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rschregle |
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/* |
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================================================================== |
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In-core kd-tree for photon map |
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Roland Schregle (roland.schregle@{hslu.ch, gmail.com}) |
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(c) Fraunhofer Institute for Solar Energy Systems, |
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(c) Lucerne University of Applied Sciences and Arts, |
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supported by the Swiss National Science Foundation (SNSF, #147053) |
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================================================================== |
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$Id: pmapkdt.c,v 1.5 2016/02/04 20:23:27 taschreg Exp taschreg $ |
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*/ |
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#ifdef PMAP_OOC |
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/* Checked in pmapdata.h */ |
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#undef PMAP_OOC |
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#endif |
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#include "pmapdata.h" /* Includes pmapkdt.h */ |
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#include "source.h" |
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void kdT_Null (PhotonKdTree *kdt) |
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{ |
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kdt -> nodes = NULL; |
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} |
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static unsigned long kdT_MedianPartition (const Photon *heap, |
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unsigned long *heapIdx, |
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unsigned long *heapXdi, |
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unsigned long left, |
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unsigned long right, unsigned dim) |
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/* Returns index to median in heap from indices left to right |
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(inclusive) in dimension dim. The heap is partitioned relative to |
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median using a quicksort algorithm. The heap indices in heapIdx are |
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sorted rather than the heap itself. */ |
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{ |
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const float *p; |
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unsigned long l, r, lg2, n2, m, n = right - left + 1; |
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unsigned d; |
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/* Round down n to nearest power of 2 */ |
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for (lg2 = 0, n2 = n; n2 > 1; n2 >>= 1, ++lg2); |
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n2 = 1 << lg2; |
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/* Determine median position; this takes into account the fact that |
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only the last level in the heap can be partially empty, and that |
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it fills from left to right */ |
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m = left + ((n - n2) > (n2 >> 1) - 1 ? n2 - 1 : n - (n2 >> 1)); |
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while (right > left) { |
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/* Pivot node */ |
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p = heap [heapIdx [right]].pos; |
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l = left; |
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r = right - 1; |
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/* l & r converge, swapping elements out of order with respect to |
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pivot node. Identical keys are resolved by cycling through |
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dim. The convergence point is then the pivot's position. */ |
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do { |
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while (l <= r) { |
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d = dim; |
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while (heap [heapIdx [l]].pos [d] == p [d]) { |
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d = (d + 1) % 3; |
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if (d == dim) { |
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/* Ignore dupes? */ |
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error(WARNING, "duplicate keys in photon heap"); |
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l++; |
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break; |
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} |
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} |
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if (heap [heapIdx [l]].pos [d] < p [d]) |
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l++; |
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else break; |
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} |
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while (r > l) { |
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d = dim; |
