| 1 |
/* |
| 2 |
====================================================================== |
| 3 |
In-core kd-tree for photon map |
| 4 |
|
| 5 |
Roland Schregle (roland.schregle@{hslu.ch, gmail.com}) |
| 6 |
(c) Fraunhofer Institute for Solar Energy Systems, |
| 7 |
(c) Lucerne University of Applied Sciences and Arts, |
| 8 |
supported by the Swiss National Science Foundation (SNSF, #147053) |
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====================================================================== |
| 10 |
|
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$Id: pmapkdt.c,v 1.2 2017/08/14 21:12:10 rschregle Exp $ |
| 12 |
*/ |
| 13 |
|
| 14 |
|
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|
| 16 |
#include "pmapdata.h" /* Includes pmapkdt.h */ |
| 17 |
#include "source.h" |
| 18 |
|
| 19 |
|
| 20 |
|
| 21 |
|
| 22 |
void kdT_Null (PhotonKdTree *kdt) |
| 23 |
{ |
| 24 |
kdt -> nodes = NULL; |
| 25 |
} |
| 26 |
|
| 27 |
|
| 28 |
|
| 29 |
static unsigned long kdT_MedianPartition (const Photon *heap, |
| 30 |
unsigned long *heapIdx, |
| 31 |
unsigned long *heapXdi, |
| 32 |
unsigned long left, |
| 33 |
unsigned long right, unsigned dim) |
| 34 |
/* Returns index to median in heap from indices left to right |
| 35 |
(inclusive) in dimension dim. The heap is partitioned relative to |
| 36 |
median using a quicksort algorithm. The heap indices in heapIdx are |
| 37 |
sorted rather than the heap itself. */ |
| 38 |
{ |
| 39 |
const float *p; |
| 40 |
unsigned long l, r, lg2, n2, m, n = right - left + 1; |
| 41 |
unsigned d; |
| 42 |
|
| 43 |
/* Round down n to nearest power of 2 */ |
| 44 |
for (lg2 = 0, n2 = n; n2 > 1; n2 >>= 1, ++lg2); |
| 45 |
n2 = 1 << lg2; |
| 46 |
|
| 47 |
/* Determine median position; this takes into account the fact that |
| 48 |
only the last level in the heap can be partially empty, and that |
| 49 |
it fills from left to right */ |
| 50 |
m = left + ((n - n2) > (n2 >> 1) - 1 ? n2 - 1 : n - (n2 >> 1)); |
| 51 |
|
| 52 |
while (right > left) { |
| 53 |
/* Pivot node */ |
| 54 |
p = heap [heapIdx [right]].pos; |
| 55 |
l = left; |
| 56 |
r = right - 1; |
| 57 |
|
| 58 |
/* l & r converge, swapping elements out of order with respect to |
| 59 |
pivot node. Identical keys are resolved by cycling through |
| 60 |
dim. The convergence point is then the pivot's position. */ |
| 61 |
do { |
| 62 |
while (l <= r) { |
| 63 |
d = dim; |
| 64 |
|
| 65 |
while (heap [heapIdx [l]].pos [d] == p [d]) { |
| 66 |
d = (d + 1) % 3; |
| 67 |
|
| 68 |
if (d == dim) { |
| 69 |
/* Ignore dupes? */ |
| 70 |
error(WARNING, "duplicate keys in photon heap"); |
| 71 |
l++; |
| 72 |
break; |
| 73 |
} |
| 74 |
} |
| 75 |
|
| 76 |
if (heap [heapIdx [l]].pos [d] < p [d]) |
| 77 |
l++; |
| 78 |
else break; |
| 79 |
} |
| 80 |
|
| 81 |
while (r > l) { |
| 82 |
d = dim; |
| 83 |
|
| 84 |
while (heap [heapIdx [r]].pos [d] == p [d]) { |
| 85 |
d = (d + 1) % 3; |
| 86 |
|
| 87 |
if (d == dim) { |
| 88 |
/* Ignore dupes? */ |
| 89 |
error(WARNING, "duplicate keys in photon heap"); |
| 90 |
r--; |
| 91 |
break; |
| 92 |
} |
| 93 |
} |
| 94 |
|
| 95 |
if (heap [heapIdx [r]].pos [d] > p [d]) |
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r--; |
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else break; |
| 98 |
} |
| 99 |
|
| 100 |
/* Swap indices (not the nodes they point to) */ |
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n2 = heapIdx [l]; |
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heapIdx [l] = heapIdx [r]; |
| 103 |
heapIdx [r] = n2; |
| 104 |
/* Update reverse indices */ |
| 105 |
heapXdi [heapIdx [l]] = l; |
| 106 |
heapXdi [n2] = r; |
| 107 |
} while (l < r); |
| 108 |
|
| 109 |
/* Swap indices of convergence and pivot nodes */ |
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heapIdx [r] = heapIdx [l]; |
| 111 |
heapIdx [l] = heapIdx [right]; |
| 112 |
heapIdx [right] = n2; |
| 113 |
/* Update reverse indices */ |
