The vertical epicyclic frequency's cross term is a√M/r^1.5 (radius to the
−1.5), following Okazaki 1987. The spec previously wrote a·Ω_φ/r, which makes
Ω_θ too large and breaks monotonic growth of precession with spin. Caught
during Task 1 implementation by the grows_with_spin test; syncing the spec
to the corrected formula that shipped in 891eadf.
Adds kerr_nodal_precession(r, chi) = Ω_φ − Ω_θ using the Okazaki (1987)
vertical epicyclic frequency:
Ω_θ² = Ω_φ² · (1 − 4a√M/r^1.5 + 3a²/r²)
χ=0 → a=0 → Ω_θ = Ω_φ → zero precession (exact Schwarzschild degeneracy).
Note on the cross term: it is a√M/r^1.5 (radius to the −1.5), NOT a·Ω_φ/r.
The latter makes Ω_θ too large and breaks the "precession grows monotonically
with spin" property — caught by the grows_with_spin test.
Three tests: vanishes at zero spin, grows monotonically with spin at fixed r,
and exceeds the weak-field 2aM/r³ approximation in the strong-field (r<6)
region. Full suite green (14 tests).
ChaCha8Rng needs both crates: rand (the core traits Rng/SeedableRng) and
rand_chacha (the ChaCha8Rng type, split out of rand since 0.9). rand was
already a transitive dep via bevy_math but not declared directly.
Pinned to 0.8/0.3 (LTS, API-stable with the Bevy 0.19 ecosystem) rather
than the newer 0.10 line, which would force a wider dep upgrade.
Spec for 5-8 planets on Kerr circular orbits with strong-field Lense-Thirring
nodal precession. Path A: CPU computes position each frame, uploads to the
existing storage buffer; shader unchanged.
Physics: closed-form Ω_φ (Bardeen 1972 eqn 2.16) and Ω_θ (Caltech Ph236
epicyclic vertical frequency), giving exact nodal precession Ω_φ - Ω_θ.
χ=0 degenerates exactly to Schwarzschild (Ω_LT = 0, Newtonian Ω_φ).
Explicitly rejects Mino-time analytic geodesics (Fujita-Hikida): circular
orbits collapse the three-frequency decomposition to Ω_φ alone, elliptic
functions have no WGSL/std backing, and it would break physics.rs's
single-testable-mirror design. Closed-form Kerr frequencies are the right
tool for circular orbits.
Orbit radius bound to k·kerr_isco(χ), so planets track the disk inner edge
as spin changes and span the strong-field region (k=2.5 → r ∈ [1.25, 7.5]).
Random initial attitudes (ChaCha8Rng + UI seed) so the three orbital planes
precess at different Ω_LT rates — the visible Kerr signature.
Decomposes Planet into OrbitParams (immutable elements) + Planet (derived
center), keeps SphereData GPU layout untouched. Adds time_scale UI knob
because Ω_LT at r=8 needs ~25 min per revolution otherwise.
The concentric banding persisted on the jets (near the base) after the
disk moiré was fixed. Root cause: sample_jets used a fixed per-step
weight (0.5) instead of a per-unit-length one, so the jet's
per-unit-length contribution was ∝ 1/step_len. RK45 packs its accepted
steps tightly near the hole (high curvature → small dt), so the jet
brightened in step-dense rings exactly where the user saw bands. This
was the inverse of the earlier `* dt` attempt (which banded because dt
varies 16×); both forms couple brightness to the integrator's step
choice rather than to the physics.
Fix: pass the step's world-space length |new_pos − prev| in from the
caller (it already has prev and new_pos) and weight the per-step
emission and alpha on it — the same step-size-decoupling technique the
disk path already uses (integrate_disk_segment's analytic seg_len). The
per-unit-length coefficient (0.1) is calibrated to keep the default
scene's jet brightness close to the old fixed-0.5 look.
cargo build --release: clean. cargo test: passing.
Two distinct sampling artifacts on the accretion disk, found with a
CPU pixel-mirror of the integrator:
1. Moiré on the disk. integrate_disk_segment placed its N sub-samples
on the deterministic (i+0.5)/N grid. That lattice aliases against
the 2-D pixel grid and the per-ray RK45 step lattice → a concentric
banding. Fix: jitter the sub-sample position within stratum i using
a hash of the pixel coordinate and the sample index. The jitter is
pixel-seeded only (no time), so the noise is spatially stable (no
per-frame flicker) and stays inside the stratum, preserving the
quadrature order. Verified by CPU mirror: banding transitions drop
sharply and the noise is unstructured.
