Killer Game Programming in Java

Creating the Scene

The WrapTrees3D class creates the scene: the checkerboard floor, the background, the lights, and an OrbitBehavior allow the user to move around.

Most of the tree-related activity is started in growTrees(), which creates five TransformGroups and five TreeLimb objects. The code fragment shows one of these TransformGroups and TreeLimbs:

    // starting position for the first tree: (0,0,-5)
    Transform3D t3d = new Transform3D();
    t3d.set( new Vector3f(0,0,-5));
    TransformGroup tg0 = new TransformGroup(t3d);
    sceneBG.addChild(tg0);


    // create the tree
    TreeLimb t0 = new TreeLimb(Z_AXIS, 0, 0.05f, 0.5f, tg0, null);

The TransformGroup reference (tg0) is passed to the TreeLimb constructor, where it's used to position the limb.

Loading Leaves

growTrees() loads a sequence of leaf images, storing them in an ImageComponent2D array. This increases efficiency because each TreeLimb will utilize this array if it requires leaves rather than loading its own copy of the images:

    // load the leaf images used by all the trees
    ImageComponent2D[] leafIms = loadImages("images/leaf", 6);

The loadImages() method is shown here:

 private ImageComponent2D[] loadImages(String fNms, int numIms) /* Load the leaf images: they all start with fNms, and there are numIms of them. */ { String filename; TextureLoader loader; ImageComponent2D[] ims = new ImageComponent2D[numIms]; System.out.println("Loading " + numIms +" textures from "+ fNms); for (int i=0; i < numIms; i++) { filename = new String(fNms + i + ".gif"); ...