| 114 |
heapXdi [heapIdx [r]] = r; |
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heapXdi [heapIdx [l]] = l; |
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heapXdi [n2] = right; |
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|
| 118 |
if (l >= m) |
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right = l - 1; |
| 120 |
if (l <= m) |
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left = l + 1; |
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} |
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|
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/* Once left & right have converged at m, we have found the median */ |
| 125 |
return m; |
| 126 |
} |
| 127 |
|
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|
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|
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static void kdT_Build (Photon *heap, unsigned long *heapIdx, |
| 131 |
unsigned long *heapXdi, const float min [3], |
| 132 |
const float max [3], unsigned long left, |
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unsigned long right, unsigned long root) |
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/* Recursive part of balancePhotons(..). Builds heap from subarray |
| 135 |
defined by indices left and right. min and max are the minimum resp. |
| 136 |
maximum photon positions in the array. root is the index of the |
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current subtree's root, which corresponds to the median's 1-based |
| 138 |
index in the heap. heapIdx are the balanced heap indices. The heap |
| 139 |
is accessed indirectly through these. heapXdi are the reverse indices |
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from the heap to heapIdx so that heapXdi [heapIdx [i]] = i. */ |
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{ |
| 142 |
float maxLeft [3], minRight [3]; |
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Photon rootNode; |
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unsigned d; |
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|
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/* Choose median for dimension with largest spread and partition |
| 147 |
accordingly */ |
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const float d0 = max [0] - min [0], |
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d1 = max [1] - min [1], |
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d2 = max [2] - min [2]; |
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const unsigned char dim = d0 > d1 ? d0 > d2 ? 0 : 2 |
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: d1 > d2 ? 1 : 2; |
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const unsigned long median = left == right |
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? left |
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: kdT_MedianPartition(heap, heapIdx, heapXdi, |
| 156 |
left, right, dim); |
| 157 |
|
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/* Place median at root of current subtree. This consists of swapping |
| 159 |
the median and the root nodes and updating the heap indices */ |
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memcpy(&rootNode, heap + heapIdx [median], sizeof(Photon)); |
| 161 |
memcpy(heap + heapIdx [median], heap + root - 1, sizeof(Photon)); |
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rootNode.discr = dim; |
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memcpy(heap + root - 1, &rootNode, sizeof(Photon)); |
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heapIdx [heapXdi [root - 1]] = heapIdx [median]; |
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heapXdi [heapIdx [median]] = heapXdi [root - 1]; |
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heapIdx [median] = root - 1; |
| 167 |
heapXdi [root - 1] = median; |
| 168 |
|
