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/*
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following
disclaimer in the documentation and/or other materials provided
with the distribution.
* Neither the name of libTerrain nor the names of
its contributors may be used to endorse or promote products
derived from this software without specific prior written
permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
using System;
using System.Collections.Generic;
using System.Text;
namespace libTerrain
{
partial class Channel
{
/// <summary>
/// A thermal weathering implementation based on Musgrave's original 1989 algorithm. This is Adam's custom implementation which may differ slightly from the original.
/// </summary>
/// <param name="talus">The rock angle (represented as a dy/dx ratio) at which point it will be succeptible to breakage</param>
/// <param name="rounds">The number of erosion rounds</param>
/// <param name="c">The amount of rock to carry each round</param>
public Channel thermalWeathering(double talus, int rounds, double c)
{
double[,] lastFrame;
double[,] thisFrame;
lastFrame = (double[,])map.Clone();
thisFrame = (double[,])map.Clone();
NEIGHBOURS type = NEIGHBOURS.NEIGHBOUR_MOORE; // Using moore neighbourhood (twice as computationally expensive)
int NEIGHBOUR_ME = 4; // I am always 4 in both systems.
int NEIGHBOUR_MAX = type == NEIGHBOURS.NEIGHBOUR_MOORE ? 9 : 5;
int frames = rounds; // Number of thermal erosion iterations to run
int i, j;
int x, y;
for (i = 0; i < frames; i++)
{
for (x = 0; x < w; x++)
{
for (y = 0; y < h; y++)
{
for (j = 0; j < NEIGHBOUR_MAX; j++)
{
if (j != NEIGHBOUR_ME)
{
int[] coords = neighbours(type, j);
coords[0] += x;
coords[1] += y;
if (coords[0] > w - 1)
coords[0] = w - 1;
if (coords[1] > h - 1)
coords[1] = h - 1;
if (coords[0] < 0)
coords[0] = 0;
if (coords[1] < 0)
coords[1] = 0;
double heightF = thisFrame[x, y];
double target = thisFrame[coords[0], coords[1]];
if (target > heightF + talus)
{
double calc = c * ((target - heightF) - talus);
heightF += calc;
target -= calc;
}
thisFrame[x, y] = heightF;
thisFrame[coords[0], coords[1]] = target;
}
}
}
}
lastFrame = (double[,])thisFrame.Clone();
}
map = thisFrame;
normalise(); // Just to guaruntee a smooth 0..1 value
return this;
}
}
}
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