forked from TinyTitan/SPH
-
Notifications
You must be signed in to change notification settings - Fork 0
/
hash.c
242 lines (197 loc) · 9.14 KB
/
hash.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
/*
The MIT License (MIT)
Copyright (c) 2014 Adam Simpson
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/
#include "hash.h"
#include "fluid.h"
#include <math.h>
#include <stdbool.h>
#include <string.h>
#include <assert.h>
// Uniform grid hash, this prevents having to check duplicates when inserting
// Fabs needed as neighbor search can go out of bounds
unsigned int hash_val(float x, float y, neighbor_grid_t *grid, param *params)
{
const float spacing = grid->spacing;
// Calculate grid coordinates
unsigned int grid_x,grid_y;
grid_x = floor(x/spacing);
grid_y = floor(y/spacing);
unsigned int grid_position = (grid_y * grid->size_x + grid_x);
return grid_position;
}
// Add halo particles to neighbors array
// We also calculate the density as it's convenient
void hash_halo(fluid_particle **fluid_particle_pointers, neighbor_grid_t *grid, param *params, bool compute_density)
{
int index,i,dx,dy,n, grid_x, grid_y;
float x,y,r2, r;
fluid_particle *h_p, *p;
int n_start = params->number_fluid_particles_local; // Start of halo particles
int n_finish = n_start + params->number_halo_particles; // End of halo particles
float h = params->tunable_params.smoothing_radius;
float h_recip = 1.0f/h;
unsigned int max_neighbors = grid->max_neighbors;
float spacing = grid->spacing;
neighbor *neighbors = grid->neighbors;
bucket_t *grid_buckets = grid->grid_buckets;
float ratio;
float h2 = h*h;
neighbor *ne;
// Loop over each halo particle
for(i=n_start; i<n_finish; i++)
{
// Retrieve hash index for halo particle
h_p = fluid_particle_pointers[i];
// Calculate coordinates within bucket grid
grid_x = floor(h_p->x/spacing);
grid_y = floor(h_p->y/spacing);
// Check neighbors of current bucket
// This only checks 'behind' neighbors as 'forward' neighbors are fluid particles
for (dx=-1; dx<=1; dx++) {
for (dy=-1; dy<=1; dy++) {
// If the neighbor is outside of the grid we don't process it
if ( grid_y+dy < 0 || grid_x+dx < 0 || (grid_x+dx) >= grid->size_x || (grid_y+dy) >= grid->size_y)
continue;
// Calculate index of neighbor cell
index = (grid_y + dy)*grid->size_x + (grid_x + dx);
// Go through each fluid particle, p, in neighbor point bucket
for (n=0; n<grid_buckets[index].number_fluid; n++) {
p = grid_buckets[index].fluid_particles[n];
// Enforce cutoff
r2 = (h_p->x-p->x)*(h_p->x-p->x) + (h_p->y-p->y)*(h_p->y-p->y);
if(r2 > h2)
continue;
// Get neighbor bucket for particle p and add halo particle to it
ne = &neighbors[p->id];
if (ne->number_fluid_neighbors < max_neighbors) {
ne->fluid_neighbors[ne->number_fluid_neighbors++] = h_p;
if(compute_density) {
r = sqrt(r2);
ratio = r*h_recip;
calculate_density(p, h_p, ratio);
}
}
else
debug_print("halo overflowing\n");
}
} // End neighbor search y
} // End neighbor search x
} // End halo particle loop
}
// The following function will fill the i'th neighbor bucket with the i'th fluid_particle_pointers particle neighbors
// Only the forward half of the neighbors are added as the forces are symmetrized.
// We also calculate the density as it's convenient
void hash_fluid(fluid_particle **fluid_particle_pointers, neighbor_grid_t *grid, param *params, bool compute_density)
{
int i,j,dx,dy,n,c;
float x,y, px,py;
float h = params->tunable_params.smoothing_radius;
float h_recip = 1.0f/h;
float h2 = h*h;
int n_f = params->number_fluid_particles_local;
unsigned int max_neighbors = grid->max_neighbors;
unsigned int max_bucket_size = grid->max_bucket_size;
neighbor *neighbors = grid->neighbors;
bucket_t *grid_buckets = grid->grid_buckets;
unsigned int length_hash = grid->size_x * grid->size_y;
fluid_particle *p, *q, *q_neighbor;
neighbor *ne;
float r,r2, ratio;
unsigned int index, neighbor_index;
// zero out number of particles in bucket
for (index=0; index<length_hash; index++){
grid_buckets[index].number_fluid = 0;
}
// First pass - insert fluid particles into hash
for (i=0; i<n_f; i++) {
p = fluid_particle_pointers[i];
neighbors[i].number_fluid_neighbors = 0;
index = hash_val(p->x, p->y, grid, params);
if (grid_buckets[index].number_fluid < max_bucket_size) {
grid_buckets[index].fluid_particles[grid_buckets[index].number_fluid] = p;
grid_buckets[index].number_fluid++;
}
else
debug_print("first pass overflow\n");
}
// Second pass - fill particle neighbors by processing grid of buckets
for (j=0; j<grid->size_y; j++) {
for(i=0; i<grid->size_x; i++) {
index = (j * grid->size_x + i);
if(grid_buckets[index].number_fluid == 0)
continue;
// Process current buckets own particle interactions
// This will only add one neighbor entry per force-pair
for(c=0; c<grid_buckets[index].number_fluid; c++) {
p = grid_buckets[index].fluid_particles[c];
ne = &neighbors[p->id];
for(n=c+1; n<grid_buckets[index].number_fluid; n++) {
q = grid_buckets[index].fluid_particles[n];
// Append q to p's neighbor list
r2 = (p->x-q->x)*(p->x-q->x) + (p->y-q->y)*(p->y-q->y);
if(r2 > h2)
continue;
if(ne->number_fluid_neighbors < max_neighbors) {
ne->fluid_neighbors[ne->number_fluid_neighbors++] = q;
if(compute_density) {
r = sqrt(r2);
ratio = r*h_recip;
calculate_density(p, q, ratio);
}
}
else
debug_print("self bucket overflow\n");
}
}
// Check neighbors of current bucket
// This only checks "forward" neighbors
for (dx=0; dx<=1; dx++) {
for (dy=(dx?-1:1); dy<=1; dy++) {
// If the neighbor is outside of the grid we don't process it
if ( j+dy < 0 || i+dx < 0 || (i+dx) >= grid->size_x || (j+dy) >= grid->size_y)
continue;
neighbor_index = (j+dy)*grid->size_x + (i+dx);
// Add neighbor particles to particles in current bucket
for (c=0; c<grid_buckets[index].number_fluid; c++) {
// Particle in currently being worked on buccket
q = grid_buckets[index].fluid_particles[c];
ne = &neighbors[q->id];
for(n=0; n<grid_buckets[neighbor_index].number_fluid; n++){
// Append neighbor to q's neighbor list
q_neighbor = grid_buckets[neighbor_index].fluid_particles[n];
r2 = (q_neighbor->x-q->x)*(q_neighbor->x-q->x) + (q_neighbor->y-q->y)*(q_neighbor->y-q->y);
if(r2 > h2)
continue;
if(ne->number_fluid_neighbors < max_neighbors) {
ne->fluid_neighbors[ne->number_fluid_neighbors++] = q_neighbor;
if(compute_density) {
r = sqrt(r2);
ratio = r*h_recip;
calculate_density(q_neighbor, q, ratio);
}
}
else
debug_print("neighbor overflow\n");
}
}
} // end dy
} // end dx
} // end grid y
} // end grid x
}// end function