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   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
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   See the License for the specific language governing permissions and
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package org.apache.batik.ext.awt.image;

import java.awt.Color;

A light source which emits a light of constant intensity in all directions.
Author:
Vincent Hardy
Version:
$Id: PointLight.java 1733416 2016-03-03 07:07:13Z gadams $/**
 * A light source which emits a light of constant intensity in all directions.
 *
 * @author <a href="mailto:vincent.hardy@eng.sun.com">Vincent Hardy</a>
 * @version $Id: PointLight.java 1733416 2016-03-03 07:07:13Z gadams $
 */
public class PointLight extends AbstractLight {
    
The light position, in user space
/**
     * The light position, in user space
     */
    private double lightX, lightY, lightZ;

    
Returns:
the light's x position/**
     * @return the light's x position
     */
    public double getLightX(){
        return lightX;
    }

    
Returns:
the light's y position/**
     * @return the light's y position
     */
    public double getLightY(){
        return lightY;
    }

    
Returns:
the light's z position/**
     * @return the light's z position
     */
    public double getLightZ(){
        return lightZ;
    }

    public PointLight(double lightX, double lightY, double lightZ,
                      Color lightColor){
        super(lightColor);
        this.lightX = lightX;
        this.lightY = lightY;
        this.lightZ = lightZ;
    }

    
Returns:
true if the light is constant over the whole surface/**
     * @return true if the light is constant over the whole surface
     */
    public boolean isConstant(){
        return false;
    }

    
Computes the light vector in (x, y, z)
Params:
x – x-axis coordinate where the light should be computed
y – y-axis coordinate where the light should be computed
z – z-axis coordinate where the light should be computed
L – array of length 3 where the result is stored/**
     * Computes the light vector in (x, y, z)
     *
     * @param x x-axis coordinate where the light should be computed
     * @param y y-axis coordinate where the light should be computed
     * @param z z-axis coordinate where the light should be computed
     * @param L array of length 3 where the result is stored
     */
    public final void getLight(final double x, final double y, final double z,
                               final double[] L){

        double L0 = lightX - x;
        double L1 = lightY - y;
        double L2 = lightZ - z;

        final double norm = Math.sqrt( L0*L0 + L1*L1 + L2*L2 );

        if(norm > 0){
            final double invNorm = 1.0/norm;
            L0 *= invNorm;
            L1 *= invNorm;
            L2 *= invNorm;
        }

        // copy the work-variables into return-array
        L[ 0 ] = L0;
        L[ 1 ] = L1;
        L[ 2 ] = L2;
    }
}