Hyperboloid.java

package com.gwief.jTrace;

/*
    Hyperboloid.java by Damian Newport
    Uses Quadric.java to implement a Hyperboloid
*/

public class Hyperboloid {

    public static final double[] intersect(Ray a){
        double[] box = Box.intersect(a);

        // do we hit the box?
        if (box.length == 0){
            return new double[0];
        }

        // if we got here we hit the box - lets test the Hyperboloid
        // move the hyp up so we don't get )( shape
        Ray ray = new Ray(a);
        ray.origin.y -= 0.5;
        
        
                                         // A,  B, C, J 
        double[] hyp = Quadric.intersect(ray, 4, -0.9, 4, -0.1);
 
        // do we hit the the hyperboloid
        if (hyp.length == 0){
            return new double[0];
        }
        
        if (rayTrace.bugmode){
            System.out.println("Hyperboloid.box[0] = " + box[0]);
            System.out.println("Hyperboloid.box[1] = " + box[1]);
            System.out.println("Hyperboloid.hyp[0] = " + hyp[0]);
            System.out.println("Hyperboloid.hyp[1] = " + hyp[1]);
        }
        
        // if we get here we've scored
        // now just have to work out where 

        double result[] = new double[4];
        result[0] = result[1] = hyp[0];
        result[2] = result[3] = hyp[1];
        
        return result;
    }
    
    public static final Vector3D normal(Vector3D a){
        
        /* if it intersects with the box bit */
        
        if ((0.5-a.y) < rayTrace.TINY){
            return new Vector3D(0,1,0);
        }
        if ((0.5+a.y) < rayTrace.TINY){
            return new Vector3D(0,-1,0);
        }

        /* move the hyp 'down' */
        Vector3D temp = new Vector3D(a);
        temp.y -= 0.5;
        
        /* else it intersects with the hyperboloid */
                                 /* A,  B, C, J */
        return Quadric.normal(temp, 4, -0.9, 4, -0.1);
    }

}