Java tutorial
/* * Copyright 1997-2008 Sun Microsystems, Inc. All Rights Reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Sun designates this * particular file as subject to the "Classpath" exception as provided * by Sun in the LICENSE file that accompanied this code. * * This code 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 General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. * */ package javax.media.j3d; /** * Class specifying a wakeup when a specific number of frames have * elapsed. The wakeup criterion can either be passive or * non-passive. If any behavior uses a non-passive * WakeupOnElapsedFrames, the rendering system will run continuously. * * <p> * In general, applications cannot count on behavior execution being * synchronized with rendering. Behaviors that use * WakeupOnElapsedFrames with a frame count of 0 are an exception to * this general rule. Such behaviors will be executed every frame. * Further, all modifications to scene graph objects (not including * geometry by-reference or texture by-reference) made from the * <code>processStimulus</code> methods of such behaviors are * guaranteed to take effect in the same rendering frame. */ public final class WakeupOnElapsedFrames extends WakeupCriterion { // different types of WakeupIndexedList that use in BehaviorStructure static final int COND_IN_BS_LIST = 0; // total number of different IndexedUnorderedSet types static final int TOTAL_INDEXED_UNORDER_SET_TYPES = 1; // Indicates whether the wakeup condition is passive or // non-passive. Only behaviors using a non-passive // WakeupOnElapsedFrames will force a continuous traversal. boolean passive; // Number of frames before wakeup int frameCount; // When this reaches 0, this criterion is met. int countdown; /** * Constructs a non-passive WakeupOnElapsedFrames criterion. * * @param frameCount the number of frames that Java 3D should draw * before awakening this behavior object; a value of N means * wakeup at the end of frame N, where the current frame is zero, * a value of zero means wakeup at the end of the current frame. * * @exception IllegalArgumentException if frameCount is less than zero */ public WakeupOnElapsedFrames(int frameCount) { this(frameCount, false); } /** * Constructs a WakeupOnElapsedFrames criterion. * * @param frameCount the number of frames that Java 3D should draw * before awakening this behavior object; a value of N means * wakeup at the end of frame N, where the current frame is zero, * a value of zero means wakeup at the end of the current frame. * * @param passive flag indicating whether this behavior is * passive; a non-passive behavior will cause the rendering system * to run continuously, while a passive behavior will only run * when some other event causes a frame to be run. * * @exception IllegalArgumentException if frameCount is less than zero * * @since Java 3D 1.2 */ public WakeupOnElapsedFrames(int frameCount, boolean passive) { if (frameCount < 0) throw new IllegalArgumentException(J3dI18N.getString("WakeupOnElapsedFrames0")); this.frameCount = frameCount; this.passive = passive; WakeupIndexedList.init(this, TOTAL_INDEXED_UNORDER_SET_TYPES); } /** * Retrieves the elapsed frame count that was used when * constructing this object. * * @return the elapsed frame count specified when constructing * this object */ public int getElapsedFrameCount() { return frameCount; } /** * Retrieves the state of the passive flag that was used when * constructing this object. * * @return true if this wakeup criterion is passive, false otherwise * * @since Java 3D 1.2 */ public boolean isPassive() { return passive; } /** * decrement the frame count, and set trigger if 0 */ void newFrame() { if (this.countdown == 0) { this.setTriggered(); } else { this.countdown--; } } /** * This is a callback from BehaviorStructure. It is * used to add wakeupCondition to behavior structure. */ @Override void addBehaviorCondition(BehaviorStructure bs) { this.countdown = this.frameCount; bs.wakeupOnElapsedFrames.add(this); if (!passive && (behav != null) && behav.enable) { bs.activeWakeupOnFrameCount++; } // This is necessary to invoke this condition next time // Otherwise jftc won't work for static scene. VirtualUniverse.mc.sendRunMessage(bs.universe, J3dThread.UPDATE_BEHAVIOR); } /** * This is a callback from BehaviorStructure. It is * used to remove wakeupCondition from behavior structure. */ @Override void removeBehaviorCondition(BehaviorStructure bs) { bs.wakeupOnElapsedFrames.remove(this); if (!passive && (behav != null) && behav.enable) { bs.activeWakeupOnFrameCount--; } } /** * Perform task in addBehaviorCondition() that has to be * set every time the condition met. */ @Override void resetBehaviorCondition(BehaviorStructure bs) { this.countdown = this.frameCount; } }