xfy ee15ddecb7 fix: make the renderer actually draw (step size, storage buffer, quad fit)
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).
2026-07-13 11:47:31 +08:00
..