Package com.jme3.terrain.geomipmap

Class TerrainPatch

java.lang.Object
com.jme3.scene.Spatial
com.jme3.scene.Geometry
com.jme3.terrain.geomipmap.TerrainPatch
All Implemented Interfaces:
HasLocalTransform, CloneableSmartAsset, Collidable, Savable, JmeCloneable, Cloneable
public class TerrainPatch extends Geometry
A terrain patch is a leaf in the terrain quad tree. It has a mesh that can change levels of detail (LOD) whenever the view point, or camera, changes. The actual terrain mesh is created by the LODGeomap class. That uses a geo-mipmapping algorithm to change the index buffer of the mesh. The mesh is a triangle strip. In wireframe mode you might notice some strange lines, these are degenerate triangles generated by the geoMipMap algorithm and can be ignored. The video card removes them at almost no cost. Each patch needs to know its neighbour's LOD so it can seam its edges with them, in case the neighbour has a different LOD. If this doesn't happen, you will see gaps. The LOD value is most detailed at zero. It gets less detailed the higher the LOD value until you reach maxLod, which is a mathematical limit on the number of times the 'size' of the patch can be divided by two. However, there is a -1 to that for now until I add in a custom index buffer calculation for that max level, the current algorithm does not go that far. You can supply a LodThresholdCalculator for use in determining when the LOD should change. Its API will no doubt change in the near future. Right now it defaults to just changing LOD every two patch sizes. So if a patch has a size of 65, then the LOD changes every 130 units away.

  • Field Details

    • geomap

      protected LODGeomap geomap

    • lod

      protected int lod

    • previousLod

      protected int previousLod

    • lodLeft

      protected int lodLeft

    • lodTop

      protected int lodTop

    • lodRight

      protected int lodRight

    • lodBottom

      protected int lodBottom

    • size

      protected int size

    • totalSize

      protected int totalSize

    • quadrant

      protected short quadrant

    • stepScale

      protected Vector3f stepScale

    • offset

      protected Vector2f offset

    • offsetAmount

      protected float offsetAmount

    • leftNeighbour

      protected TerrainPatch leftNeighbour

    • topNeighbour

      protected TerrainPatch topNeighbour

    • rightNeighbour

      protected TerrainPatch rightNeighbour

    • bottomNeighbour

      protected TerrainPatch bottomNeighbour

    • searchedForNeighboursAlready

      protected boolean searchedForNeighboursAlready

    • worldTranslationCached

      protected Vector3f worldTranslationCached

    • worldScaleCached

      protected Vector3f worldScaleCached

    • lodEntropy

      protected float[] lodEntropy

  • Constructor Details

    • TerrainPatch

      public TerrainPatch()

    • TerrainPatch

      public TerrainPatch(String name)

    • TerrainPatch

      public TerrainPatch(String name, int size)

    • TerrainPatch

      public TerrainPatch(String name, int size, Vector3f stepScale, float[] heightMap, Vector3f origin)
      Constructor instantiates a new TerrainPatch object. The parameters and heightmap data are then processed to generate a TriMesh object for rendering.
      Parameters:
      name - the name of the terrain patch.
      size - the size of the heightmap.
      stepScale - the scale for the axes.
      heightMap - the height data.
      origin - the origin offset of the patch.

    • TerrainPatch

      public TerrainPatch(String name, int size, Vector3f stepScale, float[] heightMap, Vector3f origin, int totalSize, Vector2f offset, float offsetAmount)
      Constructor instantiates a new TerrainPatch object. The parameters and heightmap data are then processed to generate a TriMesh object for rendering.
      Parameters:
      name - the name of the terrain patch.
      size - the size of the patch.
      stepScale - the scale for the axes.
      heightMap - the height data.
      origin - the origin offset of the patch.
      totalSize - the total size of the terrain. (Higher if the patch is part of a TerrainQuad tree.)
      offset - the offset for texture coordinates.
      offsetAmount - the total offset amount. Used for texture coordinates.

  • Method Details

    • generateLodEntropies

      public void generateLodEntropies()
      This calculation is slow, so don't use it often.