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/* Update bounds for left and right subtrees and recurse on them */ |
| 170 |
for (d = 0; d <= 2; d++) |
| 171 |
if (d == dim) |
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maxLeft [d] = minRight [d] = rootNode.pos [d]; |
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else { |
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maxLeft [d] = max [d]; |
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minRight [d] = min [d]; |
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} |
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|
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if (left < median) |
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kdT_Build(heap, heapIdx, heapXdi, min, maxLeft, left, median - 1, |
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root << 1); |
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|
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if (right > median) |
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kdT_Build(heap, heapIdx, heapXdi, minRight, max, median + 1, right, |
| 184 |
(root << 1) + 1); |
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} |
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|
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|
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|
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void kdT_BuildPhotonMap (struct PhotonMap *pmap) |
| 190 |
{ |
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Photon *nodes; |
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unsigned long i; |
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unsigned long *heapIdx, /* Photon index array */ |
| 194 |
*heapXdi; /* Reverse index to heapIdx */ |
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|
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/* Allocate kd-tree nodes and load photons from heap file */ |
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if (!(nodes = calloc(pmap -> numPhotons, sizeof(Photon)))) |
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error(SYSTEM, "failed in-core heap allocation in kdT_BuildPhotonMap"); |
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|
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rewind(pmap -> heap); |
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i = fread(nodes, sizeof(Photon), pmap -> numPhotons, pmap -> heap); |
| 202 |
if (i != |
| 203 |
pmap -> numPhotons) |
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error(SYSTEM, "failed loading photon heap in kdT_BuildPhotonMap"); |
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|
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pmap -> store.nodes = nodes; |
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heapIdx = calloc(pmap -> numPhotons, sizeof(unsigned long)); |
| 208 |
heapXdi = calloc(pmap -> numPhotons, sizeof(unsigned long)); |
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if (!heapIdx || !heapXdi) |
| 210 |
error(SYSTEM, "failed heap index allocation in kdT_BuildPhotonMap"); |
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|
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/* Initialize index arrays */ |
| 213 |
for (i = 0; i < pmap -> numPhotons; i++) |
| 214 |
heapXdi [i] = heapIdx [i] = i; |
| 215 |
|
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/* Build kd-tree */ |
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kdT_Build(nodes, heapIdx, heapXdi, pmap -> minPos, pmap -> maxPos, 0, |
| 218 |
pmap -> numPhotons - 1, 1); |
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|
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/* Cleanup */ |
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free(heapIdx); |
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free(heapXdi); |
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} |
