org.jtrfp.trcl.InterpolatingAltitudeMap.java Source code

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Here is the source code for org.jtrfp.trcl.InterpolatingAltitudeMap.java

Source

/*******************************************************************************
 * This file is part of TERMINAL RECALL
 * Copyright (c) 2012-2014 Chuck Ritola
 * Part of the jTRFP.org project
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the GNU Public License v3.0
 * which accompanies this distribution, and is available at
 * http://www.gnu.org/licenses/gpl.html
 * 
 * Contributors:
 *     chuck - initial API and implementation
 ******************************************************************************/
package org.jtrfp.trcl;

import org.apache.commons.math3.geometry.euclidean.threed.Vector3D;

public class InterpolatingAltitudeMap implements AltitudeMap {
    private AltitudeMap toWrap;
    private double NUDGE = .25;

    public InterpolatingAltitudeMap(AltitudeMap toWrap) {
        this.toWrap = toWrap;
    }

    @Override
    public double heightAt(double x, double z) {
        final int xLow = (int) Math.floor(x);
        final int xHi = (int) Math.ceil(x);
        final int zLow = (int) Math.floor(z);
        final int zHi = (int) Math.ceil(z);
        final double topLeft = toWrap.heightAt(xLow, zLow);
        final double topRight = toWrap.heightAt(xHi, zLow);
        final double bottomLeft = toWrap.heightAt(xLow, zHi);
        final double bottomRight = toWrap.heightAt(xHi, zHi);
        final double wRight = x - xLow;
        final double wLeft = 1. - wRight;
        final double wBottom = z - zLow;
        final double wTop = 1. - wBottom;
        double accumulator = 0;
        accumulator += topLeft * wTop * wLeft;
        accumulator += topRight * wTop * wRight;
        accumulator += bottomLeft * wBottom * wLeft;
        accumulator += bottomRight * wBottom * wRight;
        return accumulator;
    }

    @Override
    public double getWidth() {
        return toWrap.getWidth();
    }

    @Override
    public double getHeight() {
        return toWrap.getHeight();
    }

    public Vector3D normalAt(double x, double z) {
        final double magX = (heightAt(x - NUDGE, z) - heightAt(x + NUDGE, z)) / NUDGE;
        final double magZ = (heightAt(x, z - NUDGE) - heightAt(x, z + NUDGE)) / NUDGE;
        final double magY = Math.sqrt(1 - (magX * magX + magZ * magZ));
        return new Vector3D(magX, magY, magZ).normalize();
    }//end normalAt(...)
}//end InterpolatingAltitudeMap