Killer Game Programming in Java

Creating the Landscape

Landscape's initial task is to build the terrain and the four walls around it. The resulting scene graph is shown in Figure 26-4.

The number of TexturedPlanes objects will vary depending on the height of the generated quads. Each TexturedPlanes holds all the quads within a given height range, therefore allowing them to be assigned the same texture. This means that the program only has to create one texture per TexturedPlanes object as opposed to one texture for each quad, a significant reduction in the number of objects.

Figure 26-4. Landscape's scene graph

The moving viewpoint hugs the landscape by utilizing Java 3D picking. I'll explain the details later, but it involves shooting a pick ray straight down underneath the viewpoint to hit a quad in the floor. The (x, y, z) coordinate of the intersection with the quad is obtained, and the y-value is used to set the y-axis position of the viewpoint.

The TexturedPlanes are grouped under the floorBG BranchGroup so picking can be localized to everything below floorBG, excluding the walls attached to the landBG BranchGroup.

No TransformGroup nodes are in the graph, and landBG is attached directly to the top-level sceneBG node. This means that the local coordinates used inside the TexturedPlanes and ColouredPlane objects are scene coordinates, and mapping between local and world values is unnecessary. This is an important ...