/** Ray tracer camera (observer)
 * Cylindrical Equal-Area version for fast pan
 * @author: Phil Gage
 */
class CylindricalCamera extends AbstractCamera {
    double xtable[];
    double ytable[];
    double ztable[];

    CylindricalCamera (World world, int width, int height) {
        super (world, width, height);
        xtable = new double[width];
        ytable = new double[height];
        ztable = new double[width];
        update();
    }

    void update() {
        // Save equal-angle XZ values on circular arc of cylinder
//        double radius = width / fov; //uniform
        double radius = 1.0;
        double theta = az-fov/2.0;
        double delta = fov/width;
        for (int i=0; i<width; i++) {
            xtable[i] = radius * Math.sin(theta);
            ztable[i] = radius * Math.cos(theta);
            theta += delta;
        }

        // Save equal-angle Y values using tan
        theta = el-vfov/2.0;
        delta = vfov/height;
        for (int i=0; i<height; i++) {
            ytable[i] = Math.tan(theta);
            theta += delta;
        }
    }


    /** Get primary ray from eye thru pixel */
    void primaryRay (int x, int y, Ray r) {
        r.origin.set(eye);
        r.direction.x = xtable[x];
//        r.direction.y = y - height/2; //uniform
        r.direction.y = ytable[y]; //equal area
        r.direction.z = ztable[x];
        r.direction.normalize();
    }

}