gamestate.java

java 3d game jme 工程开发源代码

/*
 * Copyright (c) 2003-2009 jMonkeyEngine
 * 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 'jMonkeyEngine' 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 com.jmex.game.state;

/**
 * A GameState is used to encapsulate a certain state of a game, e.g. "ingame" or
 * "main menu".
 * <p>
 * A GameState can be attached to a GameStateNode, forming a tree structure 
 * similar to jME's scenegraph.
 * <p>
 * It contains two important methods: update(float) and render(float),
 * which gets called by the parent GameStateNode, e.g. the GameStateManager.
 * 
 * @see GameStateManager
 * @see GameStateNode
 * @see BasicGameState
 * @see CameraGameState
 * 
 * @author Per Thulin
 */
public abstract class GameState {
	
	/** The name of this GameState. */
	protected String name;
	
	/** Flags whether or not this GameState should be processed. */
	protected boolean active; 
	
	/** GameState's parent, or null if it has none (is the root node). */
	protected GameStateNode parent;
	
	/**
	 * Gets called every frame before render(float) by the parent 
	 * <code>GameStateNode</code>.
	 * 
	 * @param tpf The elapsed time since last frame.
	 */
    public abstract void update(float tpf);
    
	/**
	 * Gets called every frame after update(float) by the 
	 * <code>GameStateManager</code>.
	 * 
	 * @param tpf The elapsed time since last frame.
	 */
    public abstract void render(float tpf);
    
    /**
     * Gets performed when cleanup is called on a parent GameStateNode (e.g.
     * the GameStateManager).
     */
    public abstract void cleanup();
    
    /**
     * Sets whether or not you want this GameState to be updated and rendered.
     * 
     * @param active 
     *        Whether or not you want this GameState to be updated and rendered.
     */
	public void setActive(boolean active) {
		this.active = active;
	}

    /**
     * Returns whether or not this GameState is updated and rendered.
     * 
     * @return Whether or not this GameState is updated and rendered.
     */
	public boolean isActive() {
		return active;
	}

    /**
     * Returns the name of this GameState.
     * 
     * @return The name of this GameState.
     */
	public String getName() {
		return name;
	}
	
	/**
	 * Sets the name of this GameState.
	 * 
	 * @param name The new name of this GameState.
	 */
	public void setName(String name) {
		this.name = name;
	}
	
	/**
	 * Sets the parent of this node. <b>The user should never touch this method,
	 * instead use the attachChild method of the wanted parent.</b>
	 * 
	 * @param parent The parent of this GameState.
	 */
	public void setParent(GameStateNode parent) {
		this.parent = parent;
	}
	
	/**
	 * Retrieves the parent of this GameState. If the parent is null, this is
	 * the root node.
	 * 
	 * @return The parent of this node.
	 */
	public GameStateNode getParent() {
		return parent;
	}
    
}