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 * Copyright (c) 2007 Sun Microsystems, Inc. All Rights Reserved.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
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package net.java.joglutils.msg.elements;

import javax.media.opengl.*;

import net.java.joglutils.msg.math.*;
import net.java.joglutils.msg.misc.*;
import net.java.joglutils.msg.nodes.*;

/** Represents the depth test state of the OpenGL fixed-function pipeline. */

public class DepthTestElement extends Element {

  // Boilerplate
  private static StateIndex index = State.registerElementType();
  public StateIndex getStateIndex() { return index; }
  public Element newInstance() {
    return new DepthTestElement();
  }
  /** Returns the instance of this element in the passed State. */
  public static DepthTestElement getInstance(State state) {
    return (DepthTestElement) state.getElement(index);
  }
  /** Enables this element in the passed state, which should be the
      default for a given action. */
  public static void enable(State defaultState) {
    DepthTestElement tmp = new DepthTestElement();
    defaultState.setElement(tmp.getStateIndex(), tmp);
  }
  /** Indicates whether this element is enabled in the given default
      state for a particular action. */
  public static boolean isEnabled(State state) {
    return (state.getDefaults().getElement(index) != null);
  }

  // TODO: eventually we'll want to add other state associated with
  // depth testing, such as the the depth function and values
  protected boolean enabled;

  /** Sets the depth test state. */
  public static void set(State state, boolean enabled) {
    getInstance(state).setElt(enabled);
  }

  /** Returns whether depth testing is enabled. */
  public static boolean getEnabled(State state) {
    return getInstance(state).enabled;
  }

  public void push(State state) {
    DepthTestElement prev = (DepthTestElement) getNextInStack();
    if (prev != null) {
      // Pull down the data from the previous element
      enabled = prev.enabled;
    }
  }

  /** Sets all of the portions of the depth test state in this element. */
  public void setElt(boolean enabled) {
    this.enabled = enabled;
  }
}