Lighting up the World

OK, the first example was a good start, but was it 3D? If you don't think a square qualifies as three-dimensional, you are going to need to add some lights to your universe. The way the light falls on an object provides us with the shading that helps us see shapes in three dimensions

The next example illustrates how to display a ball lit by a red light:

 

import com.sun.j3d.utils.geometry.*;

import com.sun.j3d.utils.universe.*;

import javax.media.j3d.*;

import javax.vecmath.*;

public class Ball {

public Ball() {

   // Create the universe

   SimpleUniverse universe = new SimpleUniverse();

   // Create a structure to contain objects

   BranchGroup group = new BranchGroup();

   // Create a ball and add it to the group of objects

   Sphere sphere = new Sphere(0.5f);

   group.addChild(sphere);

   // Create a red light that shines for 100m from the origin

   Color3f light1Color = new Color3f(1.8f, 0.1f, 0.1f);

   BoundingSphere bounds =

   new BoundingSphere(new Point3d(0.0,0.0,0.0), 100.0);

   Vector3f light1Direction = new Vector3f(4.0f, -7.0f, -12.0f);

   DirectionalLight light1

      = new DirectionalLight(light1Color, light1Direction);

   light1.setInfluencingBounds(bounds);

   group.addChild(light1);

   // look towards the ball

   universe.getViewingPlatform().setNominalViewingTransform();

   // add the group of objects to the Universe

   universe.addBranchGraph(group);

}

public static void main(String[] args) { new Ball(); }

}

The sphere we created is white (the default), it appears red because of the colored light. Since it is a DirectionalLight, we also have to specify how far the light shines and in what direction. In the example, the light shines for 100 meters from the origin and the direction is to the right, down and into the screen (this is defined by the vector: 4.0 right, -7.0 down, and -12.0 into the screen).

You can also create an AmbientLight which will produce a directionless light, or a SpotLight if you want to focus on a particular part of your scene. A combination of a strong directional light and a weaker ambient light gives a natural-looking appearance to your scene. Java 3D lights do not produce shadows.

Getting Started - Your First Program <<< Table of Contents >>> Positioning the Objects