2. Higher-order lensed-image rings read as an artifact. Rays near the
critical impact parameter wrap around the hole; each wrap crosses
the disk plane once, projecting to a ring (a physical Einstein-ring
structure, the same one Gargantua shows). The integrator renders
each wrap as a sharp discrete band, so at high `steps` the rings
look like a bug. Fix: per-pixel stochastic supersampling — fire
several jittered sub-rays per pixel and average them, which
antialiases the band edges into a smooth gradient while keeping the
underlying lensing physics.
The two fixes share a `pixel_seed` (var<private>, set from
@builtin(position)) so the jitter is deterministic per pixel.
Shader refactor: the single-ray march is extracted into march(dir);
fragment() now loops it MAX_AA_SAMPLES times (compile-time cap for
WGSL's static-loop-bound requirement, runtime count from a new
aa_samples uniform via early break — the fbm3/MAX_OCTAVES pattern).
Uniform layout: added aa_samples: u32 + two f32 pads to round the
struct to 16-byte alignment, mirrored byte-for-byte across the WGSL
struct and BlackHoleUniforms (ShaderType).
UI/params: new AaQuality enum (Off/Low/High = 1/2/4 samples) in the
Quality panel. Defaults are tiered per AGENTS.md: Off on web, Low (2×)
on desktop — the RK45 march is already ~10× Phase 1's cost, so desktop
stays at 2× with High (4×) selectable for a fully smooth look.
cargo test: 20 passed. cargo build --release: clean.
sample_jets suppresses jets for χ < 0.05 (previous commit), but the egui
panel's checkbox still flipped freely and Strength stayed editable at low
spin, so enabling jets there did nothing with no explanation — the toggle
looked broken.
Mirror the shader's gate in the UI: keep the Enabled checkbox interactive
(it expresses user intent), gray out Strength when jets won't render
(matching the existing pattern used for disk quality, Doppler, color
model, and bloom), and show a one-line hint ("Spin (χ) too low — jets
need χ ≥ 0.05.") so the no-op is self-documenting.
Three issues in sample_jets produced the reported "jet column + bright
white ring over the hole's pole" on the default scene (spin = 0,
jets_enabled = true):
1. Jets rendered at χ = 0. Relativistic jets are spin-powered
(Blandford-Znajek taps the ergosphere), which doesn't exist for a
non-rotating hole. jets_enabled was a free toggle decoupled from
spin, so the default scene showed polar columns with no physical
cause. Gate sample_jets on uniforms.spin >= 0.05.
2. Beaming saturates to white. With β=0.92 the approaching jet's
δ^3.5 reaches ~258×, blowing the blue base color past the bloom
threshold so High-level bloom (3-pyramid) collapses it to white.
Cap beaming at 8× — the approaching side is still visibly brighter,
and the base color (0.4, 0.7, 1.0) survives the HDR + bloom path.
3. dt-modulated accumulation painted ring structures. `* dt` weighted
the per-step contribution by the RK45 adaptive step size, which
varies across a 16× range (dt_min..dt_max) and between neighboring
pixels — the same class of bug the disk path already documented and
fixed in integrate_disk_segment (radial spokes). The jet has no
analytic slab to clip to, so use a fixed normalized weight (0.5);
brightness then depends only on geometry and beaming, never on dt.
Drops the now-unused dt parameter.
The renderer is GPU-bound, but Bevy's CPU path (resource management,
system scheduling, egui, wgpu command submission) still benefits from
cross-crate inlining. Cargo's default release profile skips LTO and
splits codegen across 16 units, leaving inter-crate trampolines through
Bevy/wgpu in the hot path.
- lto = "fat": whole-program cross-crate inlining.
- codegen-units = 1: best optimization (slower compiles, accepted).
- panic = "abort": smaller binary, no unwind tables.
- strip = "symbols": drop debug symbols from the shipped binary.
wasm-release inherits release then overrides opt-level to "z", so web
builds keep their size focus. Release build verified; cargo test green
(14 passed).
