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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.
*
*/
using OpenSim.Region.Environment.Interfaces;
using System;
namespace OpenSim.Region.Environment.Modules.Terrain.PaintBrushes
{
/// <summary>
/// Hydraulic Erosion Brush
/// </summary>
public class ErodeSphere : ITerrainPaintableEffect
{
NeighbourSystem type = NeighbourSystem.Moore; // Parameter
double rainHeight = 0.2;
int rounds = 10;
double waterSaturation = 0.30; // Can carry 1% of water in height
#region Supporting Functions
private enum NeighbourSystem
{
Moore,
VonNeumann
} ;
private int[] Neighbours(NeighbourSystem type, int index)
{
int[] coord = new int[2];
index++;
switch (type)
{
case NeighbourSystem.Moore:
switch (index)
{
case 1:
coord[0] = -1;
coord[1] = -1;
break;
case 2:
coord[0] = -0;
coord[1] = -1;
break;
case 3:
coord[0] = +1;
coord[1] = -1;
break;
case 4:
coord[0] = -1;
coord[1] = -0;
break;
case 5:
coord[0] = -0;
coord[1] = -0;
break;
case 6:
coord[0] = +1;
coord[1] = -0;
break;
case 7:
coord[0] = -1;
coord[1] = +1;
break;
case 8:
coord[0] = -0;
coord[1] = +1;
break;
case 9:
coord[0] = +1;
coord[1] = +1;
break;
default:
break;
}
break;
case NeighbourSystem.VonNeumann:
switch (index)
{
case 1:
coord[0] = 0;
coord[1] = -1;
break;
case 2:
coord[0] = -1;
coord[1] = 0;
break;
case 3:
coord[0] = +1;
coord[1] = 0;
break;
case 4:
coord[0] = 0;
coord[1] = +1;
break;
case 5:
coord[0] = -0;
coord[1] = -0;
break;
default:
break;
}
break;
}
return coord;
}
private double SphericalFactor(double x, double y, double rx, double ry, double size)
{
double z = size * size - ((x - rx) * (x - rx) + (y - ry) * (y - ry));
return z;
}
private double GetBilinearInterpolate(double x, double y, ITerrainChannel map)
{
int w = map.Width;
int h = map.Height;
if (x > w - 2.0)
x = w - 2.0;
if (y > h - 2.0)
y = h - 2.0;
if (x < 0.0)
x = 0.0;
if (y < 0.0)
y = 0.0;
int stepSize = 1;
double h00 = map[(int)x, (int)y];
double h10 = map[(int)x + stepSize, (int)y];
double h01 = map[(int)x, (int)y + stepSize];
double h11 = map[(int)x + stepSize, (int)y + stepSize];
double h1 = h00;
double h2 = h10;
double h3 = h01;
double h4 = h11;
double a00 = h1;
double a10 = h2 - h1;
double a01 = h3 - h1;
double a11 = h1 - h2 - h3 + h4;
double partialx = x - (int)x;
double partialz = y - (int)y;
double hi = a00 + (a10 * partialx) + (a01 * partialz) + (a11 * partialx * partialz);
return hi;
}
#endregion
#region ITerrainPaintableEffect Members
public void PaintEffect(ITerrainChannel map, double rx, double ry, double strength, double duration)
{
int x, y;
// Using one 'rain' round for this, so skipping a useless loop
// Will need to adapt back in for the Flood brush
ITerrainChannel water = new TerrainChannel(map.Width, map.Height);
ITerrainChannel sediment = new TerrainChannel(map.Width, map.Height);
// Fill with rain
for (x = 0; x < water.Width; x++)
for (y = 0; y < water.Height; y++)
water[x, y] = Math.Max(0.0, SphericalFactor(x, y, rx, ry, strength) * rainHeight * duration);
for (int i = 0; i < rounds; i++)
{
// Erode underlying terrain
for (x = 0; x < water.Width; x++)
{
for (y = 0; y < water.Height; y++)
{
double solConst = (1.0 / rounds);
double sedDelta = water[x, y] * solConst;
map[x, y] -= sedDelta;
sediment[x, y] += sedDelta;
}
}
// Move water
for (x = 0; x < water.Width; x++)
{
for (y = 0; y < water.Height; y++)
{
if (water[x, y] <= 0)
continue;
// Step 1. Calculate average of neighbours
int neighbours = 0;
double altitudeTotal = 0.0;
double altitudeMe = map[x, y] + water[x, y];
int NEIGHBOUR_ME = 4;
int NEIGHBOUR_MAX = type == NeighbourSystem.Moore ? 9 : 5;
for (int j = 0; j < NEIGHBOUR_MAX; j++)
{
if (j != NEIGHBOUR_ME)
{
int[] coords = Neighbours(type, j);
coords[0] += x;
coords[1] += y;
if (coords[0] > map.Width - 1)
continue;
if (coords[1] > map.Height - 1)
continue;
if (coords[0] < 0)
continue;
if (coords[1] < 0)
continue;
// Calculate total height of this neighbour
double altitudeNeighbour = water[coords[0], coords[1]] + map[coords[0], coords[1]];
// If it's greater than me...
if (altitudeNeighbour - altitudeMe < 0)
{
// Add it to our calculations
neighbours++;
altitudeTotal += altitudeNeighbour;
}
}
}
if (neighbours == 0)
continue;
double altitudeAvg = altitudeTotal / neighbours;
// Step 2. Allocate water to neighbours.
for (int j = 0; j < NEIGHBOUR_MAX; j++)
{
if (j != NEIGHBOUR_ME)
{
int[] coords = Neighbours(type, j);
coords[0] += x;
coords[1] += y;
if (coords[0] > map.Width - 1)
continue;
if (coords[1] > map.Height - 1)
continue;
if (coords[0] < 0)
continue;
if (coords[1] < 0)
continue;
// Skip if we dont have water to begin with.
if (water[x, y] < 0)
continue;
// Calculate our delta average
double altitudeDelta = altitudeMe - altitudeAvg;
if (altitudeDelta < 0)
continue;
// Calculate how much water we can move
double waterMin = Math.Min(water[x, y], altitudeDelta);
double waterDelta = waterMin * ((water[coords[0], coords[1]] + map[coords[0], coords[1]])
/ altitudeTotal);
double sedimentDelta = sediment[x, y] * (waterDelta / water[x, y]);
if (sedimentDelta > 0)
{
sediment[x, y] -= sedimentDelta;
sediment[coords[0], coords[1]] += sedimentDelta;
}
}
}
}
}
// Evaporate
for (x = 0; x < water.Width; x++)
{
for (y = 0; y < water.Height; y++)
{
water[x, y] *= 1.0 - (rainHeight / rounds);
double waterCapacity = waterSaturation * water[x, y];
double sedimentDeposit = sediment[x, y] - waterCapacity;
if (sedimentDeposit > 0)
{
sediment[x, y] -= sedimentDeposit;
map[x, y] += sedimentDeposit;
}
}
}
}
// Deposit any remainder (should be minimal)
for (x = 0; x < water.Width; x++)
for (y = 0; y < water.Height; y++)
if (sediment[x, y] > 0)
map[x, y] += sediment[x, y];
}
#endregion
}
}
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