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/*
* Copyright (c) Contributors, http://opensimulator.org/
* See CONTRIBUTORS.TXT for a full list of copyright holders.
*
* 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 the OpenSim Project 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 DEVELOPERS ``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 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.
*/
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)
{
SetDiff();
double[,] lastFrame;
double[,] thisFrame;
lastFrame = (double[,]) map.Clone();
thisFrame = (double[,]) map.Clone();
NeighbourSystem type = NeighbourSystem.Moore;
// Using moore neighbourhood (twice as computationally expensive)
int NEIGHBOUR_ME = 4; // I am always 4 in both systems.
int NEIGHBOUR_MAX = type == NeighbourSystem.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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