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authorAdam Frisby2007-07-22 02:06:46 +0000
committerAdam Frisby2007-07-22 02:06:46 +0000
commit3f8b609831b49a332371de1cbd9aabbbc95b5b58 (patch)
tree56ce99fb9a683aa704548e8402cc76dc74d2fa22 /OpenSim/Region/Terrain.BasicTerrain
parent* Patched runprebuild.sh for *nix systems which do not register a mono ABI ha... (diff)
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* Ported Jos Stam's Navier Stokes algorithm from his GDC2003 Paper to C# and included in libTerrain - May I never have to do that again.
Diffstat (limited to 'OpenSim/Region/Terrain.BasicTerrain')
-rw-r--r--OpenSim/Region/Terrain.BasicTerrain/libTerrainBSD/Channel/Manipulators/NavierStokes.cs214
1 files changed, 214 insertions, 0 deletions
diff --git a/OpenSim/Region/Terrain.BasicTerrain/libTerrainBSD/Channel/Manipulators/NavierStokes.cs b/OpenSim/Region/Terrain.BasicTerrain/libTerrainBSD/Channel/Manipulators/NavierStokes.cs
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+++ b/OpenSim/Region/Terrain.BasicTerrain/libTerrainBSD/Channel/Manipulators/NavierStokes.cs
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1/*
2* Copyright (c) Contributors, http://www.openmetaverse.org/
3* See CONTRIBUTORS.TXT for a full list of copyright holders.
4*
5* Redistribution and use in source and binary forms, with or without
6* modification, are permitted provided that the following conditions are met:
7* * Redistributions of source code must retain the above copyright
8* notice, this list of conditions and the following disclaimer.
9* * Redistributions in binary form must reproduce the above copyright
10* notice, this list of conditions and the following disclaimer in the
11* documentation and/or other materials provided with the distribution.
12* * Neither the name of the OpenSim Project nor the
13* names of its contributors may be used to endorse or promote products
14* derived from this software without specific prior written permission.
15*
16* THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS AND ANY
17* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19* DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
20* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
23* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
25* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26*
27*/
28
29using System;
30using System.Collections.Generic;
31using System.Text;
32
33namespace libTerrain
34{
35 partial class Channel
36 {
37 // Navier Stokes Algorithms ported from
38 // "Real-Time Fluid Dynamics for Games" by Jos Stam.
39 // presented at GDC 2003.
40
41 // Poorly ported from C++. (I gave up making it properly native somewhere after nsSetBnd)
42
43 private static int nsIX(int i, int j, int N)
44 {
45 return ((i) + (N + 2) * (j));
46 }
47
48 private static void nsSwap(ref double x0, ref double x)
49 {
50 double tmp = x0;
51 x0 = x;
52 x = tmp;
53 }
54
55 private static void nsSwap(ref double[] x0, ref double[] x)
56 {
57 double[] tmp = x0;
58 x0 = x;
59 x = tmp;
60 }
61
62 private void nsAddSource(int N, ref double[] x, ref double[] s, double dt)
63 {
64 int i;
65 int size = (N + 2) * (N + 2);
66 for (i = 0; i < size; i++)
67 {
68 x[i] += dt * s[i];
69 }
70 }
71
72 private void nsSetBnd(int N, int b, ref double[] x)
73 {
74 int i;
75 for (i = 0; i <= N; i++)
76 {
77 x[nsIX(0, i, N)] = b == 1 ? -x[nsIX(1, i, N)] : x[nsIX(1, i, N)];
78 x[nsIX(0, N + 1, N)] = b == 1 ? -x[nsIX(N, i, N)] : x[nsIX(N, i, N)];
79 x[nsIX(i, 0, N)] = b == 2 ? -x[nsIX(i, 1, N)] : x[nsIX(i, 1, N)];
80 x[nsIX(i, N + 1, N)] = b == 2 ? -x[nsIX(i, N, N)] : x[nsIX(i, N, N)];
