* * The landscape is used to control what it rendered on screen as the user * moves about the virtual environment. This instance does not need to maintain * all the polygons on the screen at any one time, but may control them as * needed. *
* * This object is independent of the culling algorithm. It represents something * that can be placed in a scenegraph and have view information passed to it * without the need to know the specific algorithm in use. To implement a * specific algorithm (eg ROAM) you would extend this class and implement the * {@link #setView(Tuple3f, Vector3f)} method. Every time that the scene * changes, you will be notified by this method. That means you should perform * any culling/LOD and update the scene graph at this point. This will be * called at most once per frame. *
*
* For convenience, this class also implements {@link FrameUpdateListener} from
* the {@link org.j3d.ui.navigation} package so that you can have fast, quick
* navigation implementation in your code. If you wish to use your own custom
* user input code, then there is no penalty for doing so. Simply call one of
* the setView() methods directly with the transformation
* information.
*
* * If you are going to use this class with the navigation code, then you * should also make the internal geometry not pickable, and make this item * pickable. In this way, the navigation code will find this top-level * terrain definition and use it directly to make the code much faster. None * of these capabilities are set within this implementation, so it is up to * the third-party code to make it so via calls to the appropriate methods. *
* * The landscape provides an appearance generator for letting the end user * application control appearance settings. If this is not set then particular * implementation is free to do what it likes. * * @author Justin Couch, based on original ideas from Paul Byrne * @version $Revision: 1.1 $ */ public abstract class J3DAbstractLandscape extends Landscape implements FrameUpdateListener, J3DLandscape { /** Generator for appearance information. May be null */ protected AppearanceGenerator appearanceGenerator; /** * Temporary variable to hold the position information extracted from * the full transform class. */ private Vector3f tmpPosition; /** * Temporary variable to hold the orientation information extracted from * the matrix class. */ private Vector3f tmpOrientation; /** * Temporary variable to hold the orientation matrix extracted from * the full transform class. */ private Matrix3f tmpMatrix; /** Geometry used to represent this terrain at the J3D level */ protected BranchGroup rootGroup; /** * Create a new Landscape with the set view and data. If either are not * provided, an exception is thrown. Uses the default appearance generator. * * @param view The viewing frustum to see the data with * @param data The raw data to view * @throws IllegalArgumentException either parameter is null */ public J3DAbstractLandscape(ViewFrustum view, TerrainData data) { super(view, data); tmpPosition = new Vector3f(); tmpOrientation = new Vector3f(); tmpMatrix = new Matrix3f(); rootGroup = new BranchGroup(); } /** * Provide a landscape with a specific appearance generator set. If the * generator argument is null, then the default is used. * * @param view The viewing frustum to see the data with * @param data The raw data to view * @param gen The generator instance to use * @throws IllegalArgumentException either parameter is null */ public J3DAbstractLandscape(ViewFrustum view, TerrainData data, AppearanceGenerator gen) { this(view, data); appearanceGenerator = gen; } //---------------------------------------------------------- // Methods required by FrameUpdateListener //---------------------------------------------------------- /** * The transition from one point to another is completed. Use this to * update the transformation. * * @param t3d The position of the final viewpoint */ public void transitionEnded(Transform3D t3d) { landscapeView.viewingPlatformMoved(); setView(t3d); } /** * The frame has just been updated with the latest view information. * Update the landscape rendered values now. * * @param t3d The position of the viewpoint now */ public void viewerPositionUpdated(Transform3D t3d) { landscapeView.viewingPlatformMoved(); setView(t3d); } //---------------------------------------------------------- // Local methods //---------------------------------------------------------- /** * Set the current view location information based on a transform matrix. * Only the position and orientation information are extracted from this * matrix. Any shear or scale is ignored. Effectively, this transform * should be the view transform (particularly if you are using navigation * code from this codebase in the {@link org.j3d.ui.navigation} package. * * @param t3d The transform to use as the view position */ public void setView(Transform3D t3d) { t3d.get(tmpMatrix, tmpPosition); tmpOrientation.set(0, 0, -1); tmpMatrix.transform(tmpOrientation); setView(tmpPosition, tmpOrientation); } /** * Set the appearance generator to create new appearanace items. If null * is passed, it clears the current appearance settings * * @param gen The new generator instance to use */ public void setAppearanceGenerator(AppearanceGenerator gen) { appearanceGenerator = gen; } /** * Get the currently set appearance generator. If not set, returns null. * * @return The current generator instance */ public AppearanceGenerator getAppearanceGenerator() { return appearanceGenerator; } /** * Get the geometry group that this terrain is being rendered to. * * @return The parent group for all the terrain */ public BranchGroup getSceneGraphObject() { return rootGroup; } }