improve area calculation by a shift width to simulate fragments

diff --git a/tools/quake3/q3map2/surface_meta.c b/tools/quake3/q3map2/surface_meta.c
index f61c6b73531e47b291dd23e63dd0b0e1fd9d64e4..8b68ce77c7dc2d488112fe387bda1b473d76b7aa 100644 (file)
--- a/tools/quake3/q3map2/surface_meta.c
+++ b/tools/quake3/q3map2/surface_meta.c
@@ -421,10 +421,43 @@ int MaxAreaIndexes(bspDrawVert_t *vert, int cnt, int *indexes)
        double A, bestA = -1, V, bestV = -1;
        vec3_t ab, ac, bc, cross;
        bspDrawVert_t *buf;
+       double shiftWidth;
 
        if(cnt < 3)
                return 0;
 
+       /* calculate total area */
+       A = 0;
+       for(i = 1; i+1 < cnt; ++i)
+       {
+               VectorSubtract(vert[i].xyz, vert[0].xyz, ab);
+               VectorSubtract(vert[i+1].xyz, vert[0].xyz, ac);
+               CrossProduct(ab, ac, cross);
+               A += VectorLength(cross);
+       }
+       V = 0;
+       for(i = 0; i < cnt; ++i)
+       {
+               VectorSubtract(vert[(i+1)%cnt].xyz, vert[i].xyz, ab);
+               V += VectorLength(ab);
+       }
+
+       /* calculate shift width from the area sensibly, assuming the polygon
+        * fits about 25% of the screen in both dimensions
+        * we assume 1280x1024
+        * 1 pixel is then about sqrt(A) / (0.25 * screenwidth)
+        * 8 pixels are then about sqrt(A) /  (0.25 * 1280) * 8
+        * 8 pixels are then about sqrt(A) * 0.025
+        * */
+       shiftWidth = sqrt(A) * 0.0125;
+       /*     3->1 6->2 12->3 ... */
+       if(A - ceil(log(cnt/1.5) / log(2)) * V * shiftWidth * 2 < 0)
+       {
+               /* printf("Small triangle detected (area %f, circumference %f), adjusting shiftWidth from %f to ", A, V, shiftWidth); */
+               shiftWidth = A / (ceil(log(cnt/1.5) / log(2)) * V * 2);
+               /* printf("%f\n", shiftWidth); */
+       }
+
        /* find the triangle with highest area */
        for(r = 0; r+2 < cnt; ++r)
        for(s = r+1; s+1 < cnt; ++s)
@@ -436,9 +469,9 @@ int MaxAreaIndexes(bspDrawVert_t *vert, int cnt, int *indexes)
                CrossProduct(ab, ac, cross);
                A = VectorLength(cross);
 
-               V = A - (VectorLength(ab) - VectorLength(ac) - VectorLength(bc)) * 0.2;
-               /* value = A - circumference * 0.2, i.e. we back out by 0.2 units from each side, to prevent too acute triangles */
-               /* this kind of simulates "number of 0.2x0.2 fragments in the triangle not touched by an edge" */
+               V = A - (VectorLength(ab) - VectorLength(ac) - VectorLength(bc)) * shiftWidth;
+               /* value = A - circumference * shiftWidth, i.e. we back out by shiftWidth units from each side, to prevent too acute triangles */
+               /* this kind of simulates "number of shiftWidth*shiftWidth fragments in the triangle not touched by an edge" */
 
                if(bestA < 0 || V > bestV)
                {