Time for action – creating a ground in the world

Carry out the following steps to create a static ground:

1. Open the box2dcargame.js JavaScript file.
2. Define the following pxPerMeter variable in the file; this is the unit setting in the Box2D world:

   var pxPerMeter = 30; // 30 pixels = 1 meter

3. Add the following function to the end of the JavaScript file; this creates a fixed body as the playground:

   function createGround() {
     var bodyDef = new b2BodyDef;
     var fixDef = new b2FixtureDef;
   
     bodyDef.type = b2Body.b2_staticBody;
     bodyDef.position.x = 250/pxPerMeter;
     bodyDef.position.y = 370 /pxPerMeter;
   
     fixDef.shape = new b2PolygonShape();
     fixDef.shape.SetAsBox(250/pxPerMeter, 25/pxPerMeter);
     fixDef.restitution = 0.4;
   
     // create the body from the definition.
     var body = carGame.world.CreateBody(bodyDef);
     body.CreateFixture(fixDef);
   
     return body;
   }

4. Call the createGround function in the initGame function after we have created the world as follows:

   createGround();

5. As we are still...