added second pass for constraint solving

Author: liabru

src/constraint/Constraint.js

@@ -21,10 +21,8 @@ var Common = require('../core/Common');
 
 (function() {
 
-    var _zeroVector = { x: 0, y: 0 };
-
     Constraint._warming = 0.4;
-    Constraint._torqueDampen = 0.8;
+    Constraint._torqueDampen = 1;
     Constraint._minLength = 0.000001;
 
     /**
@@ -121,8 +119,8 @@ var Common = require('../core/Common');
             fixedB = !constraint.bodyB || (constraint.bodyB && constraint.bodyB.isStatic);
 
             if (!fixedA && !fixedB) {
-            Constraint.solve(constraints[i], timeScale);
-        }
+                Constraint.solve(constraints[i], timeScale);
+            }
         }
     };
 

src/core/Engine.js

@@ -149,7 +149,7 @@ var Body = require('../body/Body');
         // update all body position and rotation by integration
         _bodiesUpdate(allBodies, delta, timing.timeScale, correction, world.bounds);
 
-        // update all constraints
+        // update all constraints (first pass)
         Constraint.preSolveAll(allBodies);
         for (i = 0; i < engine.constraintIterations; i++) {
             Constraint.solveAll(allConstraints, timing.timeScale);
@@ -158,7 +158,6 @@ var Body = require('../body/Body');
 
         // broadphase pass: find potential collision pairs
         if (broadphase.controller) {
-
             // if world is dirty, we must flush the whole grid
             if (world.isModified)
                 broadphase.controller.clear(broadphase);
@@ -167,7 +166,6 @@ var Body = require('../body/Body');
             broadphase.controller.update(broadphase, allBodies, engine, world.isModified);
             broadphasePairs = broadphase.pairsList;
         } else {
-
             // if no broadphase set, we just pass all bodies
             broadphasePairs = allBodies;
         }
@@ -201,6 +199,13 @@ var Body = require('../body/Body');
         }
         Resolver.postSolvePosition(allBodies);
 
+        // update all constraints (second pass)
+        Constraint.preSolveAll(allBodies);
+        for (i = 0; i < engine.constraintIterations; i++) {
+            Constraint.solveAll(allConstraints, timing.timeScale);
+        }
+        Constraint.postSolveAll(allBodies);
+
         // iteratively resolve velocity between collisions
         Resolver.preSolveVelocity(pairs.list);
         for (i = 0; i < engine.velocityIterations; i++) {