WalkBuildingPortals transcribes the portal-only drawing-BSP walk
(BSPTREE/BSPNODE::build_draw_portals_only @0x00539860/@0x0053c100,
BSPPORTAL::portal_draw_portals_only @0x0053d870 - opposite-child-first
= far-to-near emission, IN_PLANE PORT arm emits nothing),
PView::DrawPortal @0x005a5ab0 (stab add/remove_views around the
look-in, DrawCells on pass-2 success), and the CBldPortal
PView::ConstructView overload @0x005a59a0 (side must EQUAL the authored
portal_side, clip survival, Visible destination, punch on pass 1, flood
recursion on pass 2). Punch surfaces via the pass sink for FW1
conformance; the depth-fan submission itself is FW2. Six tests: BSP
emission order both viewer sides, in-plane suppression, pass-1
punch-no-flood, pass-2 flood + DC event, sidedness rejection, unloaded
destination skip.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