    • getLodEntropies

      public float[] getLodEntropies()

    • getHeightMap

      public float[] getHeightMap()

    • getMaxLod

      public int getMaxLod()
      The maximum lod supported by this terrain patch. If the patch size is 32 then the returned value would be log2(32)-2 = 3 You can then use that value, 3, to see how many times you can divide 32 by 2 before the terrain gets too un-detailed (can't stitch it any further).
      Returns:
      the maximum LOD

    • reIndexGeometry

      protected void reIndexGeometry(HashMap<String,UpdatedTerrainPatch> updated, boolean useVariableLod)

    • getTex

      public Vector2f getTex(float x, float z, Vector2f store)

    • getHeightmapHeight

      public float getHeightmapHeight(float x, float z)

    • getTriangle

      public Triangle getTriangle(float x, float z)
      Get the triangle of this geometry at the specified local coordinate.
      Parameters:
      x - local to the terrain patch
      z - local to the terrain patch
      Returns:
      the triangle in world coordinates, or null if the point does intersect this patch on the XZ axis

    • getGridTriangles

      public Triangle[] getGridTriangles(float x, float z)
      Get the triangles at the specified grid point. Probably only 2 triangles
      Parameters:
      x - local to the terrain patch
      z - local to the terrain patch
      Returns:
      the triangles in world coordinates, or null if the point does intersect this patch on the XZ axis

    • setHeight

      protected void setHeight(List<TerrainQuad.LocationHeight> locationHeights, boolean overrideHeight)

    • updateNormals

      protected void updateNormals()
      Recalculates all normal vectors in this terrain patch.

    • fixNormalEdges

      protected void fixNormalEdges(TerrainPatch right, TerrainPatch bottom, TerrainPatch top, TerrainPatch left, TerrainPatch bottomRight, TerrainPatch bottomLeft, TerrainPatch topRight, TerrainPatch topLeft)
      Matches the normals along the edge of the patch with the neighbours. Computes the normals for the right, bottom, left, and top edges of the patch, and saves those normals in the neighbour's edges too. Takes 4 points (if it has a neighbour on that side) for each point on the edge of the patch: * | *---x---* | * It works across the right side of the patch, from the top down to the bottom. Then it works on the bottom side of the patch, from the left to the right.

    • averageNormalsTangents

      protected void averageNormalsTangents(Vector3f topPoint, Vector3f rootPoint, Vector3f leftPoint, Vector3f bottomPoint, Vector3f rightPoint, Vector3f normal, Vector3f tangent, Vector3f binormal)

    • getMeshNormal

      protected Vector3f getMeshNormal(int x, int z)

    • getHeight

      protected float getHeight(int x, int z, float xm, float zm)

    • lockMesh

      public void lockMesh()
      Locks the mesh (sets it static) to improve performance. If it is not editable, then unlock to make it editable.

    • unlockMesh

      public void unlockMesh()
      Unlocks the mesh (sets it dynamic) to make it editable. It will be editable but performance will be reduced. Call lockMesh to improve performance.

    • getOffsetAmount

      public float getOffsetAmount()
      Returns the offset amount this terrain patch uses for textures.
      Returns:
      The current offset amount.

    • getStepScale

      public Vector3f getStepScale()
      Returns the step scale that stretches the height map.
      Returns:
      The current step scale.

    • getTotalSize

      public int getTotalSize()
      Returns the total size of the terrain.
      Returns:
      The terrain's total size.

    • getSize

      public int getSize()
      Returns the size of this terrain patch.
      Returns:
      The current patch size.

    • getOffset

      public Vector2f getOffset()
      Returns the current offset amount. This is used when building texture coordinates.
      Returns:
      The current offset amount.

    • setOffset

      public void setOffset(Vector2f offset)
      Sets the value for the current offset amount to use when building texture coordinates. Note that this does NOT rebuild the terrain at all. This is mostly used for outside constructors of terrain patches.
      Parameters:
      offset - The new texture offset.

    • setSize

      public void setSize(int size)
      Sets the size of this terrain patch. Note that this does NOT rebuild the terrain at all. This is mostly used for outside constructors of terrain patches.
      Parameters:
      size - The new size.

