Package com.jme3.terrain.heightmap

Class MidpointDisplacementHeightMap

java.lang.Object

com.jme3.terrain.heightmap.AbstractHeightMap

com.jme3.terrain.heightmap.MidpointDisplacementHeightMap

All Implemented Interfaces:

HeightMap

public class MidpointDisplacementHeightMap
extends AbstractHeightMap

MidpointDisplacementHeightMap generates a heightmap based on the midpoint displacement algorithm. See Constructor javadoc for more info.

Field Summary

Fields inherited from class com.jme3.terrain.heightmap.AbstractHeightMap

filter, heightData, heightScale, NORMALIZE_RANGE, size

Constructor Summary

Constructors

Constructor	Description
MidpointDisplacementHeightMap(int size, float range, float persistence)	The constructor generates the heightmap.
MidpointDisplacementHeightMap(int size, float range, float persistence, long seed)	The constructor generates the heightmap.

Method Summary

Modifier and Type	Method	Description
protected int[]	doDiamondStep(float[][] tempBuffer, int[] coords, int stepSize, float offsetRange, Random random)	Will fill the cell at (x+stepSize/2, y) with the average of the 4 corners of the diamond centered on that point with width and height of stepSize.
protected int[]	doSquareStep(float[][] tempBuffer, int[] coords, int stepSize, float offsetRange, Random random)	Will fill the value at (coords[0]+stepSize/2, coords[1]+stepSize/2) with the average from the corners of the square with top, left corner at (coords[0],coords[1]) and width of stepSize.
protected float	getOffset(Random random, float offsetRange, int[] coords, float average)	Generate a random value to add to the computed average
float	getPersistence()
float	getRange()
long	getSeed()
boolean	load()	Generate the heightmap.
void	setPersistence(float persistence)
void	setRange(float range)
void	setSeed(long seed)

Methods inherited from class com.jme3.terrain.heightmap.AbstractHeightMap

erodeTerrain, findMinMaxHeights, flatten, getHeightMap, getInterpolatedHeight, getScaledHeightAtPoint, getScaledHeightMap, getSize, getTrueHeightAtPoint, normalizeTerrain, save, setHeightAtPoint, setHeightScale, setMagnificationFilter, setSize, smooth, smooth, unloadHeightMap

Methods inherited from class java.lang.Object

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

Constructor Details

MidpointDisplacementHeightMap

public MidpointDisplacementHeightMap(int size,
 float range,
 float persistence,
 long seed)

The constructor generates the heightmap. After the first 4 corners are randomly given a height, the center height will be set to the average of the 4 corners plus a random value. Then other passes fill the heightmap by the same principle. The random value is generated between the values -range and range. The range parameter is multiplied by the persistence parameter each pass to smoothen close cell heights. Extends this class and override the getOffset function for more control of the randomness (you can use the coordinates and/or the computed average height to influence the random amount added.

Parameters:

size - The size of the heightmap, must be 2^N+1

range - The range in which randomness will be added. A value of 1 will allow -1 to 1 value changes.

persistence - The factor by which the range will evolve at each iteration. A value of 0.5f will halve the range at each iteration and is typically a good choice

seed - A seed to feed the random number generator.

Throws:

IllegalArgumentException - if size is not a power of two plus one.

MidpointDisplacementHeightMap

public MidpointDisplacementHeightMap(int size,
 float range,
 float persistence)
                              throws Exception

The constructor generates the heightmap. After the first 4 corners are randomly given a height, the center height will be set to the average of the 4 corners plus a random value. Then other passes fill the heightmap by the same principle. The random value is generated between the values -range and range. The range parameter is multiplied by the persistence parameter each pass to smoothen close cell heights.

Parameters:

size - The size of the heightmap, must be 2^N+1

range - The range in which randomness will be added. A value of 1 will allow -1 to 1 value changes.

persistence - The factor by which the range will evolve at each iteration. A value of 0.5f will halve the range at each iteration and is typically a good choice

Throws:

IllegalArgumentException - if size is not a power of two plus one.

Exception

Method Details

load

public boolean load()

Generate the heightmap.

Returns:

true

doSquareStep

protected int[] doSquareStep(float[][] tempBuffer,
 int[] coords,
 int stepSize,
 float offsetRange,
 Random random)

Will fill the value at (coords[0]+stepSize/2, coords[1]+stepSize/2) with the average from the corners of the square with top, left corner at (coords[0],coords[1]) and width of stepSize.

Parameters:

tempBuffer - the temporary heightmap

coords - an int array of length 2 with the x coord in position 0

stepSize - the size of the square

offsetRange - the offset range within a random value is picked and added to the average

random - the random generator

Returns:

a new array or null

doDiamondStep

protected int[] doDiamondStep(float[][] tempBuffer,
 int[] coords,
 int stepSize,
 float offsetRange,
 Random random)

Will fill the cell at (x+stepSize/2, y) with the average of the 4 corners of the diamond centered on that point with width and height of stepSize.

Parameters:

tempBuffer -

coords -

stepSize -

offsetRange -

random -

Returns:

a new array or null

getOffset

protected float getOffset(Random random,
 float offsetRange,
 int[] coords,
 float average)

Generate a random value to add to the computed average

Parameters:

random - the random generator

offsetRange -

coords -

average -

Returns:

A semi-random value within offsetRange

getPersistence

public float getPersistence()

setPersistence

public void setPersistence(float persistence)

getRange

public float getRange()

setRange

public void setRange(float range)

getSeed

public long getSeed()

setSeed

public void setSeed(long seed)