The web build black-screened on the first frame: the black-hole fragment
shader failed to compile in Chrome's Tint (BrowserWebGpu backend) with
"'textureSample' must only be called from uniform control flow", which
invalidated the opaque_mesh2d_pipeline and made Bevy quit after frame 1.
Desktop (naga) was unaffected because naga does not enforce this WGSL rule,
which is why the regression was web-only.
skybox_color() called textureSample on the cubemap from inside the main RK45
integration loop. That loop's control flow is non-uniform — per-pixel early
exit via `if (accum_alpha > 0.99) { break; }` and per-iteration accept/reject
— and textureSample needs screen-space derivatives (uniform across the quad)
for mip selection, so the spec forbids it there.
Switch to textureSampleLevel with an explicit LOD of 0. textureSampleLevel
does no derivative computation and is permitted in non-uniform control flow.
LOD 0 is correct for the skybox: it is sampled at full resolution with no
mip minification, so the visual result is identical to the implicit-lod path.
Diagnosis required building a JS-side probe that fetches the WGSL, mirrors
naga_oil preprocessing (resolve #{MATERIAL_BIND_GROUP}, inline VertexOutput),
then calls device.createShaderModule + getCompilationInfo to surface Tint's
structured messages — Bevy's wgpu path swallows the raw Tint error on web and
only ever surfaces the downstream "Invalid ShaderModule due to a previous
error". The probe confirmed the error site and rule; it is not committed.
Two independent sources of noise in the web console, both from the
default plugin set:
1. 'Failed to deserialize meta for asset shaders/*.wgsl'
DefaultPlugins adds AssetPlugin with meta_check = Always, so bevy
fetches <path>.meta for every shader. The shaders ship raw (no .meta
files); on the trunk dev server those requests don't return a clean
404 that bevy maps to NotFound, so bevy receives bytes and tries to
RON-deserialize them as AssetMetaMinimal, logging a SpannedError per
shader. Set meta_check = Never: it skips the meta lookup and uses the
loader's default meta — correct for processor-free raw assets.
2. 'AudioContext was not allowed to start'
The default AudioPlugin opens a WebAudio sink at startup; browsers
block that until a user gesture and log it as a JS error. This app
has no audio, so disable AudioPlugin entirely — removes the noise and
shrinks the wasm binary.
Bevy's HttpWasmAssetReader fetches asset paths over HTTP at runtime,
requesting 'assets/shaders/*.wgsl' (matching AssetPlugin's default
file_path of "assets"). Trunk only emits what index.html references,
so without an explicit copy-dir link the shaders were absent from dist/
and every material hit a 404 → grey screen.
Add the copy-dir link so trunk mirrors assets/ into dist/.
The previous per-step accumulator weighted density by `step_len` — the
RK45 step length. That step size is spatially adaptive (small near the
hole where curvature is high, large in flat regions) and varies between
neighbouring pixels, so `density * step_len` injected a per-pixel
brightness modulation along the radial direction: radial spokes,
densest at the inner disk where steps are smallest.
Fix: a new integrate_disk_segment clips each step's segment to the disk
slab analytically and weights samples by `seg_len` — the world-space
length of the ray-slab intersection, which depends only on the ray's
incidence angle and the local slab height H, never on the RK45 step
size. Slab height uses the step-midpoint r (H/R ratio; r varies <5%
across one step).
Within the clipped segment, N=4 uniform samples replace the single
midpoint. A single sample under-integrates the Gaussian vertical decay
and leaves the disk translucent; four samples resolve the density
profile across the slab thickness while keeping the cost bounded (4 ×
2-octave fbm per in-slab step).
This recovers the pre-regression slab-clipping geometry but with
segment-multi-sampling instead of one midpoint — the slab clip removes
the step-size coupling (spokes), the multi-sample restores the
integration depth (opacity).
Off-tier (disk_quality == 0, flat path) is untouched: it samples a
zero-thickness midplane with no slab, so step-size weighting never
applied there.
Defaults retuned to match the Interstellar look now that the density
model drives appearance:
- disk_outer 15 → 25: Gargantua-like extent.
- disk_half_thickness semantics → H/R ratio, default 0.15 (was an
absolute 0.3/0.2 world-space band). Standard thin-disk scale height.
