Hatch fills drew the full per-family pattern loop every frame regardless
of zoom. Two LOD tiers, neither of which existed:
* **Shader-side solid substitute.** When the densest line family's
spacing × scale projects to less than 2 px, individual lines blur
into a solid color and the per-fragment family loop is wasted ALU
(and produces moiré). Pass `world_per_pixel` through Uniforms; the
hatch fragment shader now returns `h.color` directly in that case.
* **CPU-side sub-pixel skip.** When the entire hatch AABB projects
to less than 2 px, drop the draw call. Adds `world_aabb` to
HatchGpu plus a per-frame `compute_hatch_lod` pass (mirrors the
existing scissor pass) and `hatch_skip_flags`. The render pass
skips flagged hatches.
Factored a shared `aabb_below_pixel` helper for future LOD callers.
The Uniforms layout is unchanged in size (96 B) — the trailing
`_pad: vec2<f32>` becomes `world_per_pixel: f32, _pad: f32`, so wgsl
modules that don't read the new field keep working with their old
`_pad: vec2<f32>` declarations.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
