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/*
* Copyright (c) Contributors, http://www.openmetaverse.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.
*
*/
using System;
using System.Collections.Generic;
using System.Text;
namespace libTerrain
{
partial class Channel
{
public void HydraulicErosion(Channel rain, double evaporation, double solubility, int frequency, int rounds)
{
SetDiff();
Channel water = new Channel(w, h);
Channel sediment = new Channel(w, h);
Channel terrain = this;
Channel waterFlow = new Channel(w, h);
NeighbourSystem type = NeighbourSystem.Moore;
int NEIGHBOUR_ME = 4;
int NEIGHBOUR_MAX = type == NeighbourSystem.Moore ? 9 : 5;
for (int i = 0; i < rounds; i++)
{
water += rain;
sediment = terrain * water;
terrain -= sediment;
for (int x = 1; x < w - 1; x++)
{
for (int y = 1; y < h - 1; y++)
{
double[] heights = new double[NEIGHBOUR_MAX];
double[] diffs = new double[NEIGHBOUR_MAX];
double heightCenter = map[x, y];
for (int j = 0; j < NEIGHBOUR_MAX; j++)
{
if (j != NEIGHBOUR_ME)
{
int[] coords = Neighbours(type, j);
coords[0] += x;
coords[1] += y;
heights[j] = map[coords[0], coords[1]] + water.map[coords[0], coords[1]] + sediment.map[coords[0], coords[1]];
diffs[j] = heightCenter - heights[j];
}
}
double totalHeight = 0;
double totalHeightDiff = 0;
int totalCellsCounted = 1;
for (int j = 0; j < NEIGHBOUR_MAX; j++)
{
if (j != NEIGHBOUR_ME)
{
if (diffs[j] > 0)
{
totalHeight += heights[j];
totalHeightDiff += diffs[j];
totalCellsCounted++;
}
}
}
if (totalCellsCounted == 1)
continue;
double averageHeight = totalHeight / totalCellsCounted;
double waterAmount = Math.Min(water.map[x, y], heightCenter - averageHeight);
// TODO: Check this.
waterFlow.map[x, y] += waterFlow.map[x, y] - waterAmount;
double totalInverseDiff = waterAmount / totalHeightDiff;
for (int j = 0; j < NEIGHBOUR_MAX; j++)
{
if (j != NEIGHBOUR_ME)
{
int[] coords = Neighbours(type, j);
coords[0] += x;
coords[1] += y;
if (diffs[j] > 0)
{
waterFlow.SetWrap(coords[0], coords[1], waterFlow.map[coords[0], coords[1]] + diffs[j] * totalInverseDiff);
}
}
}
}
}
water += waterFlow;
waterFlow.Fill(0);
water *= evaporation;
for (int x = 0; x < w; x++)
{
for (int y = 0; y < h; y++)
{
double deposition = sediment.map[x, y] - water.map[x, y] * solubility;
if (deposition > 0)
{
sediment.map[x, y] -= deposition;
terrain.map[x, y] += deposition;
}
}
}
}
}
}
}
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