- disk_color_mode default → Blackbody (was Gradient): the Novikov-Thorne
radial temperature gradient × Kerr Doppler gives the smooth white-hot
inner → deep-orange outer look the new density model is built around.
- disk_temp 10000 → 6500 K: tuned so the NT profile yields warm-white
inner fading to deep orange at the edge.
- density_strength 1.0 → 1.2: the new model has no floor and decays to 0
at the edges, so a slightly higher multiplier keeps the bulk opaque
after per-step integration.
UI: "Half thickness" → "Thickness (H/R)" with a 0.02..=0.3 range
(thin-disk regime); "Outer radius" range widened to 6..=50.
BlackHoleUniforms::Default (material.rs) mirrors the same values so the
GPU default matches params.rs before the first mirror_params tick. Field
order/types/layout unchanged; no uniform-struct migration needed.
The volumetric disk rendered translucent and jelly-like. Three causes,
all fixed:
1. Density floor 0.55 (disk_color_volumetric): noise valleys stayed
semi-transparent no matter the integration → jelly. Replaced with a
physical density field: radial smoothstep falloff × Gaussian vertical
decay × weak ±25% low-frequency turbulence. Density now reaches 0 at
the edges and peak at the midplane, so per-step integration builds a
solid disk instead of a uniform glow.
2. Single midpoint sample (main loop): the old design clipped the ray
segment to the slab and sampled density once at the midpoint, then
weighted by segment length. Under-integration → see-through. Switched
to per-step accumulation: every accepted step whose endpoint is inside
the slab samples density once × geometric step length — the standard
front-to-back volumetric composite, matching the others/ reference
(fragment.glsl.ts sample_accretion_disk).
3. Absolute slab thickness 0.3: vanishingly thin at large radius → even
less integration. disk_half_thickness is now an H/R RATIO; the slab
scales as H = r·disk_half_thickness (a thin disk's geometry), so a ray
through large r traverses a proportionally thicker region.
The ridged-filament brightness driver and log-spiral arm modulation are
removed — they produced the noisy, striated look. The radial temperature
gradient inside disk_emission (Novikov-Thorne × Kerr Doppler) now
dominates, giving a smooth disk like DNEG's Gargantua render. Noise
functions (fbm3/ridged_fbm/value_noise3) are retained: jets and the flat
(Off-tier) path still use them.
disk_color_flat (Off tier) drops its fixed 0.85 alpha for the same radial
smoothstep, so edges feather consistently across all quality tiers.
- params.rs: collapse `if cfg!(wasm) { false } else { true }` for
star_aa into `!cfg!(wasm)` (clippy::needless_bool).
- render/plugin.rs: `resize_offscreen` is a Bevy system whose argument
count is fixed by its SystemParam set; allow clippy::too_many_arguments
alongside the existing type_complexity allow on the same function.
The control panel grew past one screen after the disk/jet additions
(Color model, Temperature, Jets section). egui::Window without a height
constraint just clips overflowing content. Give it a default width/height,
enable resizing, and wrap the body in ScrollArea::vertical so all sections
remain reachable.
Bring three accretion-disk strengths from others/blackhole-simulation into
the WGSL renderer, behind opt-in controls. The physics.rs CPU mirror is
untouched — these are all color/shading functions, outside the deriv/rk45/
integration-loop lockstep surface.
Color model (DiskColorMode uniform, default Gradient to preserve the prior
look):
- Gradient (mode 0): existing white-hot → orange ramp + Newtonian
apply_doppler, unchanged.
- Blackbody (mode 1): Novikov-Thorne radial temperature profile
(isco_r^0.75 · (1−√isco_r)^0.25) shifted by the Kerr equatorial
4-velocity Doppler factor δ, fed through a Tanner-Helland blackbody
color function, times δ^3.5 beaming. The approaching side therefore
turns hotter/bluer and the receding side cooler/redder — the physical
signature the gradient mode lacks. kerr_doppler() solves g_μν u^μ u^ν=-1
for circular orbits exactly; the max(0.01,…) floor guards pow-of-negative
NaN. A unified disk_emission() now assembles color for both the flat and
volumetric paths, replacing two duplicated tcol/falloff/doppler chains.
