From 0e1509947917e11a18416eba2a51e90e4a315b7c Mon Sep 17 00:00:00 2001
From: liabru <liabru@brm.io>
Date: Wed, 3 May 2017 21:28:39 +0100
Subject: [PATCH] improved Example.catapult using pin constraint

---
 examples/catapult.js | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/examples/catapult.js b/examples/catapult.js
index 64c4965..7fa0809 100644
--- a/examples/catapult.js
+++ b/examples/catapult.js
@@ -9,7 +9,9 @@ Example.catapult = function() {
         MouseConstraint = Matter.MouseConstraint,
         Mouse = Matter.Mouse,
         World = Matter.World,
-        Bodies = Matter.Bodies;
+        Bodies = Matter.Bodies,
+        Body = Matter.Body,
+        Vector = Matter.Vector;
 
     // create engine
     var engine = Engine.create(),
@@ -35,20 +37,27 @@ Example.catapult = function() {
     Runner.run(runner, engine);
 
     // add bodies
+    var group = Body.nextGroup(true);
+
     var stack = Composites.stack(250, 255, 1, 6, 0, 0, function(x, y) {
         return Bodies.rectangle(x, y, 30, 30);
     });
 
-    var catapult = Bodies.rectangle(400, 520, 320, 20);
+    var catapult = Bodies.rectangle(400, 520, 320, 20, { collisionFilter: { group: group } });
 
     World.add(world, [
         stack,
         catapult,
         Bodies.rectangle(400, 600, 800, 50.5, { isStatic: true }),
         Bodies.rectangle(250, 555, 20, 50, { isStatic: true }),
+        Bodies.rectangle(400, 535, 20, 80, { isStatic: true, collisionFilter: { group: group } }),
         Bodies.circle(560, 100, 50, { density: 0.005 }),
-        Constraint.create({ bodyA: catapult, pointB: { x: 390, y: 580 } }),
-        Constraint.create({ bodyA: catapult, pointB: { x: 410, y: 580 } })
+        Constraint.create({ 
+            bodyA: catapult, 
+            pointB: Vector.clone(catapult.position),
+            stiffness: 1,
+            length: 0
+        })
     ]);
 
     // add mouse control