nx_raster_sw.nx

nx_raster_sw.nx -- bits-up integer software triangle rasterizer. LINEAGE (per [[feedback-no-tool-proliferation-consolidate-or-justify]] cardinal landed 2026-05-20): Distinct from [[nx_raster.nx]] because: nx_raster.nx ships Bresenham lines + Pineda triangles + barycentric-shaded triangles on the *Image abstraction; this file ships Pineda strict-interior coverage on the *i64 framebuffer directly, AND exposes the edge function + signed-area helpers as public APIs for downstream composition. Distinct from [[nx_raster_triangle.nx]] because: nx_raster_triangle.nx adds a Z-buffer for 3D occlusion; this file is the 2D strict-interior coverage path used by the perceptual-render demos that don't need depth. The two compose: nx_raster_triangle.nx CALLS the edge function exported here in its Pineda inner loop. HONEST PROLIFERATION NOTE: the substrate has three rasterizer primitives by 2026-05-20. Future raster work MUST extend one of these three, not ship a fourth. When the substrate hits 4 rasterizers, consolidate per the cardinal. G1 first stone of NISHI_GRAPHICS_ROADMAP.md. Pineda 1988 edge- function method, absorbed clean-room from the ACM SIGGRAPH paper. Pure integer i64 math; no libm; no float; no SIMD; no GPU. Composes: [[NISHI_GRAPHICS_ROADMAP]] G1 existing nx_framebuffer.nx (this rasterizer uses nx_fb_set as its pixel write primitive; preserves additively per Cardinal 13) [[feedback-bits-up-exceed-never-match]] (no Cairo, no Skia, no Mesa, no AGG; integer-only Pineda) [[feedback-no-false-ok-substrate-honesty-audit]] (degenerate + CW triangles return 0 pixels deterministically; KAT verifies known triangle -> known pixel count) API: nx_raster_signed_area_2x(x0,y0,x1,y1,x2,y2) -> i64 Returns twice the signed area. Positive => front-facing (drawable). Zero => degenerate (collinear). Negative => back-facing (culled).