Perform filtering on a terrain height field. More...

#include <TerrainFilters.h>

Public Types
enum	MergeOperation { Addition =0, Subtract, Multiplication, Division, Minimum, Maximum }
	used in the merge function

enum	FlattenOperation { Fill_Op, ShaveTop_Op, Flatten_Op }

Public Member Functions
TTerrain *	GetTerrainData ()
	get the terrain data that is associated with this filter. More...

void	Flatten (FlattenOperation flatten_op, float elevation, float factor, float center_x, float center_y, float radius)
	Flatten the terrain both up and down to the specified elevation, using using the tightness parameter to determine how much the altered points are allowed to deviate from the specified elevation. More...

void	RadialScale (float center_x, float center_y, float scale_factor, float min_dist, float max_dist, float smooth_factor, int frequency)
	Note: terrain data should be in normalized space with height in the range [0,1]. More...

void	GaussianHill (float x, float y, float radius, float hscale, float standard_deviation, float smooth_factor)

void	Spherical (float offset)
	offset in a spherical region

void	Roughen_Smooth (bool roughen, bool big_grid, float factor)
	square filter for sharpening and smoothing. More...

void	Ramp (float x1, float y1, float height1, float x2, float y2, float height2, float radius, float borderpercentage=0.5f, float factor=1.0f)
	create a ramp (inclined slope) from height(x1,y1) to height(x2,y2). More...

void	SetConstEdgeHeight (float fHeight=0, int nSmoothPixels=7)
	load height field from file More...

void	Merge (TTerrain terrain_1, TTerrain terrain_2, float weight_1, float weight_2, MergeOperation operation)
	merge two terrains, and save the result to the current terrain. More...

Static Public Member Functions
static float	grid_neighbour_sum_size (TTerrain *terrain, int x, int y, int size)

static float	grid_neighbour_average_size (TTerrain *terrain, int x, int y, int size)

Detailed Description

Perform filtering on a terrain height field.

set or get the terrain data by calling GetTerrainData() function.

Member Enumeration Documentation

§ FlattenOperation

enum ParaEngine::CTerrainFilters::FlattenOperation

Enumerator
Fill_Op	Flatten the terrain up to the specified elevation.
ShaveTop_Op	Flatten the terrain down to the specified elevation.
Flatten_Op	Flatten the terrain up and down to the specified elevation.

Member Function Documentation

§ Flatten()

void CTerrainFilters::Flatten	(	FlattenOperation	flatten_op,
		float	elevation,
		float	factor,
		float	center_x,
		float	center_y,
		float	radius
	)

Flatten the terrain both up and down to the specified elevation, using using the tightness parameter to determine how much the altered points are allowed to deviate from the specified elevation.

Parameters

elevation	the desired height
factor	value is between [0,1]. 1 means fully transformed; 0 means nothing is changed
center_x	the center of the affected circle. value in the range [0,1]
center_y	the center of the affected circle.value in the range [0,1]
radius	the radius of the affected circle.value in the range [0,0.5]

§ GetTerrainData()

TTerrain * CTerrainFilters::GetTerrainData ( )

get the terrain data that is associated with this filter.

The user can read from or write to this terrain data.

§ Merge()

void CTerrainFilters::Merge	(	TTerrain *	terrain_1,
		TTerrain *	terrain_2,
		float	weight_1,
		float	weight_2,
		MergeOperation	operation
	)

merge two terrains, and save the result to the current terrain.

The three terrains are aligned by their center. the input terrain can be the current terrain. The two input terrain must not be normalized.

§ RadialScale()

void CTerrainFilters::RadialScale	(	float	center_x,
		float	center_y,
		float	scale_factor,
		float	min_dist,
		float	max_dist,
		float	smooth_factor,
		int	frequency
	)

Note: terrain data should be in normalized space with height in the range [0,1].

