oop-labs-collection/labs/3/renderSuite/Sphere.java

package renderSuite;

import renderSuite.Vec3;
import renderSuite.Util;
import renderSuite.Ray;

public class Sphere extends Surface {
    double r;

    public Sphere(Vec3 position, Vec3 color, double radius) {
        this.p = position;
        this.c = color;
        this.r = radius;
    }

    public void main() {

    }

    public boolean intersect(Ray r) {
        // OLD
        //double dist = Util.d(ray_position, position);
        //return (Util.d(ray_position, position) <= radius);

        // using RTX
        Vec3 l = new Vec3(this.p.x - r.p.x,
                          this.p.y - r.p.y,
                          this.p.z - r.p.z);

        Vec3 nl = l.get_norm();
        double cosine = Util.dot(r.f, nl);
        
        // >90 degrees = no intersection
        if (cosine < 0) {
            return false;
        }

        double tc = l.len() * cosine;
        double d = Math.sqrt( l.len()*l.len() - tc*tc );
        
        return (d < this.r);
    }
}