PSweepAndPrune.java

/**
 * Copyright 2013 The Loon Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package loon.physics;

import loon.utils.CollectionUtils;

public class PSweepAndPrune {

	boolean checkX;
	int numObject;
	private PSortableObject[] objsX;
	private PSortableObject[] objsY;

	public PSweepAndPrune() {
		objsX = new PSortableObject[1024];
		objsY = new PSortableObject[1024];
	}

	void addObject(PSortableObject ox, PSortableObject oy) {
		if (numObject + 1 >= objsX.length) {
			objsX =  CollectionUtils.copyOf(objsX,
					objsX.length * 2);
			objsY =  CollectionUtils.copyOf(objsY,
					objsY.length * 2);
		}
		objsX[numObject] = ox;
		objsY[numObject] = oy;
		numObject++;
	}

	void removeObject(PSortableObject ox, PSortableObject oy) {
		int indexX = -1;
		int indexY = -1;
		for (int i = 0; i < numObject; i++) {
			if (objsX[i] != ox)
				continue;
			indexX = i;
			break;
		}

		if (indexX != -1 && indexX != numObject - 1)
			System.arraycopy(objsX, indexX + 1, objsX, indexX, numObject
					- indexX - 1);
		for (int i = 0; i < numObject; i++) {
			if (objsY[i] != oy)
				continue;
			indexY = i;
			break;
		}

		if (indexY != -1 && indexY != numObject - 1)
			System.arraycopy(objsY, indexY + 1, objsY, indexY, numObject
					- indexY - 1);
		numObject--;
	}

	PSortableObject[] sort() {
		PInsertionSorter.sort(objsX, numObject);
		PInsertionSorter.sort(objsY, numObject);
		int stack = 0;
		int overlapX = 0;
		int overlapY = 0;
		for (int i = 0; i < numObject; i++)
			if (objsX[i].begin) {
				stack++;
				overlapX += stack;
			} else {
				stack--;
			}

		stack = 0;
		for (int i = 0; i < numObject; i++)
			if (objsY[i].begin) {
				stack++;
				overlapY += stack;
			} else {
				stack--;
			}

		return (checkX = overlapX < overlapY) ? objsX : objsY;
	}

}