Companion to the storage-buffer layout from step 1. Vertex shader
reads `(corner, instance_index)` per vertex, fetches the matching
`HatchInstance`, projects an AABB-quad corner; a zero `visible` flag
emits a NaN clip position so the GPU skips the fragment stage for
culled hatches without any per-frame buffer re-upload.
Fragment shader runs the same three-stage in-polygon → mode dispatch
→ pattern evaluation pipeline as `hatch.wgsl`, but with all ranges
indexed: `BoundaryBuffer[boundary_offset..offset+count]` for the
ray-cast, `FamilyBuffer[family_offset..offset+count]` for pattern
lines, `DashBuffer[dash_offset..]` for dash sequences. Phase 3.3
sub-pixel LOD substitution is preserved.
Step 3 will wire a pipeline + bind-group-layout around this and call
`upload_hatches_batched` from render.rs (the per-hatch
`upload_hatches` path stays in place for the bisect window).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
