switchnode.java

来自「java 3d game jme 工程开发源代码」· Java 代码 · 共 213 行

/*
 * 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.jme.scene;

import java.io.IOException;

import com.jme.intersection.CollisionResults;
import com.jme.intersection.PickResults;
import com.jme.math.Ray;
import com.jme.renderer.Renderer;
import com.jme.util.export.InputCapsule;
import com.jme.util.export.JMEExporter;
import com.jme.util.export.JMEImporter;
import com.jme.util.export.OutputCapsule;

/**
 * <code>SwitchNode</code> defines a node that maintains a single active child
 * at a time. This allows the instantanious switching of children depending on
 * any number of factors. For example, multiple levels of detail models can be
 * loaded into the switch node and the active model can be set depending on the
 * distance from the camera.
 * 
 * @author Mark Powell
 * @version $Id: SwitchNode.java,v 1.11 2006/09/29 22:36:52 nca Exp $
 */
public class SwitchNode extends Node {
	private static final long serialVersionUID = 1L;

	/**
	 * defines an inactive or invalid child.
	 */
	public static final int SN_INVALID_CHILD = -1;

	private int activeChild;

	private Spatial activeChildData;

    public SwitchNode() {}
    
	/**
	 * Constructor instantiates a new <code>SwitchNode</code> object. The name
	 * of the node is provided during construction.
	 * 
	 * @param name
	 *            the name of the node.
	 */
	public SwitchNode(String name) {
		super(name);
		activeChild = SN_INVALID_CHILD;
	}

	/**
	 * Returns the index of the currently rendered child for this Node.
	 * 
	 * @return The currently active child.
	 */
	public int getActiveChild() {
		return activeChild;
	}

	/**
	 * Sets the index of the child of this Node that will be rendered. If the
	 * index is <0 or >getQuantity then nothing is rendered.
	 * 
	 * @param child
	 *            The child index of this node it should render.
	 */
	public void setActiveChild(int child) {
		if (child < 0 || child > getQuantity()) {
			activeChild = SN_INVALID_CHILD;
		} else {
            if(activeChildData != null) {
                activeChildData.setIsCollidable(false);
            }
            this.activeChild = child;
			activeChildData = getChild(activeChild);
            activeChildData.setIsCollidable(true);
		}
   }

	/**
	 * Marks the node to render nothing on a draw.
	 */
	public void disableAllChildren() {
		activeChild = SN_INVALID_CHILD;
	}
    
    /**
     * Attaches a child to this SwitchNode. This child will not be visible unless
     * it is set to the active child. It should be noted that the attachment of
     * the child will set it to be non-collidable. Only active child are collidable
     * using a SwitchNode.
     */
    @Override
    public int attachChild(Spatial child) {
        child.setIsCollidable(false);
        return super.attachChild(child);
    }
    
    /**
     * Attaches a child to this SwitchNode at a specified index. This child will not be visible unless
     * it is set to the active child. It should be noted that the attachment of
     * the child will set it to be non-collidable. Only active child are collidable
     * using a SwitchNode.
     */
    @Override
    public int attachChildAt(Spatial child, int index) {
        child.setIsCollidable(false);
        return super.attachChildAt(child, index);
    }

	/**
	 * If a valid active child is set, that child is rendered and none others.
	 * This function should be called internally only.
	 * 
	 * @param r
	 *            The render system to draw the child.
	 */
    @Override
	public void draw(Renderer r) {
		if (activeChild != SN_INVALID_CHILD) {
			if (activeChildData != null) {
				activeChildData.onDraw(r);
			}
		}
	}
    
    /**
     * collisions are checked for the currently active child.
     */
    @Override
    public void findCollisions(Spatial scene, CollisionResults results) {
        if (this == scene || !isCollidable || !scene.isCollidable()) {
            return;
        }

        if (activeChild != SN_INVALID_CHILD) {
            if (activeChildData != null) {
                activeChildData.findCollisions(scene, results);
            }
        }
    }
    
    /**
     * collisions are checked for the currently active child.
     */
    @Override
    public boolean hasCollision(Spatial scene, boolean checkTriangles) {
        if (this == scene || !isCollidable || !scene.isCollidable()) {
            return false;
        }

        if (activeChild != SN_INVALID_CHILD) {
            if (activeChildData != null) {
                return activeChildData.hasCollision(scene, checkTriangles);
            }
        }
        return false;
    }
    
    public void findPick(Ray toTest, PickResults results) {
        if (activeChild != SN_INVALID_CHILD) {
            if (activeChildData != null) {
                activeChildData.findPick(toTest, results);
            }
        }
    }
    
    
    public void write(JMEExporter e) throws IOException {
        super.write(e);
        OutputCapsule capsule = e.getCapsule(this);
        capsule.write(activeChild, "activeChild", 0);
        capsule.write(activeChildData, "activeChildData", null);
    }

    public void read(JMEImporter e) throws IOException {
        super.read(e);
        InputCapsule capsule = e.getCapsule(this);
        activeChild = capsule.readInt("activeChild", 0);
        activeChildData = (Spatial)capsule.readSavable("activeChildData", null);
    }
}