Examples:SpaceInvaders AlienEntity

 /* * Copyright (c) 2002-2010 LWJGL Project * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are * met: * * * Redistributions of source code must retain the above copyright *  notice, this list of conditions and the following disclaimer. * * * Redistributions in binary form must reproduce the above copyright *  notice, this list of conditions and the following disclaimer in the *  documentation and/or other materials provided with the distribution. * * * Neither the name of 'LWJGL' nor the names of *   its contributors may be used to endorse or promote products derived *  from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ package org.lwjgl.examples.spaceinvaders;

/** * An entity which represents one of our space invader aliens. * * @author Kevin Glass * @author Brian Matzon */ public class AlienEntity extends Entity {

/** Movement made downwards when a border is hit */ private static final int	DOWNWARD_MOVEMENT	= 10;

/** Border at which player dies */ private static final int	BOTTOM_BORDER			= 570;

/** Right border at which to shift direction */ private static final int	RIGHT_BORDER			= 750;

/** Left border at which to shift direction */ private static final int	LEFT_BORDER				= 10;

/** The speed at which the alient moves horizontally */ private float							moveSpeed					= 75;

/** The game in which the entity exists */ private Game							game;

/** The animation frames */ private Sprite[]					frames						= new Sprite[4];

/** The time since the last frame change took place */ private long							lastFrameChange;

/** The frame duration in milliseconds, i.e. how long any given frame of animation lasts */ private long							frameDuration			= 250;

/** The current frame of animation being displayed */ private int								frameNumber;

/**	 * Create a new alien entity * 	 * @param game The game in which this entity is being created * @param x The intial x location of this alien * @param y The intial y location of this alient */	public AlienEntity(Game game, int x, int y) { super(game.getSprite("alien.gif"), x, y);

// setup the animatin frames frames[0] = sprite; frames[1] = game.getSprite("alien2.gif"); frames[2] = sprite; frames[3] = game.getSprite("alien3.gif");

this.game = game; dx = -moveSpeed; }

/**	 * Request that this alien moved based on time elapsed * 	 * @param delta The time that has elapsed since last move */	public void move(long delta) { // since the move tells us how much time has passed // by we can use it to drive the animation, however // its the not the prettiest solution lastFrameChange += delta;

// if we need to change the frame, update the frame number // and flip over the sprite in use if (lastFrameChange > frameDuration) { // reset our frame change time counter lastFrameChange = 0;

// update the frame frameNumber++; if (frameNumber >= frames.length) { frameNumber = 0; }

sprite = frames[frameNumber]; }

// if we have reached the left hand side of the screen and // are moving left then request a logic update if ((dx < 0) && (x < LEFT_BORDER)) { game.updateLogic; }		// and vice vesa, if we have reached the right hand side of 		// the screen and are moving right, request a logic update if ((dx > 0) && (x > RIGHT_BORDER)) { game.updateLogic; }

// proceed with normal move super.move(delta); }

/**	 * Update the game logic related to aliens */	public void doLogic { // swap over horizontal movement and move down the // screen a bit dx = -dx; y += DOWNWARD_MOVEMENT;

// if we've reached the bottom of the screen then the player // dies if (y > BOTTOM_BORDER) { game.notifyDeath; }	}

/**	 * Notification that this alien has collided with another entity * 	 * @param other The other entity */	public void collidedWith(Entity other) { // collisions with aliens are handled elsewhere } }