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while (heap [heapIdx [r]].pos [d] == p [d]) { |
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d = (d + 1) % 3; |
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if (d == dim) { |
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/* Ignore dupes? */ |
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error(WARNING, "duplicate keys in photon heap"); |
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r--; |
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break; |
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} |
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} |
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if (heap [heapIdx [r]].pos [d] > p [d]) |
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r--; |
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else break; |
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} |
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/* Swap indices (not the nodes they point to) */ |
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n2 = heapIdx [l]; |
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heapIdx [l] = heapIdx [r]; |
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heapIdx [r] = n2; |
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/* Update reverse indices */ |
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heapXdi [heapIdx [l]] = l; |
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heapXdi [n2] = r; |
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} while (l < r); |
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/* Swap indices of convergence and pivot nodes */ |
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heapIdx [r] = heapIdx [l]; |
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heapIdx [l] = heapIdx [right]; |
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heapIdx [right] = n2; |
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/* Update reverse indices */ |
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heapXdi [heapIdx [r]] = r; |
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heapXdi [heapIdx [l]] = l; |
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heapXdi [n2] = right; |
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if (l >= m) |
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right = l - 1; |
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if (l <= m) |
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left = l + 1; |
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} |
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/* Once left & right have converged at m, we have found the median */ |
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return m; |
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} |
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static void kdT_Build (Photon *heap, unsigned long *heapIdx, |
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unsigned long *heapXdi, const float min [3], |
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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 |
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defined by indices left and right. min and max are the minimum resp. |
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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 |
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index in the heap. heapIdx are the balanced heap indices. The heap |
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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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{ |
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float maxLeft [3], minRight [3]; |
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Photon rootNode; |
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unsigned d; |
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/* Choose median for dimension with largest spread and partition |
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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, |
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left, right, dim); |
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/* Place median at root of current subtree. This consists of swapping |
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the median and the root nodes and updating the heap indices */ |
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memcpy(&rootNode, heap + heapIdx [median], sizeof(Photon)); |
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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; |
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heapXdi [root - 1] = median; |
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/* Update bounds for left and right subtrees and recurse on them */ |
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for (d = 0; d <= 2; d++) |
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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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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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if (right > median) |
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kdT_Build(heap, heapIdx, heapXdi, minRight, max, median + 1, right, |
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(root << 1) + 1); |
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} |
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void kdT_BuildPhotonMap (struct PhotonMap *pmap) |
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{ |
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Photon *nodes; |
