< index
< 15. Heightmap toolkit
< 15.2 Basic operations

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15.3 Modifying the heightmap
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Those are advanced operations involving several or all map cells.
15.3.1 Add hills
15.3.2 Dig hills
15.3.3 Simulate rain erosion
15.3.4 Do a generic transformation
15.3.5 Add a Voronoi diagram
15.3.6 Add a fbm
15.3.7 Scale with a fbm
15.3.8 Dig along a Bezier curve

15.3.1 Add hills

This function adds a hill (a half spheroid) at given position.

C++ : void TCODHeightmap::addHill(float x, float y, float radius, float height)
C   : void TCOD_heightmap_add_hill(TCOD_heightmap_t *hm, float x, float y, float radius, float height)
Py  : heightmap_add_hill(hm, x, y, radius, height)

Parameter	Description
hm	In the C version, the address of the heightmap struct returned by the creation function.
x,y	Coordinates of the center of the hill. 0 <= x < map width 0 <= y < map height
radius	The hill radius.
height	The hill height. If height == radius or -radius, the hill is a half-sphere.

15.3.2 Dig hills

This function takes the highest value (if height > 0) or the lowest (if height < 0) between the map and the hill.
It's main goal is to carve things in maps (like rivers) by digging hills along a curve.

C++ : void TCODHeightmap::digHill(float hx, float hy, float hradius, float height)
C   : void TCOD_heightmap_dig_hill(TCOD_heightmap_t *hm, float x, float y, float radius, float height)
Py  : heightmap_dig_hill(hm, x, y, radius, height)

Parameter	Description
hm	In the C version, the address of the heightmap struct returned by the creation function.
x,y	Coordinates of the center of the hill. 0 <= x < map width 0 <= y < map height
radius	The hill radius.
height	The hill height. Can be < 0 or > 0

15.3.3 Simulate rain erosion

This function simulates the effect of rain drops on the terrain, resulting in erosion patterns.

C++ : void TCODHeightmap::rainErosion(int nbDrops,float erosionCoef,float sedimentationCoef,TCODRandom *rnd)
C   : void TCOD_heightmap_rain_erosion(TCOD_heightmap_t *hm, int nbDrops,float erosionCoef,float sedimentationCoef,TCOD_random_t rnd)
Py  : heightmap_rain_erosion(hm, nbDrops,erosionCoef,sedimentationCoef,rnd=0)

Parameter	Description
hm	In the C version, the address of the heightmap struct returned by the creation function.
nbDrops	Number of rain drops to simulate. Should be at least width * height.
erosionCoef	Amount of ground eroded on the drop's path.
sedimentationCoef	Amount of ground deposited when the drops stops to flow
rnd	RNG to use, NULL for default generator.

15.3.4 Do a generic transformation

This function allows you to apply a generic transformation on the map, so that each resulting cell value is the weighted sum of several neighbour cells. This can be used to smooth/sharpen the map.

C++ : void TCODHeightmap::kernelTransform(int kernelSize, int *dx, int *dy, float *weight, float minLevel,float maxLevel)
C   : void TCOD_heightmap_kernel_transform(TCOD_heightmap_t *hm, int kernelsize, int *dx, int *dy, float *weight, float minLevel,float maxLevel)
Py  : heightmap_kernel_transform(hm, kernelsize, dx, dy, weight, minLevel,maxLevel)

Parameter	Description
hm	In the C version, the address of the heightmap struct returned by the creation function.
kernelSize	Number of neighbour cells involved.
dx,dy	Array of kernelSize cells coordinates. The coordinates are relative to the current cell (0,0) is current cell, (-1,0) is west cell, (0,-1) is north cell, (1,0) is east cell, (0,1) is south cell, ...
weight	Array of kernelSize cells weight. The value of each neighbour cell is scaled by its corresponding weight
minLevel	The transformation is only applied to cells which value is >= minLevel.
maxLevel	The transformation is only applied to cells which value is <= maxLevel.

15.3.5 Add a Voronoi diagram

This function adds values from a Voronoi diagram to the map.

C++ : void TCODHeightmap::addVoronoi(int nbPoints, int nbCoef, float *coef,TCODRandom *rnd)
C   : void TCOD_heightmap_add_voronoi(TCOD_heightmap_t *hm, int nbPoints, int nbCoef, float *coef,TCOD_random_t rnd)
Py  : heightmap_add_voronoi(hm, nbPoints, nbCoef, coef,rnd=0)

Parameter	Description
hm	In the C version, the address of the heightmap struct returned by the creation function.
nbPoints	Number of Voronoi sites.
nbCoef	The diagram value is calculated from the nbCoef closest sites.
coef	The distance to each site is scaled by the corresponding coef. Closest site : coef[0], second closest site : coef[1], ...
rnd	RNG to use, NULL for default generator.

15.3.6 Add a fbm

This function adds values from a simplex fbm function to the map.

C++ : void TCODHeightmap::addFbm(TCODNoise *noise,float mulx, float muly, float addx, float addy, float octaves, float delta, float scale)
C   : void TCOD_heightmap_add_fbm(TCOD_heightmap_t *hm, TCOD_noise_t noise,float mulx, float muly, float addx, float addy, float octaves, float delta, float scale)
Py  : heightmap_add_fbm(hm, noise,mulx, muly, addx, addy, octaves, delta, scale)

Parameter	Description
hm	In the C version, the address of the heightmap struct returned by the creation function.
noise	The 2D noise to use.
mulx, muly / addx, addy	The noise coordinate for map cell (x,y) are (x + addx)mulx / width , (y + addy)muly / height. Those values allow you to scale and translate the noise function over the heightmap.
octaves	Number of octaves in the fbm sum.
delta / scale	The value added to the heightmap is delta + noise * scale. noise is between -1.0 and 1.0

15.3.7 Scale with a fbm

This function works exactly as the previous one, but it multiplies the resulting value instead of adding it to the heightmap.

C++ : void TCODHeightmap::scaleFbm(TCODNoise *noise,float mulx, float muly, float addx, float addy, float octaves, float delta, float scale)
C   : void TCOD_heightmap_scale_fbm(TCOD_heightmap_t *hm, TCOD_noise_t noise,float mulx, float muly, float addx, float addy, float octaves, float delta, float scale)
Py  : heightmap_scale_fbm(hm, noise,mulx, muly, addx, addy, octaves, delta, scale)

15.3.8 Dig along a Bezier curve

This function carve a path along a cubic Bezier curve using the digHill function.
Could be used for roads/rivers/...
Both radius and depth can vary linearly along the path.

C++ : void TCODHeightmap::digBezier(int px[4], int py[4], float startRadius, float startDepth, float endRadius, float endDepth)
C   : void TCOD_heightmap_dig_bezier(TCOD_heightmap_t *hm, int px[4], int py[4], float startRadius, float startDepth, float endRadius, float endDepth)
Py  : heightmap_dig_bezier(hm, px, py,  startRadius,  startDepth, endRadius, endDepth)

Parameter	Description
hm	In the C version, the address of the heightmap struct returned by the creation function.
px,py	The coordinates of the 4 Bezier control points.
startRadius	The path radius in map cells at point P0. Might be < 1.0
startDepth	The path depth at point P0.
endRadius	The path radius in map cells at point P3. Might be < 1.0
endDepth	The path depth at point P3.

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