Relativistic jets (jets_enabled, default on): bipolar cones along the spin
axis with 0.92c outflow beaming (δ^3.5, no floor needed — β fixed keeps the
denominator positive), Gaussian radial falloff, exponential length decay,
and outward-flowing value-noise turbulence. Front-to-back composited into
the same accumulators as the disk. Ported to ptr<function,…> accumulators
(WGSL has no inout) and the existing value_noise3.
UI: Color model dropdown + temperature slider under Accretion Disk; new
Jets section with enable + strength. Four uniform fields added as one
16-byte row, Rust/WGSL order kept identical.
Verified: cargo build --release, cargo test (17 tests, mirror untouched),
naga WGSL validation.
Set the OrbitCamera default to the framing the UI screenshot shows:
yaw -1.065, pitch -0.335, distance 30, fov 1.0 (the latter two were
already the defaults).
The old default (yaw 0, pitch +0.7) was a 3/4 view from above the disk
plane. The new pitch sits the eye just below the disk plane, so the
gravitationally lensed far side of the disk arcs over the top of the
shadow — the iconic Interstellar framing. yaw -1.065 (~-61°) picks a
viewing azimuth that keeps the lensed arc and photon ring balanced in
frame.
Root cause of the radial spokes (the "zebra stripe" artifact): the
volumetric integration used TWO overlapping sampling paths per RK45 step
with inconsistent angle-dependent weights:
(A) in-slab step: accum += density * step_len
where step_len = full RK45 step (may extend far outside the slab)
(B) edge-capture: accum += density * thickness_proj
where thickness_proj = half_thickness / |dir.y|
At a straddling step BOTH fired. step_len (RK45 adaptive) and thickness_proj
vary with the ray's bending geometry differently, so their sum modulated
brightness by angle → radial spokes whose count/position shifted with the
camera angle. This was confirmed decisively: setting the texture to a
completely uniform constant (no noise, no arms) STILL produced spokes,
proving the texture was innocent and the integration was the source.
Fix: replace the two-path design with a single unified path. Clip each
RK45 step's segment to the slab |y|<=half_thickness (parametric clip in
t-space), sample once at the clipped segment midpoint, accumulate × the
in-slab segment length only. This gives consistent, geometry-correct
weights with no double-counting. Verified: uniform-constant texture now
renders a clean smooth ring (no spokes); full texture restores turbulent
filaments without spokes.
Also reverts the temporary uniform-constant debug texture to the full
polar-sampled ridged+density+arms function.
Root cause of the "zebra stripe" / radial spoke artifact: disk_color_volumetric
sampled noise using the raw Cartesian pos (x,y,z). On a disk, changing the
radius r moves x/z a lot (high-frequency oscillation → stripes), while a full
angular sweep revisits correlated lattice points (weak variation), so the
stripes elongate along radius into spokes. Verified numerically: the radial
sample line oscillated filament in [0.05, 0.77] while the angular line was
symmetric (phi=0 and phi=pi identical at 0.2475).
Fix: sample noise in polar space sp = (r/inner, phi*2.5 + rot, h/half_thickness).
This decouples radial and angular axes so turbulence flows tangentially — the
physically correct pattern for a rotating fluid. Post-fix radial/angular
variance ratio is 0.50 (radial smoother than angular), eliminating the spoke
bias.
Two secondary fixes in the same function:
- Density: replaced the hard smoothstep(0.3,0.7) cut (which made the slab
patchy and over-transparent) with a soft 0.35+0.65*noise ramp.
- Brightness: raised the floor to 0.5+filament (was filament alone) so the
disk reads as luminous plasma instead of dim brown.
- Guarded log(r) with max(r,0.1) for robustness near the inner edge.
This branch is the first to call fbm3 with runtime-variable octave counts
(previously only compile-time constants 3u/4u). The spec's WebGPU safety
mitigation (fixed upper bound + early break) was applied to ridged_fbm
but missed on fbm3. Ports the same pattern so older WebGPU drivers don't
miscompile the dynamic loop bound.
Live-tunable volumetric disk params. Quality ComboBox (Off/Low/Medium/
High) mirrors the Bloom quality pattern; the 8 sliders disable when Off.
Off reverts to the flat disk for perf escape + visual A/B.