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unsigned long i; |
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unsigned long *heapIdx, /* Photon index array */ |
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*heapXdi; /* Reverse index to heapIdx */ |
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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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rewind(pmap -> heap); |
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if (fread(nodes, sizeof(Photon), pmap -> numPhotons, pmap -> heap) != |
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pmap -> numPhotons) |
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error(SYSTEM, "failed loading photon heap in kdT_BuildPhotonMap"); |
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pmap -> store.nodes = nodes; |
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heapIdx = calloc(pmap -> numPhotons, sizeof(unsigned long)); |
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heapXdi = calloc(pmap -> numPhotons, sizeof(unsigned long)); |
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if (!heapIdx || !heapXdi) |
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error(SYSTEM, "failed heap index allocation in kdT_BuildPhotonMap"); |
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/* Initialize index arrays */ |
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for (i = 0; i < pmap -> numPhotons; i++) |
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heapXdi [i] = heapIdx [i] = i; |
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/* Build kd-tree */ |
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kdT_Build(nodes, heapIdx, heapXdi, pmap -> minPos, pmap -> maxPos, 0, |
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pmap -> numPhotons - 1, 1); |
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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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int kdT_SavePhotons (const struct PhotonMap *pmap, FILE *out) |
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{ |
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unsigned long i, j; |
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Photon *p = (Photon*)pmap -> store.nodes; |
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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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/* Bytewise dump otherwise we have portability probs */ |
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for (j = 0; j < 3; j++) |
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putint(p -> norm [j], 1, out); |
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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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putint(p -> primary, sizeof(p -> primary), out); |
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putint(p -> flags, 1, out); |
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if (ferror(out)) |
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return -1; |
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} |
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return 0; |
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} |
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int kdT_LoadPhotons (struct PhotonMap *pmap, FILE *in) |
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{ |
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unsigned long i, j; |
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Photon *p; |
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/* Allocate kd-tree based on initialised pmap -> numPhotons */ |
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pmap -> store.nodes = calloc(sizeof(Photon), pmap -> numPhotons); |
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if (!pmap -> store.nodes) |
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error(SYSTEM, "failed kd-tree allocation in kdT_LoadPhotons"); |
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/* Get photon attributes */ |
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for (i = 0, p = pmap -> store.nodes; i < pmap -> numPhotons; i++, p++) { |
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for (j = 0; j < 3; j++) |
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p -> pos [j] = getflt(in); |
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/* Bytewise grab otherwise we have portability probs */ |
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for (j = 0; j < 3; j++) |
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p -> norm [j] = getint(1, in); |
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#ifdef PMAP_FLOAT_FLUX |
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for (j = 0; j < 3; j++) |
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p -> flux [j] = getflt(in); |
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#else |
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for (j = 0; j < 4; j++) |
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p -> flux [j] = getint(1, in); |
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#endif |
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p -> primary = getint(sizeof(p -> primary), in); |
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p -> flags = getint(1, in); |
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if (feof(in)) |
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return -1; |
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} |
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return 0; |
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} |
