1/FloatFractal.java

/*
 
File: FloatFractal.java
 
Abstract: This class generates a fractal using the diamond-square method
    implemented recursively.
 
Version: 1.0
 
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*/
 
import java.awt.*;
import java.util.*;
import javax.swing.*;
 
/**
 * Class that generates a new fractal using the diamond-square method implemented in a
 * recursive algorithm.
 *
 * @author Joshua Outwater
 */
public class FloatFractal {
    /** Size of the fractal to generate.  Must be 2^n + 1 */
    private int _gridSize;
    /** Roughness value which creates more dramatic peaks/valleys when increased. */
    private float _fudgeFactor;
    private float[][] _data;
    private Random _random = new Random();
    private float _tmpHeight;
    private int _xDiff;
    private int _yDiff;
    private float _minHeight;
    private float _maxHeight;
 
    /* The range of values contained by this fractal. */
    private float _range;
 
    public FloatFractal(int gridSize, float fudgeFactor) {
        _gridSize = gridSize;
        _fudgeFactor = fudgeFactor;
        _data = new float[_gridSize][_gridSize];
    }
 
    /**
     * Return the 2D data array that contains the fractal data.
     */
    public float[][] getData() {
        return _data;
    }
 
    /**
     * Get the percentage of the range for the specified value in the fractal.
     *
     * @param x column
     * @param y row
     * @return percentage
     */
    public float getPercentageHeight(int x, int y) {
        return (_data[x][y] - _minHeight) / _range;
    }
 
    public float getMaxHeight() {
        return _maxHeight;
    }
 
    public float getMinHeight() {
        return _minHeight;
    }
 
    private void updateMinMaxHeight(float value) {
        if (value > _maxHeight) {
            _maxHeight = value;
        }
 
        if (value < _minHeight) {
            _minHeight = value;
        }
    }
 
    /**
     * Generate a new fractal.
     */
    public void generateFractal() {
        // Initialize the min/max height values.
        _minHeight = Float.MAX_VALUE;
        _maxHeight = Float.MIN_VALUE;
 
        // Initialize the data array.
        for (int x = 0; x < _gridSize; x++) {
            for (int y = 0; y < _gridSize; y++) {
                _data[x][y] = Float.MIN_VALUE;
            }
        }
 
        seedRecursiveData();
 
        recursiveGenerateFractal(new Point(0, 0),
                new Point(0, _gridSize - 1),
                new Point(_gridSize - 1, 0),
                new Point(_gridSize - 1, _gridSize - 1), _fudgeFactor);
 
        // Calculate the range of values.
        _range = _maxHeight - _minHeight;
    }
 
    /**
     * Seed the four corners of the data map so we can generate a fractal.
     */
    private void seedRecursiveData() {
        _data[0][0] = (_random.nextFloat() % _fudgeFactor) *
                (_random.nextBoolean() ? 1 : -1);
        _data[0][_gridSize - 1] = (_random.nextFloat() % _fudgeFactor) *
                (_random.nextBoolean() ? 1 : -1);
        _data[_gridSize - 1][0] = (_random.nextFloat() % _fudgeFactor) *
                (_random.nextBoolean() ? 1 : -1);
        _data[_gridSize - 1][_gridSize - 1] = (_random.nextFloat() % _fudgeFactor) *
                (_random.nextBoolean() ? 1 : -1);
        updateMinMaxHeight(_data[0][0]);
        updateMinMaxHeight(_data[0][_gridSize - 1]);
        updateMinMaxHeight(_data[_gridSize - 1][0]);
        updateMinMaxHeight(_data[_gridSize - 1][_gridSize - 1]);
    }
 
    /**
     * Recursive algorithm that generates a fractal using the diamond-square method.
     */
    private void recursiveGenerateFractal(Point topLeft, Point bottomLeft,
            Point bottomRight, Point topRight, float fudgeFactor) {
 
        /**
         * Diamond step:
         *  Use the four points defining this square to calculate the value at the center.
         *  The center point is determined by averaging the square's edge values plus a random
         *  value.  By adding this new center point we have now created four diamonds.
         */
        // Calculate the midpoint of the square.
        Point midPoint = new Point((topLeft.x + topRight.x) / 2,
                (topLeft.y + bottomLeft.y) / 2) ;
 
        // Exit case.
        if (midPoint.equals(topLeft)) {
            return;
        }
 
        // Calculate the height of this new point.
        _tmpHeight = (_data[topLeft.x][topLeft.y] +
                _data[bottomLeft.x][bottomLeft.y] +
                _data[bottomRight.x][bottomRight.y] +
                _data[topRight.x][topRight.y]) / 4;
        _tmpHeight += (_random.nextFloat() % fudgeFactor) * (_random.nextBoolean() ? 1 : -1);
        _data[midPoint.x][midPoint.y] = _tmpHeight;
        updateMinMaxHeight(_data[midPoint.x][midPoint.y]);
 
