fixes for compound bodies

liabru · Feb 4, 2015 · 87f9065 · 87f9065
1 parent 10e5d0f
commit 87f9065
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Showing 4 changed files with 39 additions and 27 deletions.
diff --git a/src/body/Body.js b/src/body/Body.js
@@ -402,6 +402,9 @@ var Body = {};
             Vertices.rotate(part.vertices, delta, body.position);
             Axes.rotate(part.axes, delta);
             Bounds.update(part.bounds, part.vertices, body.velocity);
+            if (i > 0) {
+                Vector.rotateAbout(part.position, delta, body.position, part.position);
+            }
         }
     };
 
@@ -528,16 +531,23 @@ var Body = {};
         // transform the body geometry
         for (var i = 0; i < body.parts.length; i++) {
             var part = body.parts[i];
+
             Vertices.translate(part.vertices, body.velocity);
-            if (body.angularVelocity !== 0) {
-                Vertices.rotate(part.vertices, body.angularVelocity, body.position);
-                Axes.rotate(part.axes, body.angularVelocity);
-            }
-            Bounds.update(part.bounds, body.vertices, body.velocity);
+
             if (i > 0) {
                 part.position.x += body.velocity.x;
                 part.position.y += body.velocity.y;
             }
+
+            if (body.angularVelocity !== 0) {
+                Vertices.rotate(part.vertices, body.angularVelocity, body.position);
+                Axes.rotate(part.axes, body.angularVelocity);
+                if (i > 0) {
+                    Vector.rotateAbout(part.position, body.angularVelocity, body.position, part.position);
+                }
+            }
+
+            Bounds.update(part.bounds, part.vertices, body.velocity);
         }
     };
 

diff --git a/src/collision/Resolver.js b/src/collision/Resolver.js
@@ -91,22 +91,18 @@ var Resolver = {};
             var body = bodies[i];
 
             if (body.positionImpulse.x !== 0 || body.positionImpulse.y !== 0) {
-                // move the body without changing velocity
-                body.position.x += body.positionImpulse.x;
-                body.position.y += body.positionImpulse.y;
-                body.positionPrev.x += body.positionImpulse.x;
-                body.positionPrev.y += body.positionImpulse.y;
-
                 // update body geometry
                 for (var j = 0; j < body.parts.length; j++) {
                     var part = body.parts[j];
                     Vertices.translate(part.vertices, body.positionImpulse);
-                    Bounds.update(part.bounds, body.vertices, body.velocity);
-                    if (j > 0) {
-                        part.position.x += body.positionImpulse.x;
-                        part.position.y += body.positionImpulse.y;
-                    }
+                    Bounds.update(part.bounds, part.vertices, body.velocity);
+                    part.position.x += body.positionImpulse.x;
+                    part.position.y += body.positionImpulse.y;
                 }
+
+                // move the body without changing velocity
+                body.positionPrev.x += body.positionImpulse.x;
+                body.positionPrev.y += body.positionImpulse.y;
 
                 // dampen accumulator to warm the next step
                 body.positionImpulse.x *= _positionWarming;

diff --git a/src/constraint/Constraint.js b/src/constraint/Constraint.js
@@ -251,20 +251,24 @@ var Constraint = {};
             // update geometry and reset
             for (var j = 0; j < body.parts.length; j++) {
                 var part = body.parts[j];
+
                 Vertices.translate(part.vertices, impulse);
 
+                if (j > 0) {
+                    part.position.x += impulse.x;
+                    part.position.y += impulse.y;
+                }
+
                 if (impulse.angle !== 0) {
                     Vertices.rotate(part.vertices, impulse.angle, body.position);
                     Axes.rotate(part.axes, impulse.angle);
+                    if (j > 0) {
+                        Vector.rotateAbout(part.position, impulse.angle, body.position, part.position);
+                    }
                     impulse.angle = 0;
                 }
 
-                Bounds.update(part.bounds, body.vertices);
-
-                if (j > 0) {
-                    part.position.x += impulse.x;
-                    part.position.y += impulse.y;
-                }
+                Bounds.update(part.bounds, part.vertices);
             }
 
             impulse.x = 0;

diff --git a/src/geometry/Vector.js b/src/geometry/Vector.js
@@ -77,14 +77,16 @@ var Vector = {};
      * @param {vector} vector
      * @param {number} angle
      * @param {vector} point
+     * @param {vector} [output]
      * @return {vector} A new vector rotated about the point
      */
-    Vector.rotateAbout = function(vector, angle, point) {
+    Vector.rotateAbout = function(vector, angle, point, output) {
         var cos = Math.cos(angle), sin = Math.sin(angle);
-        return {
-            x: point.x + ((vector.x - point.x) * cos - (vector.y - point.y) * sin),
-            y: point.y + ((vector.x - point.x) * sin + (vector.y - point.y) * cos)
-        };
+        if (!output) output = {};
+        var x = point.x + ((vector.x - point.x) * cos - (vector.y - point.y) * sin);
+        output.y = point.y + ((vector.x - point.x) * sin + (vector.y - point.y) * cos);
+        output.x = x;
+        return output;
     };
 
     /**