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void kdT_InitFindPhotons (struct PhotonMap *pmap) |
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{ |
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pmap -> squeue.len = pmap -> maxGather + 1; |
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pmap -> squeue.node = calloc(pmap -> squeue.len, |
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sizeof(PhotonSearchQueueNode)); |
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if (!pmap -> squeue.node) |
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error(SYSTEM, "can't allocate photon search queue"); |
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} |
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static void kdT_FindNearest (PhotonMap *pmap, const float pos [3], |
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const float norm [3], unsigned long node) |
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/* Recursive part of kdT_FindPhotons(). Locate pmap -> squeue.len nearest |
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* neighbours to pos with similar normal and return in search queue starting |
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* at pmap -> squeue.node. Note that all heap and queue indices are |
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* 1-based, but accesses to the arrays are 0-based! */ |
| 319 |
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{ |
| 320 |
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Photon *p = (Photon*)pmap -> store.nodes + node - 1; |
| 321 |
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unsigned i, j; |
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/* Signed distance to current photon's splitting plane */ |
| 323 |
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float d = pos [p -> discr] - p -> pos [p -> discr], |
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d2 = d * d, dv [3]; |
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PhotonSearchQueueNode* sq = pmap -> squeue.node; |
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const unsigned sqSize = pmap -> squeue.len; |
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| 328 |
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/* Search subtree closer to pos first; exclude other subtree if the |
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distance to the splitting plane is greater than maxDist */ |
| 330 |
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if (d < 0) { |
| 331 |
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if (node << 1 <= pmap -> numPhotons) |
| 332 |
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kdT_FindNearest(pmap, pos, norm, node << 1); |
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| 334 |
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if (d2 < pmap -> maxDist2 && node << 1 < pmap -> numPhotons) |
| 335 |
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kdT_FindNearest(pmap, pos, norm, (node << 1) + 1); |
| 336 |
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} |
| 337 |
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else { |
| 338 |
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if (node << 1 < pmap -> numPhotons) |
| 339 |
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kdT_FindNearest(pmap, pos, norm, (node << 1) + 1); |
| 340 |
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| 341 |
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if (d2 < pmap -> maxDist2 && node << 1 <= pmap -> numPhotons) |
| 342 |
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kdT_FindNearest(pmap, pos, norm, node << 1); |
| 343 |
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} |
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| 345 |
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/* Reject photon if normal faces away (ignored for volume photons) with |
| 346 |
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* tolerance to account for perturbation; note photon normal is coded |
| 347 |
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* in range [-127,127], hence we factor this in */ |
| 348 |
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if (norm && DOT(norm, p -> norm) <= PMAP_NORM_TOL * 127 * frandom()) |
| 349 |
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return; |
| 350 |
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| 351 |
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if (isContribPmap(pmap) && pmap -> srcContrib) { |
| 352 |
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/* Lookup in contribution photon map */ |
| 353 |
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OBJREC *srcMod; |
| 354 |
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const int srcIdx = photonSrcIdx(pmap, p); |
| 355 |
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| 356 |
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if (srcIdx < 0 || srcIdx >= nsources) |
| 357 |
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error(INTERNAL, "invalid light source index in photon map"); |
| 358 |
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srcMod = findmaterial(source [srcIdx].so); |
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/* Reject photon if contributions from light source which emitted it |
| 362 |
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* are not sought */ |
| 363 |
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if (!lu_find(pmap -> srcContrib, srcMod -> oname) -> data) |
| 364 |
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return; |
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|
