org.j3d.terrain

Class Landscape

java.lang.Object

org.j3d.terrain.Landscape

All Implemented Interfaces:

HeightDataSource, HeightMapGeometry

Direct Known Subclasses:

ROAMSplitMergeLandscape

public abstract class Landscape
extends Object
implements HeightMapGeometry

Representation of a piece of rendered terrain data.

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 setView(Point3d, Vector3d) 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.

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.

Internationalisation Resource Names

• nullViewFrustumMsg: The view frustum in the constructor is null
• nullTerrainDataMsg: The terrain data in the constructor is null

Version:

$Revision: 1.11 $

Author:

Justin Couch, based on original ideas from Paul Byrne

Field Summary

Fields

Modifier and Type	Field and Description
protected org.j3d.util.frustum.ViewFrustum	landscapeView The current viewing frustum that is seeing the landscape
protected TerrainData	terrainData Raw terrain information to be rendered

Constructor Summary

Constructors

Constructor and Description
Landscape(org.j3d.util.frustum.ViewFrustum view, TerrainData data) Create a new Landscape with the set view and data.

Method Summary

Modifier and Type	Method and Description
float	getHeight(float x, float z) Get the height at the given X,Z coordinate in the local coordinate system.
abstract void	initialize(org.j3d.maths.vector.Point3d position, org.j3d.maths.vector.Vector3d direction) Initialise the landscape ready for viewing.
abstract void	setView(org.j3d.maths.vector.Point3d position, org.j3d.maths.vector.Vector3d direction) Set the current viewing direction for the user.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

landscapeView

protected org.j3d.util.frustum.ViewFrustum landscapeView

The current viewing frustum that is seeing the landscape

terrainData

protected TerrainData terrainData

Raw terrain information to be rendered

Constructor Detail

Landscape

public Landscape(org.j3d.util.frustum.ViewFrustum view,
                 TerrainData data)

Create a new Landscape with the set view and data. If either are not provided, an exception is thrown. Uses the default appearance generator.

Parameters:

view - The viewing frustum to see the data with

data - The raw data to view

Throws:

IllegalArgumentException - either parameter is null

Method Detail

getHeight

public float getHeight(float x,
                       float z)

Get the height at the given X,Z coordinate in the local coordinate system. This implementation delegates to the underlying terrain data to do the real resolution.

Specified by:

getHeight in interface HeightDataSource

Parameters:

x - The x coordinate for the height sampling

z - The z coordinate for the height sampling

Returns:

The height at the current point or NaN

initialize

public abstract void initialize(org.j3d.maths.vector.Point3d position,
                                org.j3d.maths.vector.Vector3d direction)

Initialise the landscape ready for viewing. This should be called before you add the parent branchgroup to the live scenegraph as the implementation code will need to construct the renderable scene graph. It also sets the initial position so that if the terrain is using tilable datasets it can determine where to start building from.

Parameters:

position - The position the user is in the virtual world

direction - The orientation of the user's gaze

setView

public abstract void setView(org.j3d.maths.vector.Point3d position,
                             org.j3d.maths.vector.Vector3d direction)

Set the current viewing direction for the user. The user is located at the given point and looking in the given direction. All information is assumed to be in world coordinates.

Parameters:

position - The position the user is in the virtual world

direction - The orientation of the user's gaze