gf::Heightmap Class Reference

A heightmap. More...

#include <gf/Heightmap.h>

Public Types
enum class	Render {   Colored ,   Shaded }
	Rendering mode. More...

Public Member Functions
	Heightmap ()=default
	Default constructor. More...
	Heightmap (Vector2i size)
	Constructor. More...
Vector2i	getSize () const
	Get the size of the heightmap. More...
void	reset ()
	Reset the heightmap. More...
double	getValue (Vector2i position) const
	Get the value at the specified position. More...
void	setValue (Vector2i position, double value)
	Set the value at the specified position. More...
std::tuple< double, double >	getMinMax () const
	Get the minimum and maximum of the heightmap. More...
Shaping
void	normalize (double min=0.0, double max=1.0)
	Normalize the heightmap. More...
void	addHill (Vector2d center, double radius, double height)
	Add a hill to the heightmap. More...
void	digHill (Vector2d center, double radius, double height)
	Dig a hill in the heightmap. More...
void	addNoise (Noise2D &noise, double scale=1.0)
	Add a noise to the heightmap. More...
void	addValue (double value)
	Add a constant to the heightmap. More...
void	scale (double value)
	Scale the values of the heightmap. More...
void	clamp (double min=0.0, double max=1.0)
	Clamp the values of the heightmap. More...
Erosion
double	getSlope (Vector2i position) const
	Compute the slope at a position. More...
void	thermalErosion (unsigned iterations, double talus, double fraction)
	Apply thermal erosion to the heightmap. More...
void	hydraulicErosion (unsigned iterations, double rainAmount, double solubility, double evaporation, double capacity)
	Apply hydraulic erosision to the heightmap. More...
void	fastErosion (unsigned iterations, double talus, double fraction)
	Apply fast erosion to the heightmap. More...
double	getErosionScore () const
	Compute the erosion score for the heightmap. More...
Export
Heightmap	subMap (RectI area) const
	Get a sub-map of the heightmap. More...
Image	copyToGrayscaleImage () const
	Export to a grayscale image. More...
Image	copyToColoredImage (const ColorRampD &ramp, double waterLevel=0.5, Render render=Render::Colored) const
	Export to a colored image. More...

Detailed Description

A heightmap.

See also

gf::midpointDisplacement2D(), gf::diamondSquare2D()

Member Enumeration Documentation

Render

enum class gf::Heightmap::Render

strong

Rendering mode.

Enumerator
Colored	Export to a simply colored image.
Shaded	Export to a shaded image.

Constructor & Destructor Documentation

Heightmap() [1/2]

gf::Heightmap::Heightmap ( )

default

Default constructor.

Heightmap() [2/2]

gf::Heightmap::Heightmap

(

Vector2i

size

)

Constructor.

Parameters

size	The size of the heightmap

Member Function Documentation

addHill()

void gf::Heightmap::addHill	(	Vector2d	center,
		double	radius,
		double	height
	)

Add a hill to the heightmap.

Parameters

center	The center of the hill
radius	The radius of the hill
height	The height of the hill

addNoise()

void gf::Heightmap::addNoise	(	Noise2D &	noise,
		double	scale = 1.0
	)

Add a noise to the heightmap.

Parameters

noise	The noise to use
scale	The scale of the noise

addValue()

void gf::Heightmap::addValue

(

double

value

)

Add a constant to the heightmap.

Parameters

value

The value of the constant

clamp()

void gf::Heightmap::clamp	(	double	min = 0.0,
		double	max = 1.0
	)

Clamp the values of the heightmap.

Parameters

min	The minimum value (defaults to \( 0.0 \))
max	The maximum value (defaults to \( 1.0 \))

See also

normalize()

copyToColoredImage()

Image gf::Heightmap::copyToColoredImage	(	const ColorRampD &	ramp,
		double	waterLevel = 0.5,
		Render	render = Render::Colored
	)		const

Export to a colored image.

The heightmap is assumed to be normalized.

The color ramp assumes that the water level is at \( 0.5 \). The actual water level can be specified and the ramp is automatically adapted on the fly.

