tweaking

src/game.c

@@ -757,20 +757,15 @@ INTERNAL void game_update(struct game_cmd_array game_cmds)
             pen = epa(e0_poly, e1_poly, simplex);
 
             if (colliding) {
+#if 0
             /* Pen movement test */
-#if 1
                 {
                     struct xform xf = e1_xf;
-
-                    //xf.og = v2_add(xf.og, v2_div(pen, 2));
                     xf.og = v2_add(xf.og, pen);
-
                     entity_set_xform(e1, xf);
-                    e1->verlet_xform = xf;
+                    //e1->verlet_xform.og = v2_add(e1->verlet_xform.og, pen);
                 }
 #endif
-
-                break;
             }
         }
 

src/util.c

@@ -214,6 +214,7 @@ struct v2 epa(struct v2_array poly0, struct v2_array poly1, struct simplex simpl
         }
 
         /* Insert point into prototype array */
+        /* FIXME: Preserve winding order */
         arena_push(scratch.arena, struct v2);
         ++proto_count;
         for (u32 i = proto_count - 1; i > pen_pe_index; --i) {
@@ -268,3 +269,22 @@ struct v2_array menkowski(struct arena *arena, struct v2_array poly0, struct v2_
     return res;
 #endif
 }
+
+/* Returns 1 if winding forward, -1 if backward */
+i32 poly_get_winding_order(struct v2_array poly)
+{
+    i32 res;
+    if (poly.count >= 3) {
+        struct v2 a = poly.points[0];
+        struct v2 b = poly.points[1];
+        struct v2 c = poly.points[2];
+        if (v2_wedge(v2_sub(b, a), v2_sub(c, b)) > 0) {
+            res = 1;
+        } else {
+            res = -1;
+        }
+    } else {
+        res = -1;
+    }
+    return res;
+}

src/util.h

@@ -201,5 +201,6 @@ struct v2 normal_towards_point(struct v2 start, struct v2 end, struct v2 p);
 struct gjk_result gjk(struct v2_array poly0, struct v2_array poly1);
 struct v2 epa(struct v2_array poly0, struct v2_array poly1, struct simplex simplex);
 struct v2_array menkowski(struct arena *arena, struct v2_array poly0, struct v2_array poly1);
+i32 poly_get_winding_order(struct v2_array poly);
 
 #endif