|
/* Reject non-caustic photon if lookup for caustic contribs */ |
| 367 |
|
|
if (pmap -> lookupCaustic & !p -> caustic) |
| 368 |
|
|
return; |
| 369 |
|
|
} |
| 370 |
|
|
|
| 371 |
|
|
/* Squared distance to current photon (note dist2() requires doubles) */ |
| 372 |
|
|
VSUB(dv, pos, p -> pos); |
| 373 |
|
|
d2 = DOT(dv, dv); |
| 374 |
|
|
|
| 375 |
|
|
/* Accept photon if closer than current max dist & add to priority queue */ |
| 376 |
|
|
if (d2 < pmap -> maxDist2) { |
| 377 |
|
|
if (pmap -> squeue.tail < sqSize) { |
| 378 |
|
|
/* Priority queue not full; append photon and restore heap */ |
| 379 |
|
|
i = ++pmap -> squeue.tail; |
| 380 |
|
|
|
| 381 |
|
|
while (i > 1 && sq [(i >> 1) - 1].dist2 <= d2) { |
| 382 |
|
|
sq [i - 1].idx = sq [(i >> 1) - 1].idx; |
| 383 |
|
|
sq [i - 1].dist2 = sq [(i >> 1) - 1].dist2; |
| 384 |
|
|
i >>= 1; |
| 385 |
|
|
} |
| 386 |
|
|
|
| 387 |
|
|
sq [--i].idx = (PhotonIdx)p; |
| 388 |
|
|
sq [i].dist2 = d2; |
| 389 |
|
|
/* Update maxDist if we've just filled the queue */ |
| 390 |
|
|
if (pmap -> squeue.tail >= pmap -> squeue.len) |
| 391 |
|
|
pmap -> maxDist2 = sq [0].dist2; |
| 392 |
|
|
} |
| 393 |
|
|
else { |
| 394 |
|
|
/* Priority queue full; replace maximum, restore heap, and |
| 395 |
|
|
update maxDist */ |
| 396 |
|
|
i = 1; |
| 397 |
|
|
|
| 398 |
|
|
while (i <= sqSize >> 1) { |
| 399 |
|
|
j = i << 1; |
| 400 |
|
|
if (j < sqSize && sq [j - 1].dist2 < sq [j].dist2) |
| 401 |
|
|
j++; |
| 402 |
|
|
if (d2 >= sq [j - 1].dist2) |
| 403 |
|
|
break; |
| 404 |
|
|
sq [i - 1].idx = sq [j - 1].idx; |
| 405 |
|
|
sq [i - 1].dist2 = sq [j - 1].dist2; |
| 406 |
|
|
i = j; |
| 407 |
|
|
} |
| 408 |
|
|
|
| 409 |
|
|
sq [--i].idx = (PhotonIdx)p; |
| 410 |
|
|
sq [i].dist2 = d2; |
| 411 |
|
|
pmap -> maxDist2 = sq [0].dist2; |
| 412 |
|
|
} |
| 413 |
|
|
} |
| 414 |
|
|
} |
| 415 |
|
|
|
| 416 |
|
|
|
| 417 |
|
|
|
| 418 |
|
|
void kdT_FindPhotons (struct PhotonMap *pmap, const FVECT pos, |
| 419 |
|
|
const FVECT norm) |
| 420 |
|
|
{ |
| 421 |
|
|
float p [3], n [3]; |
| 422 |
|
|
|
| 423 |
|
|
/* Photon pos & normal stored at lower precision */ |
| 424 |
|
|
VCOPY(p, pos); |
| 425 |
|
|
VCOPY(n, norm); |
| 426 |
|
|
kdT_FindNearest(pmap, p, n, 1); |
| 427 |
|
|
} |
| 428 |
|
|
|
| 429 |
|
|
|
| 430 |
|
|
|
| 431 |
|
|
static void kdT_Find1Nearest (PhotonMap *pmap, const float pos [3], |
| 432 |
|
|
const float norm [3], Photon **photon, |
| 433 |
|
|
unsigned long node) |
| 434 |
|
|
/* Recursive part of kdT_Find1Photon(). Locate single nearest neighbour to |
| 435 |
|
|
* pos with similar normal. Note that all heap and queue indices are |
| 436 |
|
|
* 1-based, but accesses to the arrays are 0-based! */ |
| 437 |
|
|
{ |
| 438 |
|
|
Photon *p = (Photon*)pmap -> store.nodes + node - 1; |
| 439 |
|
|
/* Signed distance to current photon's splitting plane */ |
| 440 |
|
|
float d = pos [p -> discr] - p -> pos [p -> discr], d2 = d * d, |
| 441 |
|
|
dv [3]; |
| 442 |
|
|
|
| 443 |
|
|
/* Search subtree closer to pos first; exclude other subtree if the |
| 444 |
|
|
distance to the splitting plane is greater than maxDist */ |
| 445 |
|
|
if (d < 0) { |
| 446 |
|
|
if (node << 1 <= pmap -> numPhotons) |
| 447 |
|
|
kdT_Find1Nearest(pmap, pos, norm, photon, node << 1); |
| 448 |
|
|
|
| 449 |
|
|
if (d2 < pmap -> maxDist2 && node << 1 < pmap -> numPhotons) |
| 450 |
|
|
kdT_Find1Nearest(pmap, pos, norm, photon, (node << 1) + 1); |
| 451 |
|
|
} |
| 452 |
|
|
else { |
| 453 |
|
|
if (node << 1 < pmap -> numPhotons) |
| 454 |
|
|
kdT_Find1Nearest(pmap, pos, norm, photon, (node << 1) + 1); |
| 455 |
|
|
|
| 456 |
|
|
if (d2 < pmap -> maxDist2 && node << 1 <= pmap -> numPhotons) |
| 457 |
|
|
kdT_Find1Nearest(pmap, pos, norm, photon, node << 1); |
| 458 |
|
|
} |
| 459 |
|
|
|
| 460 |
|
|
/* Squared distance to current photon */ |
| 461 |
|
|
VSUB(dv, pos, p -> pos); |
| 462 |
|
|
d2 = DOT(dv, dv); |
| 463 |
|
|
|
| 464 |
|
|
if (d2 < pmap -> maxDist2 && |
| 465 |
|
|
DOT(norm, p -> norm) > PMAP_NORM_TOL * 127 * frandom()) { |
| 466 |
|
|
/* Closest photon so far with similar normal. We allow for tolerance |
| 467 |
|
|
* to account for perturbation in the latter; note the photon normal |
| 468 |
|
|
* is coded in the range [-127,127], hence we factor this in */ |
| 469 |
|
|
pmap -> maxDist2 = d2; |
| 470 |
|
|
*photon = p; |
| 471 |
|
|
} |
| 472 |
|
|
} |
| 473 |
|
|
|
| 474 |
|
|
|
| 475 |
|
|
|
| 476 |
|
|
void kdT_Find1Photon (struct PhotonMap *pmap, const FVECT pos, |
| 477 |
|
|
const FVECT norm, Photon *photon) |
| 478 |
|
|
{ |
| 479 |
|
|
float p [3], n [3]; |
| 480 |
|
|
Photon *pnn; |
| 481 |
|
|
|
| 482 |
|
|
/* Photon pos & normal stored at lower precision */ |
| 483 |
|
|
VCOPY(p, pos); |
| 484 |
|
|
VCOPY(n, norm); |
| 485 |
|
|
kdT_Find1Nearest(pmap, p, n, &pnn, 1); |
| 486 |
|
|
memcpy(photon, pnn, sizeof(Photon)); |
| 487 |
|
|
} |
| 488 |
|
|
|
| 489 |
|
|
|
| 490 |
|
|
|
| 491 |
|
|
int kdT_GetPhoton (const struct PhotonMap *pmap, PhotonIdx idx, |
| 492 |
|
|
Photon *photon) |
| 493 |
|
|
{ |
| 494 |
|
|
memcpy(photon, idx, sizeof(Photon)); |
| 495 |
|
|
return 0; |
| 496 |
|
|
} |
| 497 |
|
|
|
| 498 |
|
|
|
| 499 |
|
|
|
| 500 |
|
|
Photon *kdT_GetNearestPhoton (const PhotonSearchQueue *squeue, PhotonIdx idx) |
| 501 |
|
|
{ |
| 502 |
|
|
return idx; |
| 503 |
|
|
} |
| 504 |
|
|
|
| 505 |
|
|
|
| 506 |
|
|
|
| 507 |
|
|
PhotonIdx kdT_FirstPhoton (const struct PhotonMap* pmap) |
| 508 |
|
|
{ |
| 509 |
|
|
return pmap -> store.nodes; |
| 510 |
|
|
} |
| 511 |
|
|
|
| 512 |
|
|
|
| 513 |
|
|
|
| 514 |
|
|
void kdT_Delete (PhotonKdTree *kdt) |
| 515 |
|
|
{ |
| 516 |
|
|
free(kdt -> nodes); |
| 517 |
|
|
kdt -> nodes = NULL; |
| 518 |
|
|
} |
