CalcPoints: Skip the trace if a PointContents says the point is already unobstructed.

Handles beveled walkways in telefragged.bsp which touch a wall along one edge, but don't split the wall.
Previously, the walkways were blocking most of the traces for the wall, messing up all of the wall sample points.

include/light/light.h

@@ -37,6 +37,8 @@
 #define TRACE_HIT_LAVA  (1 << 3)
 #define TRACE_HIT_SKY   (1 << 4)
 
+int Light_PointContents( const vec3_t point );
+
 typedef struct {
     const dplane_t *dplane;
     int side;

light/ltface.c

@@ -284,6 +284,7 @@ TexCoordToWorld(vec_t s, vec_t t, const texorg_t *texorg, vec3_t world)
 
     rhs[0] = s - texorg->texinfo->vecs[0][3];
     rhs[1] = t - texorg->texinfo->vecs[1][3];
+    // FIXME: This could be more or less than one unit in world space?
     rhs[2] = texorg->planedist + 1; /* one "unit" in front of surface */
 
     Solve3(&texorg->transform, rhs, world);
@@ -446,6 +447,35 @@ WarnBadMidpoint(const vec3_t point)
 #endif
 }
 
+/*
+ * =================
+ * NearWall
+ * 
+ * returns true if any of the 6 points up/down/left/right/front/back
+ * within 0.1 units of 'point' are in CONTENTS_SOLID
+ * =================
+ */
+bool NearWall(const vec3_t point)
+{
+    int i;
+    int insolid = 0;
+    
+    for (i = 0; i < 6; i++) {
+        vec3_t testpoint;
+        VectorCopy(point, testpoint);
+        
+        int axis = i/2;
+        bool add = i%2;
+        testpoint[axis] += (add ? 0.1 : -0.1);
+        
+        if (Light_PointContents(testpoint) == CONTENTS_SOLID) {
+            insolid++;
+        }
+    }
+    
+    return insolid > 0;
+}
+
 /*
  * =================
  * CalcPoints
@@ -486,6 +516,13 @@ CalcPoints(const dmodel_t *model, const vec3_t offset, const texorg_t *texorg, l
 
             TexCoordToWorld(us, ut, texorg, point);
             VectorAdd(point, offset, point);
+            
+            // Is the point already unbostructed? Skip doing the traceline.
+            // There could be an obstruction near the face that would block most of the traces
+            // (e.g. beveled walkways in telefragged.bsp touch a wall along one edge, but don't split the wall)
+            if (!NearWall(point))
+                continue; // all good
+            
             for (i = 0; i < 6; i++) {
                 const int flags = TRACE_HIT_SOLID;
                 tracepoint_t hit;

light/trace.c

@@ -33,6 +33,38 @@ static tnode_t *tnodes;
 static tnode_t *tnode_p;
 static const bsp2_t *bsp_static;
 
+// from hmap2
+#define PlaneDiff(point,plane) (((plane)->type < 3 ? (point)[(plane)->type] : DotProduct((point), (plane)->normal)) - (plane)->dist)
+
+/*
+==============
+Light_PointInLeaf
+ 
+from hmap2
+==============
+*/
+bsp2_dleaf_t *Light_PointInLeaf( const vec3_t point )
+{
+    int num = 0;
+    
+    while( num >= 0 )
+        num = bsp_static->dnodes[num].children[PlaneDiff(point, &bsp_static->dplanes[bsp_static->dnodes[num].planenum]) < 0];
+    
+    return bsp_static->dleafs + (-1 - num);
+}
+
+/*
+==============
+Light_PointContents
+
+from hmap2
+==============
+*/
+int Light_PointContents( const vec3_t point )
+{
+    return Light_PointInLeaf(point)->contents;
+}
+
 /*
  * ==============
  * MakeTnodes