Groovy example source code file (raytracer.java)

This example Groovy source code file (raytracer.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Groovy tags/keywords

group, hit, hit, linkedlist, listiterator, p5\n, ray, ray, scene, scene, sphere, util, vec, vec

The Groovy raytracer.java source code

// The Great Computer Language Shootout
// http://shootout.alioth.debian.org/
// Fastest version under 100 LOC. Contributed by Jon Harrop, 2005

import java.util.*;
public final class raytracer {
    // Use "double delta=Math.sqrt(Math.ulp(1.0))" with Java 1.5 or better
    double delta=Math.sqrt(2.22044604925031e-16), infinity=Float.POSITIVE_INFINITY;
    class Vec {
	public double x, y, z;
	public Vec(double x2, double y2, double z2) { x=x2; y=y2; z=z2; }
    }
    Vec add(Vec a, Vec b) { return new Vec(a.x+b.x, a.y+b.y, a.z+b.z); }
    Vec sub(Vec a, Vec b) { return new Vec(a.x-b.x, a.y-b.y, a.z-b.z); }
    Vec scale(double s, Vec a) { return new Vec(s*a.x, s*a.y, s*a.z); }
    double dot(Vec a, Vec b) { return a.x*b.x + a.y*b.y + a.z*b.z; }
    Vec unitise(Vec a) { return scale(1 / Math.sqrt(dot(a, a)), a); }
    class Ray {
	public Vec orig, dir;
	public Ray(Vec o, Vec d) { orig=o; dir=d; }
    }
    class Hit {
	public double lambda;
	public Vec normal;
 	public Hit(double l, Vec n) { lambda=l; normal=n; }
    }
    abstract class Scene {
	abstract public Hit intersect(Hit i, Ray ray);
    }
    class Sphere extends Scene {
	public Vec center;
	public double radius;
	public Sphere(Vec c, double r) { center=c; radius=r; }
	public double ray_sphere(Ray ray) {
	    Vec v = sub(center, ray.orig);
	    double b = dot(v, ray.dir),
		disc = b*b - dot(v, v) + radius*radius;
	    if (disc < 0) return infinity;
	    double d = Math.sqrt(disc), t2 = b+d;
	    if (t2 < 0) return infinity;
	    double t1 = b-d;
	    return (t1 > 0 ? t1 : t2);
	}
	public Hit intersect(Hit i, Ray ray) {
	    double l = ray_sphere(ray);
	    if (l >= i.lambda) return i;
	    Vec n = add(ray.orig, sub(scale(l, ray.dir), center));
	    return new Hit(l, unitise(n));
	}
    }
    class Group extends Scene {
	public Sphere bound;
	public LinkedList objs;
	public Group(Sphere b) {
	    bound = b;
	    objs = new LinkedList();
	}
	public Hit intersect(Hit i, Ray ray) {
	    double l = bound.ray_sphere(ray);
	    if (l >= i.lambda) return i;
	    ListIterator it = objs.listIterator(0);
	    while (it.hasNext()) {
		Scene scene = (Scene)it.next();
		i = scene.intersect(i, ray);
	    }
	    return i;
	}
    }
    double ray_trace(Vec light, Ray ray, Scene scene) {
	Hit i = scene.intersect(new Hit(infinity, new Vec(0, 0, 0)), ray);
	if (i.lambda == infinity) return 0;
	Vec o = add(ray.orig, add(scale(i.lambda, ray.dir),
				  scale(delta, i.normal)));
	double g = dot(i.normal, light);
	if (g >= 0) return 0.;
	Ray sray = new Ray(o, scale(-1, light));
	Hit si = scene.intersect(new Hit(infinity, new Vec(0, 0, 0)), sray);
	return (si.lambda == infinity ? -g : 0);
    }
    Scene create(int level, Vec c, double r) {
	Sphere sphere = new Sphere(c, r);
	if (level == 1) return sphere;
	Group group = new Group(new Sphere(c, 3*r));
	group.objs.addLast(sphere);
	double rn = 3*r/Math.sqrt(12);
	for (int dz=-1; dz<=1; dz+=2)
	    for (int dx=-1; dx<=1; dx+=2) {
		Vec c2 = new Vec(c.x+dx*rn, c.y+rn, c.z+dz*rn);
		group.objs.addLast(create(level-1, c2, r/2));
	    }
	return group;
    }
    void run(int n, int level, int ss) {
	Scene scene = create(level, new Vec(0, -1, 0), 1);
	System.out.print("P5\n"+n+" "+n+"\n255\n");
	for (int y=n-1; y>=0; --y)
	    for (int x=0; x<n; ++x) {
		double g=0;
		for (int dx=0; dx<ss; ++dx)
		    for (int dy=0; dy<ss; ++dy) {
			Vec d = new Vec(x+dx*1./ss-n/2., y+dy*1./ss-n/2., n);
			Ray ray = new Ray(new Vec(0, 0, -4), unitise(d));
			g += ray_trace(unitise(new Vec(-1, -3, 2)),
				       ray, scene);
		    }
                System.out.print((char)(.5+255*g/(ss*ss)));
	    }
    }
    public static void main(String[] args) {
	(new raytracer()).run(Integer.parseInt(args[0]), 6, 4);
    }
}