PhysicsShapeBuilderStrategyRectangle.java

/*
 * Catroid: An on-device visual programming system for Android devices
 * Copyright (C) 2010-2016 The Catrobat Team
 * (<http://developer.catrobat.org/credits>)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * An additional term exception under section 7 of the GNU Affero
 * General Public License, version 3, is available at
 * http://developer.catrobat.org/license_additional_term
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.catrobat.catroid.physics.shapebuilder;

import android.graphics.Point;

import com.badlogic.gdx.graphics.Pixmap;
import com.badlogic.gdx.math.Vector2;
import com.badlogic.gdx.physics.box2d.PolygonShape;
import com.badlogic.gdx.physics.box2d.Shape;

import org.catrobat.catroid.physics.PhysicsWorldConverter;

public class PhysicsShapeBuilderStrategyRectangle implements PhysicsShapeBuilderStrategy {

	@Override
	public Shape[] build(Pixmap pixmap, float scale) {

		if (pixmap == null) {
			return null;
		}

		Point start = null;
		Point end = null;

		for (int y = 0; y < pixmap.getHeight(); y++) {
			for (int x = 0; x < pixmap.getWidth(); x++) {
				int alpha = pixmap.getPixel(x, y) & 0xff;

				if (alpha > 0) {
					if (start == null) {
						start = new Point(x, y);
						end = new Point(x, y);
						continue;
					}

					if (x < start.x) {
						start.x = x;
					} else if (x > end.x) {
						end.x = x;
					}

					if (y < start.y) {
						start.y = y;
					} else if (y > end.y) {
						end.y = y;
					}
				}
			}
		}

		if (start == null) {
			return null;
		}

		int width = end.x - start.x;
		int height = end.y - start.y;

		if (width == 0) {
			width = 1;
		}

		if (height == 0) {
			height = 1;
		}

		float box2dWidth = PhysicsWorldConverter.convertNormalToBox2dCoordinate(width) / 2.0f;
		float box2dHeight = PhysicsWorldConverter.convertNormalToBox2dCoordinate(height) / 2.0f;
		Vector2 center = new Vector2(box2dWidth
				- PhysicsWorldConverter.convertNormalToBox2dCoordinate(pixmap.getWidth() / 2.0f), box2dHeight
				- PhysicsWorldConverter.convertNormalToBox2dCoordinate(pixmap.getHeight() / 2.0f));
		PolygonShape polygonShape = new PolygonShape();
		polygonShape.setAsBox(box2dWidth, box2dHeight, center, 0.0f);

		return new Shape[] { polygonShape };
	}
}