A user-defined hatch (angle + spacing + optional cross) carries the
placeholder pattern name "_USER", which isn't in the predefined catalog,
so it fell to a fallback that forced every one to flat horizontal lines
at the wrong spacing — ignoring the angle, the spacing and the double
flag.
Build base line families (angle 0, plus 90 when `is_double`) with unit
perpendicular spacing and let the HatchModel's existing angle_offset
(= pattern_angle) and scale (= pattern_scale) rotate and space them, the
same way predefined .PAT patterns are applied — so the angle/scale is
applied once, not doubled. Verified against the sample (0°/30°/90°-cross/
315°-cross at spacing 5/10).
Closes#278
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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