nx_gsplat_res_gate.nx

nx_gsplat_res_gate.nx -- THE VIEWPORT IS A PARAMETER, AND HERE IS THE PROOF. WHY THIS GATE EXISTS. Until 2026-08-23 nx_gsplat rendered at a COMPILE-TIME 512x384 = 196,608 px. Every stage read the module consts GW/GH/GHW/GHH/GFOCAL, so the rasterizer -- and every "second renderer" the three-stage decomposition exists to enable, nx_gsplat_tile_lib included -- could only ever emit a postage stamp. A beauty-tier frame is 1920x1080 (10.55x the pixels). The ceiling was never a graphics limit; it was five constants, and the inner stages (gs_blend_rect's stride_w, gs_resolve's npx) were ALREADY viewport-agnostic. This gate holds the widening honest in BOTH directions: the historic frame must be untouched, and the wide frame must actually be wide. THE TEETH A PLAUSIBLE-BUT-WRONG IMPLEMENTATION FAILS: T4 is the ANTI-VACUITY tooth. An implementation that accepts w/h and IGNORES them still renders 512x384 and passes every "it rendered something" check. It cannot pass T4, which requires lit pixels at an index BEYOND the entire historic framebuffer -- a region that does not exist in a 512x384 render -- and a lit-count ratio no unwidened renderer can reach (its ratio is exactly 1). T1 is the NEUTRALITY control: the historic entry point and the _at entry point at the historic viewport must produce BYTE-IDENTICAL frames. Widening that disturbs the incumbent is a revert. T5/T6 are the FOV pair, asked both directions, because a derivation nobody can falsify is a guess. gs_focal_for(h) scales focal by h/GH, which holds tan(vfov/2) constant. T5 requires the derived focal to preserve the vertical angle; T6 requires the UNSCALED focal to BREAK it. A tooth that only ever sees the right answer has not tested the derivation. NOTE ON ASPECT: focal scaling preserves the VERTICAL field of view. 512x384 is 4:3 and 1920x1080 is 16:9, so the HORIZONTAL extent legitimately widens -- exactly as a real camera does when the gate is opened wider. That is why T5 measures the vertical axis: it is the axis the derivation claims. license_tier: ORIGINAL expect_exit: 0