demos/car.html

<!DOCTYPE html>
<html>
<head>
    <title>Car demo - p2.js physics engine</title>
    <script src="../build/p2.js"></script>
    <script src="../build/p2.renderer.js"></script>
    <link href="css/demo.css" rel="stylesheet"/>
    <meta name="description" content="How to make a simple box car with a motor.">
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
</head>
<body>
    <script>

        // Create demo application
        var app = new p2.WebGLRenderer(function(){

            // Create a World
            var world = new p2.World({
                gravity: [0,-10] // Set gravity to -10 in y direction
            });

            this.setWorld(world);

            // Set high friction so the wheels don't slip
            world.defaultContactMaterial.friction = 100;

            // Create ground shape (plane)
            planeShape = new p2.Plane();

            // Create a body for the ground
            planeBody = new p2.Body({
                mass:0  // Mass == 0 makes the body static
            });
            planeBody.addShape(planeShape); // Add the shape to the body
            world.addBody(planeBody);       // Add the body to the World

            // Add circle bump in the center
            circleShape = new p2.Circle({ radius: 2 }); // Circle shape of radius 2
            circleBody = new p2.Body({
                position:[0, -1] // Set initial position
            });
            circleBody.addShape(circleShape);
            world.addBody(circleBody);

            // Create chassis for our car
            chassisBody = new p2.Body({
                mass : 1,        // Setting mass > 0 makes it dynamic
                position: [-4,1] // Initial position
            });
            chassisShape = new p2.Box({ width: 1, height: 0.5 });                     // Chassis shape is a rectangle
            chassisBody.addShape(chassisShape);
            world.addBody(chassisBody);

            // Create wheels
            wheelBody1 = new p2.Body({ mass : 1, position:[chassisBody.position[0] - 0.5,0.7] });
            wheelBody2 = new p2.Body({ mass : 1, position:[chassisBody.position[0] + 0.5,0.7] });
            wheelShape1 = new p2.Circle({ radius: 0.2 });
            wheelShape2 = new p2.Circle({ radius: 0.2 });
            wheelBody1.addShape(wheelShape1);
            wheelBody2.addShape(wheelShape2);
            world.addBody(wheelBody1);
            world.addBody(wheelBody2);

            // Constrain wheels to chassis with revolute constraints.
            // Revolutes lets the connected bodies rotate around a shared point.
            revoluteBack = new p2.RevoluteConstraint(chassisBody, wheelBody1, {
                localPivotA: [-0.5, -0.3],   // Where to hinge first wheel on the chassis
                localPivotB: [0, 0],
                collideConnected: false
            });
            revoluteFront = new p2.RevoluteConstraint(chassisBody, wheelBody2, {
                localPivotA: [0.5, -0.3], // Where to hinge second wheel on the chassis
                localPivotB: [0, 0],      // Where the hinge is in the wheel (center)
                collideConnected: false
            });
            world.addConstraint(revoluteBack);
            world.addConstraint(revoluteFront);

            // Enable the constraint motor for the back wheel
            revoluteBack.enableMotor();
            revoluteBack.setMotorSpeed(10); // Rotational speed in radians per second

            this.frame(0, 0, 8, 6);
        });

    </script>
</body>
</html>