viewingplatform.java

JAVA3D矩陈的相关类

    /**
     * Returns a reference to the "bottom most" transform in the
     * MultiTransformGroup that is above the ViewPlatform node.
     *
     * @return The TransformGroup that is immediately above the
     *  ViewPlatform object.
     */
    public TransformGroup getViewPlatformTransform() {
        return mtg.getTransformGroup(mtg.getNumTransforms() - 1);
    }

    /**
     * Sets the nominal viewing distance in the ViewPlatform transform based
     * on the current field of view.  If the ViewAttachPolicy is not the
     * default of View.NOMINAL_HEAD, then this method has no effect.<p>
     * 
     * The ViewPlatform is moved back along Z so that objects at the origin
     * spanning the normalized X range of -1.0 to +1.0 can be fully viewed
     * across the width of the window.  This is done by setting a translation
     * of 1/(tan(fieldOfView/2)) in the ViewPlatform transform.<p>
     *
     * If there is no Viewer object associated with this ViewingPlatform
     * object the default field of view of PI/4.0 is used.<p>
     * 
     * NOTE: Support for multiple Viewer objects is not available.  If
     * multiple viewers are attached to this ViewingPlatform than a
     * RuntimeException will be thrown.
     */
    public void setNominalViewingTransform() {
	if (viewPlatform.getViewAttachPolicy() == View.NOMINAL_HEAD) {
	    double fieldOfView;

	    if (viewerList.size() == 0) {
		// No Viewer associated with this ViewingPlatform, so use the
		// default field of view value to move the ViewingPlatform.
		fieldOfView = Math.PI/4.0;
	    }
	    else {
		if (viewerList.size() > 1) {
		    throw new RuntimeException
			(J3dUtilsI18N.getString("ViewingPlatform0"));
		}

		Viewer viewer = (Viewer)viewerList.keys().nextElement();
		View view = viewer.getView();
		fieldOfView = view.getFieldOfView();
	    }

	    Transform3D t3d = new Transform3D();
	    double viewDistance = 1.0/Math.tan(fieldOfView/2.0);
	    t3d.set(new Vector3d(0.0, 0.0, viewDistance));
	    getViewPlatformTransform().setTransform(t3d);
	}
    }

    /**
     * Returns the avatarRoot child number of the ViewerAvatar object.
     * All the children of the avatarRoot are compared with the passed
     * in ViewerAvatar.  If a match is found, the index is returned.
     *
     * @param avatar The ViewerAvatar object to look for in the avatarRoot's
     *  child nodes.
     * @return The index of the child that corresponds to the ViewerAvatar.
     *  If the avatarRoot does not contain the ViewerAvatar -1 is returned.
     */
    private int findAvatarChild(ViewerAvatar avatar) {
        // Search the avatarRoot for the ViewerAvatar associated with
        // with the Viewer object
        for (int i = 0; i < avatarRoot.numChildren(); i++) {
            if (((ViewerAvatar)avatarRoot.getChild(i)) == avatar)
                return i;
        }

        // Should never get here.
        System.err.println("ViewingPlatform.findAvatarChild:Child not found.");
        return -1;
    }

    /**
     * Adds the ViewerAvatar to the scene graph.  An avatar (geometry)
     * can be associated with a Viewer object and displayed by Java 3D.
     *
     * @param viewer The viewer object to associate with this avatar.
     * @param avatar The avatar to add to the scene graph.  Passing in
     *  null removes any currently assigned avatar.
     */
    void setAvatar(Viewer viewer, ViewerAvatar avatar) {
        Object oldAvatar = viewerList.get(viewer);

        // A position of -1 means the avatar is not a child of the avatarRoot.
        int avatarPosition = -1;

        // Because "null" cannot be used in a put the avatarRoot object
        // is used to signify that there is no ViewerAvatar associated
        // with this Viewer.
        if (oldAvatar != avatarRoot)
            avatarPosition = findAvatarChild((ViewerAvatar)oldAvatar);

        // If the avatar is null, will be removing any geometry already present.
        if (avatar == null) {
            if (avatarPosition != -1) {
                avatarRoot.removeChild(avatarPosition);

                // Reset hashtable entry - avatarRoot == null.
                viewerList.put(viewer, avatarRoot);
            }
        }
        else {
            // see if there is an old ViewerAvater to replace
            if (avatarPosition != -1)
                avatarRoot.setChild(avatar, avatarPosition);
            else
                avatarRoot.addChild(avatar);

            // Update hashtable with new avatar.
            viewerList.put(viewer, avatar);
        }
    }

