diff --git a/src/game/bg.c b/src/game/bg.c
index ec0f7174..0702bbd1 100644
--- a/src/game/bg.c
+++ b/src/game/bg.c
@@ -636,31 +636,23 @@ Gfx *sub_GAME_7F0B3C8C(Gfx *gdl)
                 gSPMatrix(gdl++, osVirtualToPhysical((void*)get_BONDdata_field_10E0()), (G_MTX_NOPUSH | G_MTX_LOAD | G_MTX_PROJECTION));
 #ifdef PORT
                 /* TEMP D104: room render-pass geometry-visibility probe. */
-                if (getenv("GE_D104")) {
-                    static s32 d104n = 0;
-                    if (d104n < 40) {
-                        s32 *mp = (s32 *)(uintptr_t)(u32)get_BONDdata_field_10E0();
-                        s32 *pp = (s32 *)(uintptr_t)(u32)(uintptr_t)currentPlayerGetProjectionMatrix();
-                        osSyncPrintf("D104 room=%d bbox=(%d,%d)-(%d,%d) view l=%d t=%d x=%d y=%d screensize=(%d,%d)-(%d,%d)\n",
-                            dword_CODE_bss_8007FFA0[j].roomid,
-                            (s32)dword_CODE_bss_8007FFA0[j].bbox.min.x, (s32)dword_CODE_bss_8007FFA0[j].bbox.min.y,
-                            (s32)dword_CODE_bss_8007FFA0[j].bbox.max.x, (s32)dword_CODE_bss_8007FFA0[j].bbox.max.y,
-                            (s32)g_CurrentPlayer->viewleft, (s32)g_CurrentPlayer->viewtop,
-                            (s32)g_CurrentPlayer->viewx, (s32)g_CurrentPlayer->viewy,
-                            (s32)g_CurrentPlayer->screensize.min.x, (s32)g_CurrentPlayer->screensize.min.y,
-                            (s32)g_CurrentPlayer->screensize.max.x, (s32)g_CurrentPlayer->screensize.max.y);
-                        if (mp) {
-                            s32 r;
-                            for (r = 0; r < 4; r++) {
-                                f32 e0 = (f32)(s32)((mp[r*2+0] & 0xffff0000) | ((u32)mp[8+r*2+0] >> 16)) / 65536.0f;
-                                f32 e1 = (f32)(s32)((mp[r*2+0] << 16) | (mp[8+r*2+0] & 0xffff)) / 65536.0f;
-                                f32 e2 = (f32)(s32)((mp[r*2+1] & 0xffff0000) | ((u32)mp[8+r*2+1] >> 16)) / 65536.0f;
-                                f32 e3 = (f32)(s32)((mp[r*2+1] << 16) | (mp[8+r*2+1] & 0xffff)) / 65536.0f;
-                                osSyncPrintf("D104   row%d = % .4f % .4f % .4f % .4f\n", r, e0, e1, e2, e3);
-                            }
+                {
+                    static s32 d104c = 0;
+                    if (getenv("GE_D104") && (d104c++ % 600) == 0 && d104c < 12000) {
+                        s32 rr;
+                        osSyncPrintf("D104 tick=%d curRoom=%d roomsDrawn=%d budget=%d :",
+                            d104c, (s32)g_CurrentPlayer->curRoomIndex,
+                            (s32)g_BgNumberOfRoomsDrawn, (s32)g_RoomLoadBudget);
+                        for (rr = 0; rr < g_BgNumberOfRoomsDrawn && rr < 24; rr++) {
+                            s32 rid = dword_CODE_bss_8007FFA0[rr].roomid;
+                            osSyncPrintf(" r%d(ld=%d %d,%d-%d,%d)", rid,
+                                (s32)g_BgRoomInfo[rid].model_bin_loaded,
+                                (s32)dword_CODE_bss_8007FFA0[rr].bbox.min.x,
+                                (s32)dword_CODE_bss_8007FFA0[rr].bbox.min.y,
+                                (s32)dword_CODE_bss_8007FFA0[rr].bbox.max.x,
+                                (s32)dword_CODE_bss_8007FFA0[rr].bbox.max.y);
                         }
-                        osSyncPrintf("D104   f10E0=%p projm=%p\n", (void *)mp, (void *)pp);
-                        d104n++;
+                        osSyncPrintf("\n");
                     }
                 }
 #endif
@@ -1715,7 +1707,27 @@ s32 sub_GAME_7F0B5864(s32 portalnum, bbox2d *bbox)
     }
     else
     {
-        if ((bounds.max.x <= bounds.min.x) || (bounds.max.y <= bounds.min.y))
+        s32 degenerate = (bounds.max.x <= bounds.min.x) || (bounds.max.y <= bounds.min.y);
+#ifdef PORT
+        /* D106: a portal straddling the camera near-plane feeds z==0 clip
+         * points into transform3Dto2DWithZScaling, whose inv_z = -1e20 sends
+         * them to +/-1e20-scale screen coords. On N64 those bracket the view
+         * symmetrically so the box just clamps to full screen downstream;
+         * on PC the exact garbage can come back min>max on only one axis, or
+         * non-finite, slipping past the check above and culling the room the
+         * player is walking toward. Any wildly out-of-range / non-finite
+         * bound means "portal fills the view" -> full screensize. */
+        {
+            const f32 lim = 100000.0f;
+            if (!(bounds.min.x > -lim && bounds.min.x < lim) ||
+                !(bounds.min.y > -lim && bounds.min.y < lim) ||
+                !(bounds.max.x > -lim && bounds.max.x < lim) ||
+                !(bounds.max.y > -lim && bounds.max.y < lim)) {
+                degenerate = 1;
+            }
+        }
+#endif
+        if (degenerate)
         {
             bounds.min.x = g_CurrentPlayer->screensize.min.x;
             bounds.min.y = g_CurrentPlayer->screensize.min.y;