Combine consecutive duplicate points in polygons to remove zero-length edges. Fixes #55 (#59)

Author: jriecken

SAT.js

@@ -310,7 +310,7 @@
   }
   SAT['Polygon'] = Polygon;
 
-  // Set the points of the polygon.
+  // Set the points of the polygon. Any consecutive duplicate points will be combined.
   //
   // Note: The points are counter-clockwise *with respect to the coordinate system*.
   // If you directly draw the points on a screen that has the origin at the top-left corner
@@ -331,6 +331,14 @@
       var normals = this['normals'] = [];
       // Allocate the vector arrays for the calculated properties
       for (i = 0; i < points.length; i++) {
+        // Remove consecutive duplicate points
+        var p1 = points[i];
+        var p2 = i < points.length - 1 ? points[i + 1] : points[0];
+        if (p1 !== p2 && p1.x === p2.x && p1.y === p2.y) {
+          points.splice(i, 1);
+          i -= 1;
+          continue;
+        }
         calcPoints.push(new Vector());
         edges.push(new Vector());
         normals.push(new Vector());

package.json

@@ -8,10 +8,7 @@
     "sat",
     "game"
   ],
-  "license": {
-    "type": "MIT",
-    "url": "http://github.com/jriecken/sat-js/raw/master/LICENSE"
-  },
+  "license": "MIT",
   "repository": {
     "type": "git",
     "url": "git://github.com/jriecken/sat-js.git"

test/test.js

@@ -92,6 +92,32 @@ describe("Collision", function() {
     assert(!collided);
   });
 
+  it('testPolygonCircle - line - not collide', function () {
+    var V = SAT.Vector;
+    var C = SAT.Circle;
+    var B = SAT.Box;
+
+    var circle = new C(new V(50,50), 20);
+    var polygon = new B(new V(1000,1000), 100, 0).toPolygon();
+    var response = new SAT.Response();
+    var collided = SAT.testPolygonCircle(polygon, circle, response);
+    assert(!collided);
+  })
+
+  it('testPolygonCircle - line - collide', function () {
+    var V = SAT.Vector;
+    var C = SAT.Circle;
+    var B = SAT.Box;
+
+    var circle = new C(new V(50,50), 20);
+    var polygon = new B(new V(50,50), 100, 0).toPolygon();
+    var response = new SAT.Response();
+    var collided = SAT.testPolygonCircle(polygon, circle, response);
+
+    assert(collided);
+    assert(response.overlap.toFixed(2) == "20.00");
+  })
+
   it("testPolygonPolygon", function() {
     var V = SAT.Vector;
     var P = SAT.Polygon;