    /**
     * When a ViewingPlatform is set by a Viewer, the ViewingPlatform
     * needs to be informed, via a call to this method.  This will add
     * the Viewer to the ViewingPlatform's viewerList for use when
     * things such as the PlatformGeometry are changed and all Viewer
     * scene graphs need to be modified.
     */
    void addViewer(Viewer viewer) {
        // Because the viewerList is also used to associate ViewerAvatars
        // with Viewer objects a hashtable is used. This routine does not
        // check for the presence of a ViewerAvatar but the Viewer still
        // needs to be added to the hashtable.  Because "null" cannot be
        // used in a put the avatarRoot object is used to signify that there
        // is no ViewerAvatar associated with this Viewer.
        viewerList.put(viewer, avatarRoot);
    }

    /*
     * Cleanup when Viewer set another ViewingPlatform
     */
    void removeViewer(Viewer viewer) {
	viewerList.remove(viewer);
    }
    
    /**
     * Adds a new ViewPlatformBehavior to the ViewingPlatform
     */
    void addViewPlatformBehavior(ViewPlatformBehavior behavior) {
	behavior.setViewingPlatform(this);
 	if (behaviors == null) {
 	    behaviors = new BranchGroup();
 	    behaviors.setCapability(BranchGroup.ALLOW_DETACH);
	    behaviors.setCapability(BranchGroup.ALLOW_CHILDREN_READ);
 	}
 	// otherwise detach the BranchGroup so we can add to it
	else {
	    behaviors.detach();
	}
	behaviors.addChild(behavior);
	this.addChild(behaviors);
    }

    /**
     * Sets the ViewPlatformBehavior which will operate on the ViewPlatform
     * transform (the TransformGroup returned by
     * ViewingPlatform.getViewPlatformTransform()). The ViewPlatformBehavior
     * may be set after the ViewingPlatform is setLive().
     * If a behavior is already present, it will be detached and it's
     * setViewingPlatform method will be called with a parameter of null.
     * @param behavior The ViewPlatformBehavior to add to the ViewingPlatform.
     * null will remove the ViewingPlatform behavior.
     * @since Java 3D 1.2.1
     */
    public void setViewPlatformBehavior(ViewPlatformBehavior behavior) {
	if (behaviors != null) {
	    removeViewPlatformBehavior((ViewPlatformBehavior)behaviors.getChild(0));
	}
	if (behavior != null) {
	    addViewPlatformBehavior(behavior);
	}
    }

    /**
     * Removes the specified ViewPlatformBehavior
     */
    void removeViewPlatformBehavior(ViewPlatformBehavior behavior) {
	// remove from the behaviors branch group
	if (behaviors != null) {
	    behaviors.detach();
	    for (int i = 0; i < behaviors.numChildren(); i++) {
		if (behaviors.getChild(i) == behavior) {
	            behavior.setViewingPlatform( null );
		    behaviors.removeChild(i);
		    break;
		}
	    }
	    if (behaviors.numChildren() == 0) behaviors = null;
	    else this.addChild(behaviors);
	}
    }
    
    /**
     * Returns the number of ViewPlatformBehaviors on the ViewingPlatform
     */
    int getViewPlatformBehaviorCount() {
	return behaviors.numChildren();
    }
    
    /**
     * Returns the ViewPlatformBehavior at the specified index
     */
    ViewPlatformBehavior getViewPlatformBehavior(int index) {
	return (ViewPlatformBehavior)behaviors.getChild(index);
    }

    /**
     * Returns the ViewPlatformBehavior
     * @return the ViewPlatformBehavior for the ViewingPlatform.
     * Returns null if there is no ViewPlatformBehavior set.
     * @since Java 3D 1.2.1
     */
    public ViewPlatformBehavior getViewPlatformBehavior() {
	if (behaviors == null) {
	    return null;
	}
	return getViewPlatformBehavior(0);
    }
    
    /**
     * Returns the Viewers attached to this ViewingPlatform
     *
     * @return the Viewers attached to this viewing platform
     * @since Java 3D 1.3
     */
    public Viewer[] getViewers() {
	if (viewerList.size() == 0) return null;
        return (Viewer[])viewerList.keySet().toArray( new Viewer[0] );
    }
    
    /**
     * Returns the Universe to which this ViewingPlatform is attached
     *
     * @return the Universe to which this ViewingPlatform is attached
     * @since Java 3D 1.3
     */
    public SimpleUniverse getUniverse() {
        return universe;
    }
    
    /**
     * Sets the Universe to which this ViewingPlatform is attached
     *
     * @param universe the Universe to which this ViewingPlatform is attached
     * @since Java 3D 1.3
     */
    public void setUniverse( SimpleUniverse universe ) {
        this.universe = universe;
    }
}