drop the #import singularity::*
lines. The 7 standalone module files are removed. Rendering now works.
Also fixes scene/planets.rs: upload_planets was allocating a fresh
ShaderBuffer (new handle) every frame, which re-triggered the
AsBindGroup RetryNextUpdate that the previous commit's startup pre-fill
was meant to eliminate. Now mutates the existing buffer asset in place
via set_data, keeping the handle stable.
The committed Phase 1 code rendered a black screen due to three
independent bugs, fixed here:
- black_hole.wgsl: dt was sized as |eye|/steps, so the full integration
only traveled |eye| units total — rays never reached capture or escape
and every pixel fell through to accum=black. Now dt covers
eye_dist + escape_r across the configured step count, and the escape
test uses the dynamic escape_r instead of a hardcoded 1000.0.
- render/plugin.rs: the planets binding was Handle::default(), causing
AsBindGroup to return RetryNextUpdate every frame and silently skip
the fullscreen quad's draw. Pre-fill a MAX_PLANETS-sized zeroed
ShaderBuffer at startup so the binding resolves immediately.
- render/plugin.rs: scale the fullscreen quad by half the window size
to match Camera2d's default WindowSize projection (1 unit = 1 px);
the old aspect-based scaling letterboxed the image.
- render/plugin.rs: add nudge_camera to work around Bevy 0.19 #24448,
where a static camera stops rendering after the first frame.
- planets.wgsl: rotate world-space planet centers into disk-local space
before the ray-sphere test (ray and centers were in different spaces).
The whole-file #import "file.wgsl" form (without ::) does not reliably
bring functions into scope in naga_oil/Bevy 0.19 — the renderer was
failing at runtime with 'no definition in scope for identifier:
ray_direction' (and rot_x, deriv, etc.), producing a blank screen despite
'cargo build' passing (shaders aren't compile-checked at build time).
Fix: add #define_import_path to each module file and import symbols
explicitly via namespace::name (the canonical Bevy pattern from the
shader_material_2d example). Verified the full shader pipeline compiles
and runs at runtime with zero WGSL errors.
This was a pre-existing bug masked by incomplete runtime verification in
earlier tasks; it is NOT specific to Task 15's grid work. All earlier
visual features (shadow, Doppler disk, Einstein halo, stars, planets,
grid) now actually render.
Add planets as ray-traced spheres inside the RK4 geodesic loop. A new
planets.wgsl shader tests each integrator segment against a storage
buffer of SphereData (center/radius/color/emissive) and composites hits
front-to-back alongside the accretion disk. Lambert shading with a fixed
light direction; emissive flag bypasses shading.
- assets/shaders/planets.wgsl: segment-sphere intersection + shading
- src/scene/: Planet component, upload_planets system, default planet
- black_hole.wgsl: wire planet_hit into the compositing loop
- geodesic_schwarzschild.wgsl: replace tuple return with Deriv struct