    • setTotalSize

      public void setTotalSize(int totalSize)
      Sets the total size of the terrain . Note that this does NOT rebuild the terrain at all. This is mostly used for outside constructors of terrain patches.
      Parameters:
      totalSize - The new total size.

    • setStepScale

      public void setStepScale(Vector3f stepScale)
      Sets the step scale of this terrain patch's height map. Note that this does NOT rebuild the terrain at all. This is mostly used for outside constructors of terrain patches.
      Parameters:
      stepScale - The new step scale.

    • setOffsetAmount

      public void setOffsetAmount(float offsetAmount)
      Sets the offset of this terrain texture map. Note that this does NOT rebuild the terrain at all. This is mostly used for outside constructors of terrain patches.
      Parameters:
      offsetAmount - The new texture offset.

    • getQuadrant

      public short getQuadrant()
      Returns:
      Returns the quadrant.

    • setQuadrant

      public void setQuadrant(short quadrant)
      Parameters:
      quadrant - The quadrant to set.

    • getLod

      public int getLod()

    • setLod

      public void setLod(int lod)

    • getPreviousLod

      public int getPreviousLod()

    • setPreviousLod

      public void setPreviousLod(int previousLod)

    • getLodLeft

      protected int getLodLeft()

    • setLodLeft

      protected void setLodLeft(int lodLeft)

    • getLodTop

      protected int getLodTop()

    • setLodTop

      protected void setLodTop(int lodTop)

    • getLodRight

      protected int getLodRight()

    • setLodRight

      protected void setLodRight(int lodRight)

    • getLodBottom

      protected int getLodBottom()

    • setLodBottom

      protected void setLodBottom(int lodBottom)

    • collideWith

      public int collideWith(Collidable other, CollisionResults results) throws UnsupportedCollisionException
      Description copied from interface: Collidable
      Check collision with another Collidable.
      Specified by:
      collideWith in interface Collidable
      Overrides:
      collideWith in class Geometry
      Parameters:
      other - The object to check collision against
      results - Will contain the list of CollisionResults.
      Returns:
      how many collisions were found between this and other
      Throws:
      UnsupportedCollisionException

    • worldCoordinateToLocal

      protected Vector3f worldCoordinateToLocal(Vector3f loc)

    • write

      public void write(JmeExporter ex) throws IOException
      Specified by:
      write in interface Savable
      Overrides:
      write in class Geometry
      Throws:
      IOException

    • read

      public void read(JmeImporter im) throws IOException
      Specified by:
      read in interface Savable
      Overrides:
      read in class Geometry
      Throws:
      IOException

    • clone

      public TerrainPatch clone()
      Description copied from class: Geometry
      This version of clone is a shallow clone, in other words, the same mesh is referenced as the original geometry. Exception: if the mesh is marked as being a software animated mesh, (bind pose is set) then the positions and normals are deep copied.
      Specified by:
      clone in interface CloneableSmartAsset
      Overrides:
      clone in class Geometry
      Returns:
      A clone of this Spatial, the scene graph in its entirety is cloned and can be altered independently of the original scene graph. Note that meshes of geometries are not cloned explicitly, they are shared if static, or specially cloned if animated.
      See Also:

    • cloneFields

      public void cloneFields(Cloner cloner, Object original)
      Called internally by com.jme3.util.clone.Cloner. Do not call directly.
      Specified by:
      cloneFields in interface JmeCloneable
      Overrides:
      cloneFields in class Geometry
      Parameters:
      cloner - The cloner that is performing the cloning operation. The cloneFields method can call back into the cloner to make clones of its subordinate fields.
      original - The original object from which this object was cloned. This is provided for the very rare case that this object needs to refer to its original for some reason. In general, all of the relevant values should have been transferred during the shallow clone, and this object need only clone what it wants.

    • ensurePositiveVolumeBBox

      protected void ensurePositiveVolumeBBox()

    • cacheTerrainTransforms

      protected void cacheTerrainTransforms()
      Caches the transforms (except rotation) so the LOD calculator, which runs on a separate thread, can access them safely.

    • getWorldScaleCached

      public Vector3f getWorldScaleCached()

    • getWorldTranslationCached

      public Vector3f getWorldTranslationCached()

    • clearCaches

      protected void clearCaches()
      Removes any references when the terrain is being removed.