The point-in-polygon test in both hatch shaders walked edges
(v0,v1)…(vn-2,vn-1) but never the closing edge vn-1→v0, so an unclosed
boundary miscounted crossings and the fill bled outside the shape. SOLID
entities hit this — their four corners are not repeated — making color-wheel
fills spike past their bounds. Close each sub-loop (at NaN separators and at
the end); already-closed loops get a degenerate closing edge that crosses
nothing, so they're unaffected. (#140)
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>