lineshape.java

用java3d做的一个粒子系统可以控制粒子运动

import javax.media.j3d.*;
import javax.vecmath.*;

final class LineShape extends LineArray {

    private Point3d[] coord;
    private Color3f[] color;

    private int numPoints;
    private double invNumPoints;

    private Transform3D rotate=new Transform3D();
    private Transform3D translate=new Transform3D();
    private Vector3d vec=new Vector3d();

    // scratch vars
    private Color3f tmpcolor=new Color3f();
    private Point3d p0=new Point3d(),
	p1=new Point3d(),
	p2=new Point3d();

    public LineShape(int numPoints){
        super(4*numPoints,COLOR_3 | COORDINATES);
        
        this.numPoints=numPoints;
	invNumPoints = 1.0/numPoints;
	
        int nCoord=4*numPoints;


        setCapability(ALLOW_COLOR_WRITE);
        setCapability(ALLOW_COORDINATE_WRITE);
        
        coord=new Point3d[nCoord];
        color=new Color3f[nCoord];
        for(int i=0;i<nCoord;i++){
            coord[i]=new Point3d();
            color[i]=new Color3f();
        }
    }


    void update(double localTime){


        int count=0;
        for(int i=numPoints; --i>=0; ){
                    
            double s = ((double)i) / numPoints;
            double t = localTime*s;

	    int radius_idx = (int) (0xffff & (long)((15646.0*t)));
            double radius=1.0+.5*Particles.COS[radius_idx];
            
            rotate.rotZ((t*Math.PI/10) % Math.PI*2);
            vec.set(radius,0,0);
            translate.setTranslation(vec);
            
            int sweep_time_idx = (int) (0xffff & (long) (32768*localTime+65536*s));
            double sweep = Particles.SIN[sweep_time_idx];
            double rad_cos = Particles.COS[sweep_time_idx];
            double rad = .1 * (1+rad_cos);
            double c = 8*rad-.8;
            int angle_idx = (int) (0xffff & (long)(8192*sweep));
            double x = rad * Particles.COS[angle_idx];
            double y = rad * Particles.SIN[angle_idx];
            double z = Particles.SIN[(int)(0xffff & (long)(13451*t))];
            
            rotate.mul(translate);
            
            tmpcolor.set((float)(.4+3*rad*s),
			 (float)(rad*(2*z+3)),
			 (float)(c*c+.3f));
            
            p0.set(x,y,z);
            p1.set(0,0,z);
            p2.set(-x,y,z);
            
            rotate.transform(p0);
            rotate.transform(p1);
            rotate.transform(p2);
            
            color[count].set(tmpcolor); coord[count++].set(p0); 
            color[count].set(tmpcolor); coord[count++].set(p1);
            color[count].set(tmpcolor); coord[count++].set(p1); 
            color[count].set(tmpcolor); coord[count++].set(p2); 
        }
        
        
        setCoordinates(0,coord);
        setColors(0,color);
    }        
}