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|
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|
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|
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int kdT_SavePhotons (const struct PhotonMap *pmap, FILE *out) |
| 228 |
{ |
| 229 |
unsigned long i, j; |
| 230 |
Photon *p = (Photon*)pmap -> store.nodes; |
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|
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for (i = 0; i < pmap -> numPhotons; i++, p++) { |
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/* Write photon attributes */ |
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for (j = 0; j < 3; j++) |
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putflt(p -> pos [j], out); |
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|
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/* Bytewise dump otherwise we have portability probs */ |
| 238 |
for (j = 0; j < 3; j++) |
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putint(p -> norm [j], 1, out); |
| 240 |
|
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#ifdef PMAP_FLOAT_FLUX |
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for (j = 0; j < 3; j++) |
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putflt(p -> flux [j], out); |
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#else |
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for (j = 0; j < 4; j++) |
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putint(p -> flux [j], 1, out); |
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#endif |
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|
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putint(p -> primary, sizeof(p -> primary), out); |
| 250 |
putint(p -> flags, 1, out); |
| 251 |
|
| 252 |
if (ferror(out)) |
| 253 |
return -1; |
| 254 |
} |
| 255 |
|
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return 0; |
| 257 |
} |
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|
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|
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|
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int kdT_LoadPhotons (struct PhotonMap *pmap, FILE *in) |
| 262 |
{ |
| 263 |
unsigned long i, j; |
| 264 |
Photon *p; |
| 265 |
|
| 266 |
/* Allocate kd-tree based on initialised pmap -> numPhotons */ |
| 267 |
pmap -> store.nodes = calloc(sizeof(Photon), pmap -> numPhotons); |
| 268 |
if (!pmap -> store.nodes) |
| 269 |
error(SYSTEM, "failed kd-tree allocation in kdT_LoadPhotons"); |
| 270 |
|
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/* Get photon attributes */ |
| 272 |
for (i = 0, p = pmap -> store.nodes; i < pmap -> numPhotons; i++, p++) { |
| 273 |
for (j = 0; j < 3; j++) |
| 274 |
p -> pos [j] = getflt(in); |
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|
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/* Bytewise grab otherwise we have portability probs */ |
| 277 |
for (j = 0; j < 3; j++) |
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p -> norm [j] = getint(1, in); |
| 279 |
|
| 280 |
#ifdef PMAP_FLOAT_FLUX |
| 281 |
for (j = 0; j < 3; j++) |
| 282 |
p -> flux [j] = getflt(in); |
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#else |
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for (j = 0; j < 4; j++) |
| 285 |
p -> flux [j] = getint(1, in); |
| 286 |
#endif |
| 287 |
|
| 288 |
p -> primary = getint(sizeof(p -> primary), in); |
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p -> flags = getint(1, in); |
| 290 |
|
| 291 |
if (feof(in)) |
| 292 |
return -1; |
| 293 |
} |
| 294 |
|
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return 0; |
| 296 |
} |
| 297 |
|
| 298 |
|
| 299 |
|
| 300 |
void kdT_InitFindPhotons (struct PhotonMap *pmap) |
| 301 |
{ |
| 302 |
pmap -> squeue.len = pmap -> maxGather + 1; |
| 303 |
pmap -> squeue.node = calloc(pmap -> squeue.len, |
| 304 |
