Emanuele Feronato

Quick 3D physics with Away3D 4.1 and Bullet Physics Engine

Talking about 3D, Actionscript 3 and Flash.

I really like when 3D and physics are easy to use, because game developers can delight us with new and original creations.

Two years ago I also made a 3D physics game called CubesOut, which was also licensed under the Pod Training name for the Mass Effect 3 official site.

Back to our days, here I am to show you probably the first tutorial you can find online about Away3D 4.1 and its integrated Bullet Physics Engine.

Everyting is commented in the code, which will allow you to create random cubes with the mouse. I know it’s quite simple but we are starting from the very beginning.

Here is the code:

package {
	// flash classes
	import flash.display.Sprite;
	import flash.events.Event;
	import flash.events.MouseEvent;
	import flash.geom.Vector3D;
	// away3d classes
	import away3d.containers.View3D;
	import away3d.entities.Mesh;
	import away3d.materials.ColorMaterial;
	import away3d.primitives.CubeGeometry;
	import away3d.lights.PointLight;
	import away3d.lights.LightBase;
	import away3d.materials.lightpickers.StaticLightPicker
	// awayphysics classes
	import awayphysics.collision.shapes.AWPBoxShape;
	import awayphysics.dynamics.AWPDynamicsWorld;
	import awayphysics.dynamics.AWPRigidBody;
	public class Main extends Sprite {
		// View3D is the Away3D world
		private var mainView:View3D;
		// AWPDynamicsWorld is the physics world
		private var world:AWPDynamicsWorld;
		// a point light, to add some (guess what?) light to the scene
		private var light:PointLight;
		public function Main() {
			// initializing the physics world
			world=AWPDynamicsWorld.getInstance();
			world.initWithDbvtBroadphase();
			// initializing the 3D world
			mainView = new View3D();
			addChild(mainView);
			// creating a new point light, all properties are easy to understand
			light = new PointLight();
            light.y = 1000;
            light.z = -700;
			light.color = 0xffff00;
			// adding the light to the scene
            mainView.scene.addChild(light);
			// setting camera position
			mainView.camera.z=-600;
			mainView.camera.y=500;
			// setting camera target
			mainView.camera.lookAt(new Vector3D(0,0,0));
			// the floor is a big rectangular cuboid, here is how we define it in Away3D
			var floorMesh:Mesh=new Mesh(new CubeGeometry(1000,5,1000));
			// defining a material
			var material:ColorMaterial=new ColorMaterial(0xa90000);
			// the material will be affected by light
			material.lightPicker = new StaticLightPicker([light]);
			// finally assigning the material to the floor cuboid
			floorMesh.material=material;
			// adding the cuboid to 3D world
			mainView.scene.addChild(floorMesh);
			// time to create its physics alter ego: notice AWPBoxShape and CubeGeometry have the same arguments
			var floorShape:AWPBoxShape=new AWPBoxShape(1000,5,1000);
			// link the physics cuboid with the 3D cuboid, the final "0" argument means it's static
			var floorRigidBody:AWPRigidBody=new AWPRigidBody(floorShape,floorMesh,0);
			// adding the physics body to the world
			world.addRigidBody(floorRigidBody);
			floorRigidBody.friction=1;
			floorRigidBody.position=new Vector3D(0,0,0);
			addEventListener(Event.ENTER_FRAME,update);
			stage.addEventListener(MouseEvent.CLICK,addCube);
		}
		// this function creates a cube in the same way seen before
		private function addCube(e:MouseEvent):void {
			var cubeMesh:Mesh=new Mesh(new CubeGeometry(50,50,50));
			cubeMesh.material=new ColorMaterial();
			cubeMesh.material.lightPicker = new StaticLightPicker([light]);
			mainView.scene.addChild(cubeMesh);
			var cubeShape:AWPBoxShape=new AWPBoxShape(50,50,50);
			var cubeRigidBody:AWPRigidBody=new AWPRigidBody(cubeShape,cubeMesh,1); // notice the final "1" as it's dynamic
			world.addRigidBody(cubeRigidBody);
			cubeRigidBody.friction=1;
			cubeRigidBody.position=new Vector3D(Math.random()*600-300,400,Math.random()*600-300);
		}
		private function update(e:Event):void {
			// first, we iterate the physics engine...
			world.step(1/30, 1, 1/30);
			// then we render the 3D scene
			mainView.render();
		}
	}
}

And this is the result:

Click with the mouse to generate random cubes.

To get all required libraries, you have to download Away3D 4.1.0 Alpha and awayphysics.

Download the source code with all required libraries.