X-Git-Url: http://pileus.org/git/?p=grits;a=blobdiff_plain;f=src%2Froam.c;h=0f4995e0b56593d7bf3dc03f4d65015afb847e8e;hp=21b1393c6c902b0202d045ffed0821826840934c;hb=907e81475ed6b87e2a2a918aa32836345005074a;hpb=850e596cffb982eab6672930c15eb078f1cb737b

diff --git a/src/roam.c b/src/roam.c
index 21b1393..0f4995e 100644
--- a/src/roam.c
+++ b/src/roam.c
@@ -319,7 +319,6 @@ static void roam_triangle_sync_neighbors(RoamTriangle *neigh, RoamTriangle *old,
 	if      (neigh->t.l == old) neigh->t.l = new;
 	else if (neigh->t.b == old) neigh->t.b = new;
 	else if (neigh->t.r == old) neigh->t.r = new;
-	else g_assert_not_reached();
 }
 
 static gboolean roam_triangle_visible(RoamTriangle *triangle, RoamSphere *sphere)
@@ -338,6 +337,20 @@ static gboolean roam_triangle_visible(RoamTriangle *triangle, RoamSphere *sphere
 	         l->pz < 1 && m->pz < 1 && r->pz < 1;
 }
 
+static gboolean roam_triangle_backface(RoamTriangle *triangle, RoamSphere *sphere)
+{
+	RoamPoint *l = triangle->p.l;
+	RoamPoint *m = triangle->p.m;
+	RoamPoint *r = triangle->p.r;
+	roam_point_update_projection(l, sphere->view);
+	roam_point_update_projection(m, sphere->view);
+	roam_point_update_projection(r, sphere->view);
+	double size = -( l->px * (m->py - r->py) +
+			 m->px * (r->py - l->py) +
+			 r->px * (l->py - m->py) ) / 2.0;
+	return size < 0;
+}
+
 /**
  * roam_triangle_update_errors:
  * @triangle: the triangle
@@ -375,6 +388,12 @@ void roam_triangle_update_errors(RoamTriangle *triangle, RoamSphere *sphere)
 
 		/* Size < 0 == backface */
 		triangle->error *= size;
+
+		/* Give some preference to "edge" faces */
+		if (roam_triangle_backface(triangle->t.l, sphere) ||
+		    roam_triangle_backface(triangle->t.b, sphere) ||
+		    roam_triangle_backface(triangle->t.r, sphere))
+			triangle->error *= 500;
 	}
 }
 
@@ -554,6 +573,11 @@ void roam_diamond_merge(RoamDiamond *diamond, RoamSphere *sphere)
 	b->kids[0] = b->kids[1] = NULL;
 
 	/* Add original triangles */
+	roam_triangle_sync_neighbors(s->t.l, sl, s);
+	roam_triangle_sync_neighbors(s->t.r, sr, s);
+	roam_triangle_sync_neighbors(b->t.l, bl, b);
+	roam_triangle_sync_neighbors(b->t.r, br, b);
+
 	roam_triangle_add(s, sl->t.b, b, sr->t.b, sphere);
 	roam_triangle_add(b, bl->t.b, s, br->t.b, sphere);