Restructures the disk block in the main loop:
- Off tier: flat disk_color_flat single midplane sample (old behavior).
- Volumetric tiers: (A) in-slab per-step sampling accumulates emission ×
arc length, reusing the RK45 adaptive step density; (B) midplane edge-
capture weights one at-plane sample by slab depth along the ray.
Removes the Task-5 disk_color shim. physics.rs untouched; cargo test green.
Three multiplying signal layers: ridged_fbm filaments for brightness,
smoothstep-gated FBM for density clumping, logarithmic-spiral arm
modulation riding the Keplerian shear. Octave triplet selected from
disk_quality tier. Returns DiskSample; inert until Task 7 wires it in.
Splits disk_color into shared helpers (temperature_color, radial_falloff,
apply_doppler, r_of) reused by both the flat and volumetric paths.
disk_color_flat returns a DiskSample with the old fixed 0.85 alpha,
preserving the exact pre-volumetric appearance behind the Off tier. A
temporary disk_color shim keeps the main-loop call site compiling until
Task 7 restructures it.
Ridged noise (1 - |2n-1|, raised to sharpness) produces the sharp bright
filaments the spec calls for, replacing the smooth FBM blobs. Fixed
MAX_OCTAVES=6 with early break — conservative form for runtime-chosen
octave counts on older WebGPU drivers. Inert; no caller yet.
Extends mirror_params with the 9 new field assignments. DiskQuality enum
gains an as_u32() accessor for the WGSL tier selector. GPU now receives
live values; shader does not consume them yet.
Data layer for the volumetric disk. DiskQuality gates octave counts
(Off/Low/Medium/High); Off is a full revert to the flat disk. Eight new
tunable f32 fields for thickness, filament, density, and spiral-arm
control. Web defaults to Low tier + 0.2 half-thickness; desktop to
High + 0.3. Nothing reads these yet.
Design for replacing the smooth zero-thickness disk with a Gargantua-style
volumetric gas disk. Supersedes the Phase 3 non-goal "disk stays a zero-
thickness plane" - user feedback identified zero thickness as a root cause
of the disk looking too smooth.
Key decisions captured:
- Approach A volumetric integration: in-slab sampling reuses the existing
RK45 adaptive step (dense where light bends, sparse where straight),
no separate ray-march. Midplane edge-capture retained for straddling steps.
- Ridged multifractal noise (ridge^2) for sharp bright filaments, replacing
the smooth FBM blobs that produce the current mushy texture.
- Separate density field (smoothstep-gated FBM) for gas clumping, plus a
logarithmic-spiral arm modulation riding the Keplerian shear.
- DiskQuality tier enum (Off/Low/Medium/High) gates octave counts; Off is
a full revert to the flat disk as perf escape hatch + visual A/B.
- physics.rs untouched: volumetric integration is render-sampling layer,
never enters the geodesic solver; existing tests stay green.
After the round-star fix, toggling "Anti-aliased stars" made stars look
bigger and more numerous instead of just smoother. The AA path differed
from the hard-edge path in three ways that each inflated the footprint:
- radius: AA used 0.25 + b*0.4 (up to 0.65); hard path used fixed 0.5
- gain: AA used 4.0; hard path used 3.0 (+33% peak brightness)
- falloff: AA Gaussian decayed slowly (36.8% at one radius, never 0);
hard path smoothstep hit 0 at the radius
The slow Gaussian tail was the main offender: it kept dim stars lit far
past the hard path's cutoff, lifting many sub-threshold stars above the
visibility floor — the apparent "more stars".
Balance the two paths so the toggle is purely an edge-softness control:
- both use radius = 0.25 + b*0.4 (same size, brightness-driven)
- both use gain 3.0 (same peak brightness)
- AA steepens the Gaussian to exp(-4.6*d²/r²) so it converges to ~1%
near the same radius where smoothstep cuts to 0 — matched footprint,
soft vs hard edge.
Peak brightness is now identical across the toggle; effective lit area
differs by <30% (the Gaussian is a cone, smoothstep a flatter dome) and
the visibility radius matches, so dim stars no longer pop in and out as
AA is toggled.
Validated: naga type-checks; app runs 20s on Metal (M4) with no shader
errors; cargo test (14 physics tests) passes.
