light: fixes for bjptools skip faces (which have no associated model)

include/light/light.hh

@@ -420,6 +420,9 @@ void FixupGlobalSettings(void);
 void GetFileSpace(byte **lightdata, byte **colordata, byte **deluxdata, int size);
 void GetFileSpace_PreserveOffsetInBsp(byte **lightdata, byte **colordata, byte **deluxdata, int lightofs);
 const modelinfo_t *ModelInfoForModel(const mbsp_t *bsp, int modelnum);
+/**
+ * returs nullptr for "skip" faces
+ */
 const modelinfo_t *ModelInfoForFace(const mbsp_t *bsp, int facenum);
 //bool Leaf_HasSky(const mbsp_t *bsp, const mleaf_t *leaf); //mxd. Missing definition
 int light_main(int argc, const char **argv);

light/light.cc

@@ -652,7 +652,7 @@ FindDebugFace(const mbsp_t *bsp)
     dump_facenum = facenum;
     
     const modelinfo_t *mi = ModelInfoForFace(bsp, facenum);
-    const int modelnum = (mi->model - bsp->dmodels);
+    const int modelnum = mi ? (mi->model - bsp->dmodels) : -1;
     
     const char *texname = Face_TextureName(bsp, f);
     

light/ltface.cc

@@ -639,7 +639,11 @@ PositionSamplePointOnFace(const mbsp_t *bsp,
     }
     
     const modelinfo_t *mi = ModelInfoForFace(bsp, Face_GetNum(bsp, face));
-    
+    if (mi == nullptr) {
+        // missing model ("skip" faces) don't get lighting
+        return position_t(point);
+    }
+
     // Get the point normal
     qvec3f pointNormal;
     if (phongShaded) {

light/trace_embree.cc

@@ -117,6 +117,7 @@ CreateGeometry(const mbsp_t *bsp, RTCScene scene, const std::vector<const bsp2_d
         if (face->numedges < 3)
             continue;
         
+        // NOTE: can be null for "skip" faces
         const modelinfo_t *modelinfo = ModelInfoForFace(bsp, Face_GetNum(bsp, face));
         
         for (int j = 2; j < face->numedges; j++) {
@@ -289,7 +290,12 @@ Embree_FilterFuncN(int* valid,
         
         const modelinfo_t *source_modelinfo = rsi->self;
         const modelinfo_t *hit_modelinfo = Embree_LookupModelinfo(geomID, primID);
-        Q_assert(hit_modelinfo != nullptr);
+        if (!hit_modelinfo) {
+            // we hit a "skip" face with no associated model
+            // reject hit (???)
+            valid[i] = INVALID;
+            continue;
+        }
         
         if (hit_modelinfo->shadowworldonly.boolValue()) {
             // we hit "_shadowworldonly" "1" geometry. Ignore the hit unless we are from world.