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Noise generation library for Java, based on the libnoise C++ library.
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/*
 * This file is part of Flow Noise, licensed under the MIT License (MIT).
 *
 * Copyright (c) 2013 Flow Powered 
 * Original libnoise in C++ by Jason Bevins 
 * jlibnoise Java port by Garrett Fleenor 
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package com.flowpowered.noise.model;

import com.flowpowered.noise.exception.NoModuleException;
import com.flowpowered.noise.module.Module;

/**
 * Model that defines the displacement of a line segment.
 * 
 * This model returns an output value from a noise module given the one-dimensional coordinate of an input value located on a line segment, which can be used as displacements.
 * 

 * This class is useful for creating: - roads and rivers - disaffected college students
 * 

 * To generate an output value, pass an input value between 0.0 and 1.0 to the GetValue() method. 0.0 represents the start position of the line segment and 1.0 represents the end position of the line
 * segment.
 */
public class Line {
    // A flag that specifies whether the value is to be attenuated
    // (moved toward 0.0) as the ends of the line segment are approached.
    private boolean attenuate = false;
    // A pointer to the noise module used to generate the output values.
    private Module module;
    // @a x coordinate of the start of the line segment.
    private double x0 = 0;
    // @a x coordinate of the end of the line segment.
    private double x1 = 1;
    // @a y coordinate of the start of the line segment.
    private double y0 = 0;
    // @a y coordinate of the end of the line segment.
    private double y1 = 1;
    // @a z coordinate of the start of the line segment.
    private double z0 = 0;
    // @a z coordinate of the end of the line segment.
    private double z1 = 1;

    /**
     * @param module The noise module that is used to generate the output values.
     */
    public Line(Module module) {
        if (module == null) {
            throw new IllegalArgumentException("module cannot be null");
        }
        this.module = module;
    }

    /**
     * Returns a flag indicating whether the output value is to be attenuated (moved toward 0.0) as the ends of the line segment are approached by the input value.
     *
     * @return true if the value is to be attenuated false if not.
     */
    public boolean attenuate() {
        return this.attenuate;
    }

    /**
     * Sets a flag indicating that the output value is to be attenuated (moved toward 0.0) as the ends of the line segment are approached.
     *
     * @param att A flag that specifies whether the output value is to be attenuated.
     */
    public void setAttenuate(boolean att) {
        this.attenuate = att;
    }

    /**
     * Sets the position ( @a x, @a y, @a z ) of the start of the line segment to choose values along.
     *
     * @param x x coordinate of the start position.
     * @param y y coordinate of the start position.
     * @param z z coordinate of the start position.
     */
    public void setStartPoint(double x, double y, double z) {
        this.x0 = x;
        this.y0 = y;
        this.z0 = z;
    }

    /**
     * Sets the position ( @a x, @a y, @a z ) of the end of the line segment to choose values along.
     *
     * @param x x coordinate of the end position.
     * @param y y coordinate of the end position.
     * @param z z coordinate of the end position.
     */
    public void setEndPoint(double x, double y, double z) {
        this.x1 = x;
        this.y1 = y;
        this.z1 = z;
    }

    /**
     * Returns the noise module that is used to generate the output values.
     */
    public Module getModule() {
        return module;
    }

    /**
     * Sets the noise module that is used to generate the output values.
     *
     * @param module The noise module that is used to generate the output values.
     * 
     * This noise module must exist for the lifetime of this object, until you pass a new noise module to this method.
     */
    public void setModule(Module module) {
        if (module == null) {
            throw new IllegalArgumentException("module cannot be null");
        }
        this.module = module;
    }

    /**
     * Returns the output value from the noise module given the one-dimensional coordinate of the specified input value located on the line segment.
     *
     * @param p The distance along the line segment (ranges from 0.0 to 1.0)
     * @return The output value from the noise module.
     */
    public double getValue(double p) {
        if (module == null) {
            throw new NoModuleException();
        }

        double x = (x1 - x0) * p + x0;
        double y = (y1 - y0) * p + y0;
        double z = (z1 - z0) * p + z0;
        double value = module.getValue(x, y, z);

        if (attenuate) {
            return p * (1.0 - p) * 4 * value;
        } else {
            return value;
        }
    }
}