Parameters

ramp	A color ramp
waterLevel	The actual water level (defaults to \( 0.5 \))
render	The rendering mode

Returns

A colored image representing the heightmap

See also

copyToGrayscaleImage()

copyToGrayscaleImage()

Image gf::Heightmap::copyToGrayscaleImage

(

)

const

Export to a grayscale image.

The heightmap is assumed to be normalized.

Returns

A grayscale image representing the heightmap

See also

copyToColoredImage()

digHill()

void gf::Heightmap::digHill	(	Vector2d	center,
		double	radius,
		double	height
	)

Dig a hill in the heightmap.

Parameters

center	The center of the hill
radius	The radius of the hill
height	The height of the hill

fastErosion()

void gf::Heightmap::fastErosion	(	unsigned	iterations,
		double	talus,
		double	fraction
	)

Apply fast erosion to the heightmap.

Parameters

iterations	The number of iterations
talus	The maximum difference for a move of material (typically \( \frac{8}{N} \) or more)
fraction	The fraction of material that moves (typically \( 0.5 \))

getErosionScore()

double gf::Heightmap::getErosionScore

(

)

const

Compute the erosion score for the heightmap.

The erosion score is the average slope divided by the standard deviation of slopes. A high erosion score means that the terrain has large flat areas and has some steep areas.

getMinMax()

std::tuple< double, double > gf::Heightmap::getMinMax

(

)

const

Get the minimum and maximum of the heightmap.

Returns

A pair with the first element being the minimum and the second element the maximum

getSize()

Vector2i gf::Heightmap::getSize ( ) const

inline

Get the size of the heightmap.

Returns

The current size of the heightmap

getSlope()

double gf::Heightmap::getSlope

(

Vector2i

position

)

const

Compute the slope at a position.

The slope is defined as "the greatest of the height differences between the cell and its four neighbours in a Von Neumann neighbourhood".

\[ \text{slope}(x, y) = \max(|h(x,y) - h(x - 1, y)|, |h(x,y) - h(x + 1, y)|, |h(x,y) - h(x, y - 1)|, |h(x,y) - h(x, y + 1)|) \]

Parameters

position

The given position

getValue()

double gf::Heightmap::getValue ( Vector2i  position ) const

inline

Get the value at the specified position.

Parameters

position

A position

Returns

The value at the given position

hydraulicErosion()

void gf::Heightmap::hydraulicErosion	(	unsigned	iterations,
		double	rainAmount,
		double	solubility,
		double	evaporation,
		double	capacity
	)

Apply hydraulic erosision to the heightmap.

Parameters

iterations	The number of iterations
rainAmount	The amount of rain each cell receives at each iteration (typically \( 0.01 \))
solubility	The solubility of the terrain (typically \( 0.01 \))
evaporation	The proportion of evaporated water at each iteration (typically \( 0.5 \))
capacity	The maximum proportion of material that can be carried by water (typically \( 0.01 \))

normalize()

void gf::Heightmap::normalize	(	double	min = 0.0,
		double	max = 1.0
	)

Normalize the heightmap.

Parameters

min	The new minimum value (defaults to \( 0.0 \))
max	The new maximum value (defaults to \( 1.0 \))

reset()

void gf::Heightmap::reset

(

)

Reset the heightmap.

The values are all set to \( 0.0 \)

scale()

void gf::Heightmap::scale

(

double

value

)

Scale the values of the heightmap.

Parameters

value

The factor of scaling

setValue()

void gf::Heightmap::setValue ( Vector2i  position, double  value  )

inline

Set the value at the specified position.

Parameters

position	A position
value	The new value

subMap()

Heightmap gf::Heightmap::subMap

(

RectI

area

)

const

Get a sub-map of the heightmap.

Parameters

area	The area of the sub-map in the heightmap

thermalErosion()

void gf::Heightmap::thermalErosion	(	unsigned	iterations,
		double	talus,
		double	fraction
	)

Apply thermal erosion to the heightmap.

Parameters

iterations	The number of iterations
talus	The minimum difference for a move of material (typically \( \frac{4}{N} \))
fraction	The fraction of material that moves (typically \( 0.5 \))