81 }
82 x[nsIX(0, 0, N)] = 0.5f * (x[nsIX(1, 0, N)] + x[nsIX(0, 1, N)]);
83 x[nsIX(0, N + 1, N)] = 0.5f * (x[nsIX(1, N + 1, N)] + x[nsIX(0, N, N)]);
84 x[nsIX(N + 1, 0, N)] = 0.5f * (x[nsIX(N, 0, N)] + x[nsIX(N + 1, 1, N)]);
85 x[nsIX(N + 1, N + 1, N)] = 0.5f * (x[nsIX(N, N + 1, N)] + x[nsIX(N + 1, N, N)]);
86 }
87
88 private void nsLinSolve(int N, int b, ref double[] x, ref double[] x0, double a, double c)
89 {
90 int i, j;
91 for (i = 1; i <= N; i++)
92 {
93 for (j = 1; j <= N; j++)
94 {
95 x[nsIX(i, j, N)] = (x0[nsIX(i, j, N)] + a *
96 (x[nsIX(i - 1, j, N)] +
97 x[nsIX(i + 1, j, N)] +
98 x[nsIX(i, j - 1, N)] + x[nsIX(i, j + 1, N)])
99 ) / c;
100 }
101 }
102
103 nsSetBnd(N, b, ref x);
104 }
105
106 private void nsDiffuse(int N, int b, ref double[] x, ref double[] x0, double diff, double dt)
107 {
108 double a = dt * diff * N * N;
109 nsLinSolve(N, b, ref x, ref x0, a, 1 + 4 * a);
110 }
111
112 private void nsAdvect(int N, int b, ref double[] d, ref double[] d0, ref double[] u, ref double[] v, double dt)
113 {
114 int i, j, i0, j0, i1, j1;
115 double x, y, s0, t0, s1, t1, dt0;
116
117 dt0 = dt * N;
118
119 for (i = 1; i <= N; i++)
120 {
121 for (j = 1; j <= N; j++)
122 {
123 x = i - dt0 * u[nsIX(i, j, N)];
124 y = j - dt0 * v[nsIX(i, j, N)];
125
126 if (x < 0.5)
127 x = 0.5;
128 if (x > N + 0.5)
129 x = N + 0.5;
130 i0 = (int)x;
131 i1 = i0 + 1;
132
133 if (y < 0.5)
134 y = 0.5;
135 if (y > N + 0.5)
136 y = N + 0.5;
137 j0 = (int)y;
138 j1 = j0 + 1;
139
140 s1 = x - i0;
141 s0 = 1 - s1;
142 t1 = y - j0;
143 t0 = 1 - t1;
144
145 d[nsIX(i, j, N)] = s0 * (t0 * d0[nsIX(i0, j0, N)] + t1 * d0[nsIX(i0, j1, N)]) +
146 s1 * (t0 * d0[nsIX(i1, j0, N)] + t1 * d0[nsIX(i1, j1, N)]);
147 }
148 }
149
150 nsSetBnd(N, b, ref d);
151 }
152
153 public void nsProject(int N, ref double[] u, ref double[] v, ref double[] p, ref double[] div)
154 {
155 int i, j;
156
157 for (i = 1; i <= N; i++)
158 {
159 for (j = 1; j <= N; j++)
160 {
161 div[nsIX(i, j, N)] = -0.5 * (u[nsIX(i + 1, j, N)] - u[nsIX(i - 1, j, N)] + v[nsIX(i, j + 1, N)] - v[nsIX(i, j - 1, N)]) / N;
162 p[nsIX(i, j, N)] = 0;
163 }
164 }
165
166 nsSetBnd(N, 0, ref div);
167 nsSetBnd(N, 0, ref p);
168
169 nsLinSolve(N, 0, ref p, ref div, 1, 4);
170
171 for (i = 1; i <= N; i++)
172 {
173 for (j = 1; j <= N; j++)
174 {
175 u[nsIX(i, j, N)] -= 0.5 * N * (p[nsIX(i + 1, j, N)] - p[nsIX(i - 1, j, N)]);
176 v[nsIX(i, j, N)] -= 0.5 * N * (p[nsIX(i, j + 1, N)] - p[nsIX(i, j - 1, N)]);
177 }
178 }
179
180 nsSetBnd(N, 1, ref u);
181 nsSetBnd(N, 2, ref v);
182 }
183
184 private void nsDensStep(int N, ref double[] x, ref double[] x0, ref double[] u, ref double[] v, double diff, double dt)
185 {
186 nsAddSource(N, ref x, ref x0, dt);
187 nsSwap(ref x0, ref x);
188 nsDiffuse(N, 0, ref x, ref x0, diff, dt);
189 nsSwap(ref x0, ref x);
190 nsAdvect(N, 0, ref x, ref x0, ref u, ref v, dt);
191 }
192
193 private void nsVelStep(int N, ref double[] u, ref double[] v, ref double[] u0, ref double[] v0, double visc, double dt)
194 {
195 nsAddSource(N, ref u, ref u0, dt);
196 nsAddSource(N, ref v, ref v0, dt);
197 nsSwap(ref u0, ref u);
198 nsDiffuse(N, 1, ref u, ref u0, visc, dt);
199 nsSwap(ref v0, ref v);
200 nsDiffuse(N, 2, ref v, ref v0, visc, dt);
201 nsProject(N, ref u, ref v, ref u0, ref v0);
202 nsSwap(ref u0, ref u);
203 nsSwap(ref v0, ref v);
204 nsAdvect(N, 1, ref u, ref u0, ref u0, ref v0, dt);
205 nsAdvect(N, 2, ref v, ref v0, ref u0, ref v0, dt);
206 nsProject(N, ref u, ref v, ref u0, ref v0);
207 }
208
209 public void navierSimulate()
210 {
211
212 }
213 }
214} \ No newline at end of file
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