nx_gpu_geometry.nx

nx_gpu_geometry.nx -- GOAL-GPU-NATIVE rung-3: the 3D GEOMETRY STAGE (transform + project + hidden-surface). Turns flat 2D triangles into real moving 3D -- the front of the graphics pipeline, the last pure-software rung before the silicon unlock. A unit cube (8 verts, 12 triangles, 6 coloured faces) is rotated (Y then X, integer fixed-point cos/sin x256), perspective-projected to screen space, and rasterized with the rung-1 Z-BUFFER doing HIDDEN-SURFACE REMOVAL -- so only the front faces show, back faces are occluded by depth. Two frames at different angles prove the rotation is real geometry, not a static picture. KAT: the cube renders; HIDDEN-SURFACE is correct (a cube shows at most 3 faces -> <=3 face colours visible, proving back faces were depth-occluded); rotating the angle changes the projection (frame0 != frame1); frames export to BMP. All integer, fully sovereign. Feeds the GPFIFO graphics path (rung-2) as draw cmds. (cube geometry packed into one `mesh` array: verts x@0..7 y@8..15 z@16..23; tris a@24 b@36 c@48 r@60 g@72 b@84.) HONEST SCOPE: flat per-triangle depth/shading + fixed angles; smooth animation + per-pixel depth + lighting are refinements; real-time perf needs the silicon last-mile. No hw writes (Rule 26). expect_exit: 0 tier: ORIGINAL