sizeof(PhotonSearchQueueNode)); |
| 305 |
if (!pmap -> squeue.node) |
| 306 |
error(SYSTEM, "can't allocate photon search queue"); |
| 307 |
} |
| 308 |
|
| 309 |
|
| 310 |
|
| 311 |
static void kdT_FindNearest (PhotonMap *pmap, const float pos [3], |
| 312 |
const float norm [3], unsigned long node) |
| 313 |
/* Recursive part of kdT_FindPhotons(). Locate pmap -> squeue.len nearest |
| 314 |
* neighbours to pos with similar normal and return in search queue starting |
| 315 |
* at pmap -> squeue.node. Note that all heap and queue indices are |
| 316 |
* 1-based, but accesses to the arrays are 0-based! */ |
| 317 |
{ |
| 318 |
Photon *p = (Photon*)pmap -> store.nodes + node - 1; |
| 319 |
unsigned i, j; |
| 320 |
/* Signed distance to current photon's splitting plane */ |
| 321 |
float d = pos [p -> discr] - p -> pos [p -> discr], |
| 322 |
d2 = d * d, dv [3]; |
| 323 |
PhotonSearchQueueNode* sq = pmap -> squeue.node; |
| 324 |
const unsigned sqSize = pmap -> squeue.len; |
| 325 |
|
| 326 |
/* Search subtree closer to pos first; exclude other subtree if the |
| 327 |
distance to the splitting plane is greater than maxDist */ |
| 328 |
if (d < 0) { |
| 329 |
if (node << 1 <= pmap -> numPhotons) |
| 330 |
kdT_FindNearest(pmap, pos, norm, node << 1); |
| 331 |
|
| 332 |
if (d2 < pmap -> maxDist2 && node << 1 < pmap -> numPhotons) |
| 333 |
kdT_FindNearest(pmap, pos, norm, (node << 1) + 1); |
| 334 |
} |
| 335 |
else { |
| 336 |
if (node << 1 < pmap -> numPhotons) |
| 337 |
kdT_FindNearest(pmap, pos, norm, (node << 1) + 1); |
| 338 |
|
| 339 |
if (d2 < pmap -> maxDist2 && node << 1 <= pmap -> numPhotons) |
| 340 |
kdT_FindNearest(pmap, pos, norm, node << 1); |
| 341 |
} |
| 342 |
|
| 343 |
/* Reject photon if normal faces away (ignored for volume photons) with |
| 344 |
* tolerance to account for perturbation; note photon normal is coded |
| 345 |
* in range [-127,127], hence we factor this in */ |
| 346 |
if (norm && DOT(norm, p -> norm) <= PMAP_NORM_TOL * 127 * frandom()) |
| 347 |
return; |
| 348 |
|
| 349 |
if (isContribPmap(pmap)) { |
| 350 |
/* Lookup in contribution photon map; filter according to emitting |
| 351 |
* light source if contrib list set, else accept all */ |
| 352 |
|
| 353 |
if (pmap -> srcContrib) { |
| 354 |
OBJREC *srcMod; |
| 355 |
const int srcIdx = photonSrcIdx(pmap, p); |
| 356 |
|
| 357 |
if (srcIdx < 0 || srcIdx >= nsources) |
| 358 |
error(INTERNAL, "invalid light source index in photon map"); |
| 359 |
|
| 360 |
srcMod = findmaterial(source [srcIdx].so); |
| 361 |
|
| 362 |
/* Reject photon if contributions from light source which emitted it |
| 363 |
* are not sought */ |
| 364 |
if (!lu_find(pmap -> srcContrib, srcMod -> oname) -> data) |
| 365 |
return; |
| 366 |
} |
| 367 |
|
| 368 |
/* Reject non-caustic photon if lookup for caustic contribs */ |
| 369 |
if (pmap -> lookupCaustic & !p -> caustic) |
| 370 |
return; |
| 371 |
} |
| 372 |
|
| 373 |
/* Squared distance to current photon (note dist2() requires doubles) */ |
| 374 |
VSUB(dv, pos, p -> pos); |
| 375 |
d2 = DOT(dv, dv); |
| 376 |
|
| 377 |
/* Accept photon if closer than current max dist & add to priority queue */ |
| 378 |
if (d2 < pmap -> maxDist2) { |
| 379 |
if (pmap -> squeue.tail < sqSize) { |
| 380 |
/* Priority queue not full; append photon and restore heap */ |
| 381 |
i = ++pmap -> squeue.tail; |
| 382 |
|
| 383 |
while (i > 1 && sq [(i >> 1) - 1].dist2 <= d2) { |
| 384 |
sq [i - 1].idx = sq [(i >> 1) - 1].idx; |
| 385 |
sq [i - 1].dist2 = sq [(i >> 1) - 1].dist2; |
| 386 |
i >>= 1; |
| 387 |
} |
| 388 |
|
| 389 |
sq [--i].idx = (PhotonIdx)p; |
| 390 |
sq [i].dist2 = d2; |
| 391 |
/* Update maxDist if we've just filled the queue */ |
| 392 |
if (pmap -> squeue.tail >= pmap -> squeue.len) |
| 393 |
pmap -> maxDist2 = sq [0].dist2; |
| 394 |
} |
| 395 |
else { |
| 396 |
/* Priority queue full; replace maximum, restore heap, and |
| 397 |
update maxDist */ |
| 398 |
