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The Static Buffers The static buffer of 3D
The Static Buffers The static buffer of 3D coordinates is used for storing the VCS vertices before the projection. It is static because only one camera at a time will use it. The static buffer of two-dimensional coordinates is used for projection. It will be borrowed to the caller so that it can use it for rendering the polyhedrons. Calculating Screen Distance with Respect to the View Angle When constructing a camera, the view angle has to be specified. Using this argument and the width of the screen, we can calculate the screen distance with a trigonometric operation, as in Figure 11-21. Figure 11-21 Calculating the screen distance The Private updateMatrix() Method Every time the position or orientation changes, the transformation matrix is marked as dirty. The updateMatrix() method checks to see if the matrix is dirty, and if it is, it is recalculated. The project() Method The project() method is fed with an array of 3D coordinates from the WCS. The coordinates will be transformed to the VCS and then projected into the 2D buffer. The 2D buffer will be returned from the method so that the caller can use it. Implementing the 3D Point Class (fPoint3d) To make the handling of 3D coordinates smoother, a 3D point class is introduced in Listing 11-9. There are no surprises in this class, and it needs no further comments. Listing 11-9 The fPoint3d class public class fPoint3d{ public double x; public double y; public double z; public fPoint3d (double x0, double y0, double z0) { x=x0; y=y0; z=z0; } public fPoint3d () { x=y=z=0;
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