Background stars looked square even with anti-aliasing on, and toggling
AA just made them bigger rather than round. Two compounding causes, both
in star_color():
1. Square shape: the fast path measured cell distance with
max(f.x, max(f.y, f.z)) — Chebyshev distance, which draws an
axis-aligned cube, not a sphere. The visible star was literally a
faded cube face.
2. AA "just makes it bigger": the Gaussian AA path used Euclidean
distance, but only inside ONE cell. hash13(cell) returns a different
value across a cell boundary, so a star's radial falloff could never
reach zero — it was hard-clipped at the cell edge. The star's outline
was therefore the cell's bounding box regardless of the radius
parameter; bumping the gain/radius just filled more of that box.
Fix: scan the 3x3x3 neighborhood of cells so a star whose center lies in
an adjacent cell still contributes across the whole cell it lives in,
and take the brightest contributor. Distance is Euclidean in both paths,
so both are now genuinely round. star_aa selects soft Gaussian glow (on)
vs. a tight smoothstep disk (off) — a real shape choice instead of
square-vs-clipped-square.
Validated: naga type-checks the preprocessed shader; app runs 20s on
Metal (Apple M4) with no shader/compile/validation errors; cargo test
(14 physics tests) passes.
Two runtime validation errors crashed the app on startup:
1. BrightPassMaterial used #[uniform(0)] threshold: f32 (bare f32 = 4-byte
binding), but the WGSL BrightPassUniform struct is 16 bytes (threshold +
3 pads). The pipeline-layout mismatch ("Buffer structure size 16...
greater than min_binding_size, which is 4") killed the opaque_mesh2d
pipeline. Fix: wrap threshold in a BrightPassUniform struct matching the
WGSL layout, same pattern as BlurUniform/CompositeUniform.
2. bevy_egui 0.41's auto-context assigns PrimaryEguiContext to the FIRST
Added<Camera> — with the 7-camera bloom pipeline, that's the offscreen
camera (renders to Rgba16Float Image). egui's pipeline expects the
window's Rgba8UnormSrgb surface → format mismatch crash. Fix: disable
auto_create_primary_context (PreStartup system) and explicitly tag the
composite (window) camera with PrimaryEguiContext.
Both fixes verified: the app now runs without validation errors for 8+
seconds. Physics tests (20/20) unaffected.
Adds a dedicated Quality collapsible section: bloom quality dropdown
(Off/Low/Medium/High), bloom threshold/strength, exposure, resolution
scale, star AA toggle. Changing bloom quality at runtime triggers a
pipeline rebuild (despawn bloom entities + respawn via spawn_bloom_pipeline
helper). MSAA honestly labeled as decorative.
Note: the rebuild currently re-spawns the full 3-level pyramid whenever
bloom is enabled (Off vs On). Partial pyramids for Low/Medium are a
future enhancement.
BloomQuality { Off, Low, Medium, High } controls pyramid depth (0-3).
Web defaults to Low (1 level, minimal float textures), desktop to High
(3 levels, full cinematic). Off skips all bloom passes and composites
scene-only with ACES — the fallback path for WebGPU browsers without
float-filterable support. The composite samples a 1x1 black texture
when bloom is off.
Note: this task gates Off vs full-On (3-level pyramid always runs when
enabled). Partial pyramid for Low/Medium is deferred to the runtime
rebuild in Task 8.
Adds CompositeMaterial + composite.wgsl: combines the HDR scene with the
bloom pyramid output, applies ACES (Narkowicz) tone mapping, and writes
LDR to the window. Removes UpscaleMaterial + upscale.wgsl.
mirror_params now updates composite (bloom_strength, exposure) and
brightpass (threshold) uniforms each frame. resize_offscreen rebuilds
the full bloom pyramid targets on window resize.
Adds BlurMaterial + blur.wgsl with a 13-tap weighted Gaussian kernel
(var<private> arrays — naga rejects dynamic indexing of const arrays),
run in downsample then upsample passes. For the 3-level pyramid:
bloom_0 (half, from brightpass) → bloom_1 (quarter) → bloom_2 (eighth),
then upsample to bloom_final (half). Camera orders -18/-17/-16/-15.
The bloom output is not yet composited (Task 6); this commit only wires
the passes and confirms they run in sequence without crashing.
