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/* |
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* This file is part of ArakneUtils. |
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* |
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* ArakneUtils is free software: you can redistribute it and/or modify |
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* it under the terms of the GNU Lesser General Public License as published by |
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* the Free Software Foundation, either version 3 of the License, or |
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* (at your option) any later version. |
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* |
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* ArakneUtils is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public License |
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* along with ArakneUtils. If not, see <https://www.gnu.org/licenses/>. |
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* |
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* Copyright (c) 2017-2021 Vincent Quatrevieux |
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*/ |
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package fr.arakne.utils.maps.sight; |
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import fr.arakne.utils.maps.BattlefieldCell; |
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import fr.arakne.utils.maps.CoordinateCell; |
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import java.util.Iterator; |
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/** |
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* Iterate between cells of the line of sight of two not aligned cells |
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* |
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* @param <C> The cell type |
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*/ |
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final class NotAlignedLineOfSightIterator<C extends BattlefieldCell> implements Iterator<C> { |
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private final BattlefieldSight<C> battlefield; |
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private final CoordinateCell<C> source; |
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private final CoordinateCell<C> target; |
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private final int xDirection; |
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private final int yDirection; |
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private final double ySlope; |
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private final double yAtZero; |
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private int currentX; |
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private int currentY; |
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private int lastY; |
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private int nextY; |
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public NotAlignedLineOfSightIterator(BattlefieldSight<C> battlefield, CoordinateCell<C> source, CoordinateCell<C> target) { |
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this.battlefield = battlefield; |
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this.source = source; |
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this.target = target; |
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this.xDirection = source.x() > target.x() ? -1 : 1; |
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this.yDirection = source.y() > target.y() ? -1 : 1; |
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this.ySlope = (double) (target.y() - source.y()) / (double) (target.x() - source.x()); |
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this.yAtZero = source.y() - ySlope * source.x(); |
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init(); |
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} |
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@Override |
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public boolean hasNext() { |
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return !target.is(currentX, currentY); |
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} |
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@Override |
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public C next() { |
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currentY += yDirection; |
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// lastY is exceeded : increment the X value |
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if (currentY * yDirection > lastY * yDirection) { |
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currentX += xDirection; |
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currentY = nextY; |
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computeNextY(); |
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} |
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return getCurrentCell(); |
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} |
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/** |
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* Initialise iterator |
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*/ |
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private void init() { |
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currentX = source.x(); |
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currentY = source.y(); |
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computeNextY(); |
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} |
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/** |
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* Compute the target Y coordinate for the current X value |
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* The value lastY is used as ending boundary for the Y coordinate iteration |
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* The value nextY is used as start boundary for the Y coordinate iteration for the next X value |
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*/ |
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private void computeNextY() { |
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// yMax is the value of Y at the current X |
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// + 0.5 permit to ignore cells around the line of sight on diagonal (i.e. ySlope = 1) |
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final double yAtCurrentX = (currentX + xDirection * 0.5) * ySlope + yAtZero; |
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if (yDirection > 0) { |
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nextY = (int) Math.round(yAtCurrentX); |
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lastY = (int) Math.ceil(yAtCurrentX - 0.5); |
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} else { |
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nextY = (int) Math.ceil(yAtCurrentX - 0.5); |
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lastY = (int) Math.round(yAtCurrentX); |
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} |
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} |
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/** |
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* @return The cell on the current coordinates |
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*/ |
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private C getCurrentCell() { |
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return battlefield.getCellByCoordinates(currentX, currentY); |
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} |
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} |
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