package com.test;

import com.jogamp.opengl.glu.GLU;

/**
 *
 * @author yogesh.mevada
 */
public class Camera {

    protected double[] eyeLoc = new double[3];

    protected double[] directionVec = new double[3];

    protected double[] viewLoc;

    protected double radius;

    protected double theta;

    protected double phi;

    Camera(float radius, double theta, double phi) {
        this.radius = radius;
        this.theta = theta;
        this.phi = phi;
        viewLoc = new double[]{0, 0, 0};
    }

    void resetCamera(GLU glu) {
        glu.gluLookAt(eyeLoc[0], eyeLoc[1], eyeLoc[2],
                viewLoc[0], viewLoc[1], viewLoc[2],
                directionVec[0], directionVec[1], directionVec[2]);
    }

    public void updateThetaPhi(double thetaInc, double phiInc) {
        theta += thetaInc;
        phi += phiInc;
        calcEyePosition();
    }

    public void updateRadius(double radiusInc) {
        radius += radiusInc;
        calcEyePosition();
    }

    public void updateViewLocation(double[] viewLoc) {
        this.viewLoc = viewLoc;
        calcEyePosition();
    }

    private void calcEyePosition() {
        double cy, cz, sy, sz;
        cy = Math.cos(theta);
        sy = Math.sin(theta);
        cz = Math.cos(phi);
        sz = Math.sin(phi);

        eyeLoc[0] = radius * cy * cz + viewLoc[0];
        eyeLoc[1] = radius * sz + viewLoc[1];
        eyeLoc[2] = -radius * sy * cz + viewLoc[2];

        directionVec[0] = -cy * sz;
        directionVec[1] = cz;
        directionVec[2] = sy * sz;

        // To keep the camera always pointing upwards, if the y-component
        // of the up vector is negative, invert the whole up vector    
        if (directionVec[1] < 0) {
            directionVec[0] = -directionVec[0];
            directionVec[1] = -directionVec[1];
            directionVec[2] = -directionVec[2];
        }
    }
}