i = 1; |
| 399 |
|
| 400 |
while (i <= sqSize >> 1) { |
| 401 |
j = i << 1; |
| 402 |
if (j < sqSize && sq [j - 1].dist2 < sq [j].dist2) |
| 403 |
j++; |
| 404 |
if (d2 >= sq [j - 1].dist2) |
| 405 |
break; |
| 406 |
sq [i - 1].idx = sq [j - 1].idx; |
| 407 |
sq [i - 1].dist2 = sq [j - 1].dist2; |
| 408 |
i = j; |
| 409 |
} |
| 410 |
|
| 411 |
sq [--i].idx = (PhotonIdx)p; |
| 412 |
sq [i].dist2 = d2; |
| 413 |
pmap -> maxDist2 = sq [0].dist2; |
| 414 |
} |
| 415 |
} |
| 416 |
} |
| 417 |
|
| 418 |
|
| 419 |
|
| 420 |
void kdT_FindPhotons (struct PhotonMap *pmap, const FVECT pos, |
| 421 |
const FVECT norm) |
| 422 |
{ |
| 423 |
float p [3], n [3]; |
| 424 |
|
| 425 |
/* Photon pos & normal stored at lower precision */ |
| 426 |
VCOPY(p, pos); |
| 427 |
VCOPY(n, norm); |
| 428 |
kdT_FindNearest(pmap, p, n, 1); |
| 429 |
} |
| 430 |
|
| 431 |
|
| 432 |
|
| 433 |
static void kdT_Find1Nearest (PhotonMap *pmap, const float pos [3], |
| 434 |
const float norm [3], Photon **photon, |
| 435 |
unsigned long node) |
| 436 |
/* Recursive part of kdT_Find1Photon(). Locate single nearest neighbour to |
| 437 |
* pos with similar normal. Note that all heap and queue indices are |
| 438 |
* 1-based, but accesses to the arrays are 0-based! */ |
| 439 |
{ |
| 440 |
Photon *p = (Photon*)pmap -> store.nodes + node - 1; |
| 441 |
/* Signed distance to current photon's splitting plane */ |
| 442 |
float d = pos [p -> discr] - p -> pos [p -> discr], d2 = d * d, |
| 443 |
dv [3]; |
| 444 |
|
| 445 |
/* Search subtree closer to pos first; exclude other subtree if the |
| 446 |
distance to the splitting plane is greater than maxDist */ |
| 447 |
if (d < 0) { |
| 448 |
if (node << 1 <= pmap -> numPhotons) |
| 449 |
kdT_Find1Nearest(pmap, pos, norm, photon, node << 1); |
| 450 |
|
| 451 |
if (d2 < pmap -> maxDist2 && node << 1 < pmap -> numPhotons) |
| 452 |
kdT_Find1Nearest(pmap, pos, norm, photon, (node << 1) + 1); |
| 453 |
} |
| 454 |
else { |
| 455 |
if (node << 1 < pmap -> numPhotons) |
| 456 |
kdT_Find1Nearest(pmap, pos, norm, photon, (node << 1) + 1); |
| 457 |
|
| 458 |
if (d2 < pmap -> maxDist2 && node << 1 <= pmap -> numPhotons) |
| 459 |
kdT_Find1Nearest(pmap, pos, norm, photon, node << 1); |
| 460 |
} |
| 461 |
|
| 462 |
/* Squared distance to current photon */ |
| 463 |
VSUB(dv, pos, p -> pos); |
| 464 |
d2 = DOT(dv, dv); |
| 465 |
|
| 466 |
if (d2 < pmap -> maxDist2 && |
| 467 |
DOT(norm, p -> norm) > PMAP_NORM_TOL * 127 * frandom()) { |
| 468 |
/* Closest photon so far with similar normal. We allow for tolerance |
| 469 |
* to account for perturbation in the latter; note the photon normal |
| 470 |
* is coded in the range [-127,127], hence we factor this in */ |
| 471 |
pmap -> maxDist2 = d2; |
| 472 |
*photon = p; |
| 473 |
} |
| 474 |
} |
| 475 |
|
| 476 |
|
| 477 |
|
| 478 |
void kdT_Find1Photon (struct PhotonMap *pmap, const FVECT pos, |
| 479 |
const FVECT norm, Photon *photon) |
| 480 |
{ |
| 481 |
float p [3], n [3]; |
| 482 |
Photon *pnn; |
| 483 |
|
| 484 |
/* Photon pos & normal stored at lower precision */ |
| 485 |
VCOPY(p, pos); |
| 486 |
VCOPY(n, norm); |
| 487 |
kdT_Find1Nearest(pmap, p, n, &pnn, 1); |
| 488 |
memcpy(photon, pnn, sizeof(Photon)); |
| 489 |
} |
| 490 |
|
| 491 |
|
| 492 |
|
| 493 |
int kdT_GetPhoton (const struct PhotonMap *pmap, PhotonIdx idx, |
| 494 |
Photon *photon) |
| 495 |
{ |
| 496 |
memcpy(photon, idx, sizeof(Photon)); |
| 497 |
return 0; |
| 498 |
} |
| 499 |
|
| 500 |
|
| 501 |
|
| 502 |
Photon *kdT_GetNearestPhoton (const PhotonSearchQueue *squeue, PhotonIdx idx) |
| 503 |
{ |
| 504 |
return idx; |
| 505 |
} |
| 506 |
|
| 507 |
|
| 508 |
|
| 509 |
PhotonIdx kdT_FirstPhoton (const struct PhotonMap* pmap) |
| 510 |
{ |
| 511 |
return pmap -> store.nodes; |
| 512 |
} |
| 513 |
|
| 514 |
|
| 515 |
|
| 516 |
void kdT_Delete (PhotonKdTree *kdt) |
| 517 |
{ |
| 518 |
free(kdt -> nodes); |
| 519 |
kdt -> nodes = NULL; |
| 520 |
} |