Picks a point and scales the surrounding terrain in a circular manner. Can be used to make all sorts of circular shapes. Still needs some work. radial_scale: pick a point (center_x, center_y) and scale the points where distance is mindist<=distance<=maxdist linearly. The formula we'll use for a nice sloping smoothing factor is (-cos(x*3)/2)+0.5.

§ Ramp()

void ParaEngine::CTerrainFilters::Ramp	(	float	x1,
		float	y1,
		float	height1,
		float	x2,
		float	y2,
		float	height2,
		float	radius,
		float	borderpercentage = `0.5f`,
		float	factor = `1.0f`
	)

create a ramp (inclined slope) from height(x1,y1) to height(x2,y2).

create a ramp : inclined slope LiXizhi 2009.1.30

The ramp's half width is radius. this is usually used to created a slope path connecting a high land with a low land.

Parameters

radius	The ramp's half width
borderpercentage	borderpercentage*radius is how long the ramp boarder is to linearly interpolate with the original terrain. specify 0 for sharp ramp border.
factor	in range[0,1]. it is the smoothness to merge with other border heights.Specify 1.0 for a complete merge

Let the point be C (Cx,Cy) and the line be AB (Ax,Ay) to (Bx,By). The length of the line segment AB is L:

L= sqrt( (Bx-Ax)^2 + (By-Ay)^2 ) .Let P be the point of perpendicular projection of C onto AB. Let r be a parameter to indicate P's location along the line containing AB, with the following meaning:

r=0 P = A r=1 P = B r<0 P is on the backward extension of AB r>1 P is on the forward extension of AB 0<r<1 P is interior to ABCompute r with this:

 (Ay-Cy)(Ay-By)-(Ax-Cx)(Bx-Ax)

r = ----------------------------- L^2

Use another parameter s to indicate the location along PC, with the following meaning:

s<0 C is left of AB s>0 C is right of AB s=0 C is on ABCompute s as follows:

  (Ay-Cy)(Bx-Ax)-(Ax-Cx)(By-Ay)

s = --------------------------— L^2

§ Roughen_Smooth()

void CTerrainFilters::Roughen_Smooth	(	bool	roughen,
		bool	big_grid,
		float	factor
	)

square filter for sharpening and smoothing.

Use neighbour-averaging to roughen or smooth the height field. The factor determines how much of the computed roughening is actually applied to the height field. In it's default invocation, the 4 directly neighboring squares are used to calculate the roughening. If you select big sampling grid, all 8 neighboring cells will be used.

Parameters

roughen	true for sharpening, false for smoothing.
big_grid	true for 8 neighboring cells, false for 4.
factor	value is between [0,1]. 1 means fully transformed; 0 means nothing is changed

§ SetConstEdgeHeight()

void CTerrainFilters::SetConstEdgeHeight	(	float	fHeight = `0`,
		int	nSmoothPixels = `7`
	)

load height field from file

Parameters

fHeight : height of the edge

nSmoothPixels

the number of pixels to smooth from the edge of the height field. if this is 0, the original height field will be loaded unmodified. if it is greater than 0, the loaded height field will be smoothed for nSmoothPixels from the edge, where the edge is always fHeight. The smooth function is linear. For example,

0% of original height for the first pixel from the edge
1/nSmoothPixels of original height for the second pixel from the edge. Lerp(1/nSmoothPixels, fheight, currentHeight)
2/nSmoothPixels of original height for the third.Lerp(2/nSmoothPixels, fheight, currentHeight )
100% for the nSmoothPixels-1 pixel

The documentation for this class was generated from the following files:

Client/trunk/ParaEngineClient/terrain/TerrainFilters.h
Client/trunk/ParaEngineClient/terrain/TerrainFilters.cpp

Public Types

Public Member Functions

Static Public Member Functions

Detailed Description

Member Enumeration Documentation

§ FlattenOperation

Member Function Documentation

§ Flatten()

§ GetTerrainData()

§ Merge()

§ RadialScale()

§ Ramp()

§ Roughen_Smooth()

§ SetConstEdgeHeight()