com.ardor3d.math.functions.HexGridFunction3D Maven / Gradle / Ivy

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/**
 * Copyright (c) 2008-2012 Ardor Labs, Inc.
 *
 * This file is part of Ardor3D.
 *
 * Ardor3D is free software: you can redistribute it and/or modify it 
 * under the terms of its license which may be found in the accompanying
 * LICENSE file or at .
 */

package com.ardor3d.math.functions;

import com.ardor3d.math.MathUtils;

/**
 * Creates a hexagon pattern in the XY plane. This is not really 3D, since it ignores the z factor.
 */
public class HexGridFunction3D extends GridPatternFunction3D {

    private static final double EQUILATERAL_TRIANGLE_HEIGHT = Math.sqrt(3.0) / 2.0;

    private static final double[][] FIXED_VALUES = new double[6][6];

    static {
        FIXED_VALUES[0][0] = FIXED_VALUES[5][0] = -1;
        FIXED_VALUES[0][1] = FIXED_VALUES[5][1] = 0;
        FIXED_VALUES[0][2] = FIXED_VALUES[5][2] = 0;
        FIXED_VALUES[0][3] = FIXED_VALUES[5][3] = 1;
        FIXED_VALUES[0][4] = FIXED_VALUES[5][4] = 1;
        FIXED_VALUES[0][5] = FIXED_VALUES[5][5] = -1;

        FIXED_VALUES[2][0] = FIXED_VALUES[3][0] = 1;
        FIXED_VALUES[2][1] = FIXED_VALUES[3][1] = 1;
        FIXED_VALUES[2][2] = FIXED_VALUES[3][2] = -1;
        FIXED_VALUES[2][3] = FIXED_VALUES[3][3] = -1;
        FIXED_VALUES[2][4] = FIXED_VALUES[3][4] = 0;
        FIXED_VALUES[2][5] = FIXED_VALUES[3][5] = 0;

        FIXED_VALUES[1][0] = FIXED_VALUES[4][0] = -1;
        FIXED_VALUES[1][1] = FIXED_VALUES[4][1] = 1;
        FIXED_VALUES[1][2] = FIXED_VALUES[4][2] = 0;
        FIXED_VALUES[1][3] = FIXED_VALUES[4][3] = -1;
        FIXED_VALUES[1][4] = FIXED_VALUES[4][4] = 1;
        FIXED_VALUES[1][5] = FIXED_VALUES[4][5] = 0;
    }

    private static final double[] ALTERNATE_VALUES = { 1, 0, -1, 1, 0, -1 };

    public HexGridFunction3D() {
        super(FIXED_VALUES, 0.5, EQUILATERAL_TRIANGLE_HEIGHT);
    }

    @Override
    protected double getCellValue(final int gridX, final int gridY, final double scaledX, final double scaledY) {
        double value = 0.0;

        switch (gridX) {
            case 0:
            case 2:
            case 3:
            case 5:
                value = super.getCellValue(gridX, gridY, scaledX, scaledY);
                break;
            case 1:
            case 4:
                double x = scaledX - gridX;
                final double y = scaledY - gridY;

                // If a grid block has a negative slope, flip it.
                if (((gridX + gridY) % 2) == 1) {
                    x = 1.0 - x;
                }

                if (x == 0.0) {
                    x = MathUtils.ZERO_TOLERANCE;
                }

                final boolean lowAngle = ((y / x) < 1.0);
                if (lowAngle) {
                    value = super.getCellValue(gridX, gridY, scaledX, scaledY);
                } else {
                    value = ALTERNATE_VALUES[gridY];
                }
                break;
        }

        return value;
    }
}