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AddThis Social Bookmark Button O'Reilly Book Excerpts: Killer Game Programming in Java

Killer Game Programming in Java: A 3D Checkerboard, Part 2

Editor's note: In part one of this two-part excerpt from Killer Game Programming in Java, author Andrew Davison strode through some complex programming issues for developing Java 3D graphics, such as how to add shapes, lighting, and backgrounds to a Checkers3D application. Here in part two, Andrew continues the theme by demonstrating how to create a floating sphere for the Checkers3D app.

The Floor

The floor is made of tiles created with my ColouredTiles class, and axis labels made with the Java 3D Text2D utility class. Figure 15-5 shows the floor branch, previously hidden inside a "Floor Branch" box in Figure 15-3.

Figure 15-5
Figure 15-5. Floor branch of the scene graph

The floor subgraph is constructed with an instance of my CheckerFloor class and made available via the getBG( ) method:


    sceneBG.addChild( new CheckerFloor( ).getBG( ) );  // add the floor

The CheckerFloor( ) constructor uses nested for loops to initialize two ArrayLists. The blueCoords list contains all the coordinates for the blue tiles, and greenCoords holds the coordinates for the green tiles. Once the ArrayLists are filled, they are passed to ColouredTiles objects, along with the color that should be used to render the tiles. A ColouredTiles object is a subclass of Shape3D, so can be added directly to the floor's graph:


    floorBG.addChild( new ColouredTiles(blueCoords, blue) );
    floorBG.addChild( new ColouredTiles(greenCoords, green) );

The red square at the origin (visible in Figure 15-1) is made in a similar way:


    Point3f p1 = new Point3f(-0.25f, 0.01f, 0.25f);
    Point3f p2 = new Point3f(0.25f, 0.01f, 0.25f);
    Point3f p3 = new Point3f(0.25f, 0.01f, -0.25f);
    Point3f p4 = new Point3f(-0.25f, 0.01f, -0.25f);

    ArrayList oCoords = new ArrayList( );
    oCoords.add(p1); oCoords.add(p2);
    oCoords.add(p3); oCoords.add(p4);

    floorBG.addChild( new ColouredTiles(oCoords, medRed) );

The square is centered at (0, 0) on the XZ plane and raised a little above the y-axis (0.01 units) so it's visible above the tiles.

Each side of the square is the length of 0.5 units. The four Point3f points in the ArrayList are stored in a counterclockwise order. This is true for each group of four points in blueCoords and greenCoords. Figure 15-6 shows the ordering of the square's points.

Figure 15-6
Figure 15-6. OrigMarker, viewed from above

Pages: 1, 2, 3, 4

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