        /**
         * Square step:
         *  Use the four points defining the diamonds to calculate the value at the center.  The
         *  center point is determined by averaging the diamond's edge values plus a random value.
         *  By adding these new center points to the diamonds we have now returned the grid to
         *  squares.
         */
        // Calculate the offscreen diamond point for the topMid if it wasn't calculated already.
        Point topMid = new Point((topLeft.x + topRight.x) / 2, topLeft.y);
        if (_data[topMid.x][topMid.y] == Float.MIN_VALUE) {
            _yDiff = midPoint.y - topMid.y;
            _tmpHeight = Float.MIN_VALUE;
            if (topMid.y - _yDiff >= 0) {
                _tmpHeight = _data[topMid.x][topMid.y - _yDiff];
            }
            // Calculate the height of this new point.
            _data[topMid.x][topMid.y] = ((_tmpHeight != Float.MIN_VALUE ? _tmpHeight : 0) +
                    _data[topLeft.x][topLeft.y] +
                    _data[midPoint.x][midPoint.y] +
                    _data[topRight.x][topRight.y]) /
                        (_tmpHeight != Float.MIN_VALUE ? 4 : 3);
            _data[topMid.x][topMid.y] += (_random.nextFloat() % fudgeFactor) *
                    (_random.nextBoolean() ? 1 : -1);
            updateMinMaxHeight(_data[topMid.x][topMid.y]);
        }
 
        // Calculate the offscreen diamond point for the midLeft if it wasn't calucaulted already.
        Point midLeft = new Point(topLeft.x , (topLeft.y + bottomLeft.y) / 2);
        if (_data[midLeft.x][midLeft.y] == Float.MIN_VALUE) {
            _xDiff = midPoint.x - midLeft.x;
            _tmpHeight = Float.MIN_VALUE;
            if (midLeft.x - _xDiff >= 0) {
                _tmpHeight = _data[midLeft.x - _xDiff][midLeft.y];
            }
            // Calculate the height of this new point.
            _data[midLeft.x][midLeft.y] = (_data[topLeft.x][topLeft.y] +
                    (_tmpHeight != Float.MIN_VALUE ? _tmpHeight : 0) +
                    _data[bottomLeft.x][bottomLeft.y] +
                    _data[midPoint.x][midPoint.y]) /
                        (_tmpHeight != Float.MIN_VALUE ? 4 : 3);
            _data[midLeft.x][midLeft.y] += (_random.nextFloat() % fudgeFactor) *
                    (_random.nextBoolean() ? 1 : -1);
            updateMinMaxHeight(_data[midLeft.x][midLeft.y]);
        }
 
        // Calculate the offscreen diamond point for the bottomMid if it wasn't calucaulted already.
        Point bottomMid = new Point((bottomLeft.x + bottomRight.x) / 2, bottomLeft.y);
        if (_data[bottomMid.x][bottomMid.y] == Float.MIN_VALUE) {
            _yDiff = bottomMid.y - midPoint.y;
            _tmpHeight = Float.MIN_VALUE;
            if (bottomMid.y + _yDiff < _gridSize) {
                _tmpHeight = _data[bottomMid.x][bottomMid.y + _yDiff];
            }
            // Calculate the height of this new point.
            _data[bottomMid.x][bottomMid.y] = (_data[midPoint.x][midPoint.y] +
                    _data[bottomLeft.x][bottomLeft.y] +
                    (_tmpHeight != Float.MIN_VALUE ? _tmpHeight : 0) +
                    _data[bottomRight.x][bottomRight.y]) /
                        (_tmpHeight != Float.MIN_VALUE ? 4 : 3);
            _data[bottomMid.x][bottomMid.y] += (_random.nextFloat() % fudgeFactor) *
                    (_random.nextBoolean() ? 1 : -1);
            updateMinMaxHeight(_data[bottomMid.x][bottomMid.y]);
        }
 
        // Calculate the offscreen diamond point for the midRight.
        Point midRight = new Point(topRight.x, (topRight.y + bottomRight.y) / 2);
        if (_data[midRight.x][midRight.y] == Float.MIN_VALUE) {
            _xDiff = midRight.x - midPoint.x;
            _tmpHeight = Float.MIN_VALUE;
            if (midRight.x + _xDiff < _gridSize) {
                _tmpHeight = _data[midRight.x + _xDiff][midRight.y];
            }
            // Calculate the height of this new point.
            _data[midRight.x][midRight.y] = (_data[topRight.x][topRight.y] +
                    _data[midPoint.x][midPoint.y] +
                    _data[bottomRight.x][bottomRight.y] + 
                    (_tmpHeight != Float.MIN_VALUE ? _tmpHeight : 0)) /
                        (_tmpHeight != Float.MIN_VALUE ? 4 : 3);
            _data[midRight.x][midRight.y] += (_random.nextFloat() % fudgeFactor) *
                    (_random.nextBoolean() ? 1 : -1);
            updateMinMaxHeight(_data[midRight.x][midRight.y]);
        }
 
        // Halve the height for next round.
        fudgeFactor /= 2;
 
        // Generate fractal data for each new square.
        recursiveGenerateFractal(topLeft, midLeft, midPoint, topMid, fudgeFactor);
        recursiveGenerateFractal(midLeft, bottomLeft, bottomMid, midPoint, fudgeFactor);
        recursiveGenerateFractal(midPoint, bottomMid, bottomRight, midRight, fudgeFactor);
        recursiveGenerateFractal(topMid, midPoint, midRight, topRight, fudgeFactor);
    }
 
    public String toString() {
        StringBuffer strBuf = new StringBuffer();
        for (int x = 0; x < _gridSize; x++) {
            for (int y = 0; y < _gridSize; y++) {
                strBuf.append(_data[x][y] + " ");
            }
            strBuf.append("\n");
        }
        return strBuf.toString();
    }
}


© 2006 Apple Computer, Inc. All Rights Reserved. (Last updated: 2006-04-17)

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