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/*************************************************************************
* Copyright (C) 2010-2014 Tavian Barnes <tavianator@tavianator.com> *
* *
* This file is part of The Dimension Library. *
* *
* The Dimension Library is free software; you can redistribute it and/ *
* or modify it under the terms of the GNU Lesser General Public License *
* as published by the Free Software Foundation; either version 3 of the *
* License, or (at your option) any later version. *
* *
* The Dimension Library is distributed in the hope that it will be *
* useful, but WITHOUT ANY WARRANTY; without even the implied warranty *
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
* Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public *
* License along with this program. If not, see *
* <http://www.gnu.org/licenses/>. *
*************************************************************************/
/**
* @file
* Priority R-tree implementation.
*/
#include "dimension-internal.h"
#include <stdlib.h>
/** Number of children per PR-node. */
#define DMNSN_PRTREE_B 8
/** Number of priority leaves per pseudo-PR-node (must be 2*ndimensions). */
#define DMNSN_PSEUDO_B 6
/** The side of the split that a node ended up on. */
typedef enum dmnsn_prnode_location {
DMNSN_PRTREE_LEAF, /**< Priority leaf. */
DMNSN_PRTREE_LEFT, /**< Left child. */
DMNSN_PRTREE_RIGHT /**< Right child. */
} dmnsn_prnode_location;
/** Construct an empty PR-node. */
static inline dmnsn_bvh_node *
dmnsn_new_prnode(void)
{
dmnsn_bvh_node *node = dmnsn_new_bvh_node(DMNSN_PRTREE_B);
node->data = DMNSN_PRTREE_LEFT; /* Mustn't be _LEAF */
return node;
}
/** Comparator types. */
enum {
DMNSN_XMIN,
DMNSN_YMIN,
DMNSN_ZMIN,
DMNSN_XMAX,
DMNSN_YMAX,
DMNSN_ZMAX
};
/* List sorting comparators */
static int
dmnsn_xmin_comp(const void *l, const void *r)
{
double lval = (*(const dmnsn_bvh_node **)l)->bounding_box.min.x;
double rval = (*(const dmnsn_bvh_node **)r)->bounding_box.min.x;
return (lval > rval) - (lval < rval);
}
static int
dmnsn_ymin_comp(const void *l, const void *r)
{
double lval = (*(const dmnsn_bvh_node **)l)->bounding_box.min.y;
double rval = (*(const dmnsn_bvh_node **)r)->bounding_box.min.y;
return (lval > rval) - (lval < rval);
}
static int
dmnsn_zmin_comp(const void *l, const void *r)
{
double lval = (*(const dmnsn_bvh_node **)l)->bounding_box.min.z;
double rval = (*(const dmnsn_bvh_node **)r)->bounding_box.min.z;
return (lval > rval) - (lval < rval);
}
static int
dmnsn_xmax_comp(const void *l, const void *r)
{
double lval = (*(const dmnsn_bvh_node **)l)->bounding_box.max.x;
double rval = (*(const dmnsn_bvh_node **)r)->bounding_box.max.x;
return (lval < rval) - (lval > rval);
}
static int
dmnsn_ymax_comp(const void *l, const void *r)
{
double lval = (*(const dmnsn_bvh_node **)l)->bounding_box.max.y;
double rval = (*(const dmnsn_bvh_node **)r)->bounding_box.max.y;
return (lval < rval) - (lval > rval);
}
static int
dmnsn_zmax_comp(const void *l, const void *r)
{
double lval = (*(const dmnsn_bvh_node **)l)->bounding_box.max.z;
double rval = (*(const dmnsn_bvh_node **)r)->bounding_box.max.z;
return (lval < rval) - (lval > rval);
}
/** All comparators. */
static dmnsn_array_comparator_fn *const dmnsn_comparators[DMNSN_PSEUDO_B] = {
[DMNSN_XMIN] = dmnsn_xmin_comp,
[DMNSN_YMIN] = dmnsn_ymin_comp,
[DMNSN_ZMIN] = dmnsn_zmin_comp,
[DMNSN_XMAX] = dmnsn_xmax_comp,
[DMNSN_YMAX] = dmnsn_ymax_comp,
[DMNSN_ZMAX] = dmnsn_zmax_comp,
};
/** Add the priority leaves for this level. */
static void
dmnsn_add_priority_leaves(dmnsn_bvh_node **sorted_leaves[DMNSN_PSEUDO_B],
size_t nleaves,
dmnsn_array *new_leaves)
{
for (size_t i = 0; i < DMNSN_PSEUDO_B; ++i) {
dmnsn_bvh_node *leaf = NULL;
dmnsn_bvh_node **leaves = sorted_leaves[i];
for (size_t j = 0;
j < nleaves && (!leaf || leaf->nchildren < DMNSN_PRTREE_B);
++j)
{
/* Skip all the previously found extreme nodes */
if (leaves[j]->data == DMNSN_PRTREE_LEAF) {
continue;
}
if (!leaf) {
leaf = dmnsn_new_prnode();
}
leaves[j]->data = DMNSN_PRTREE_LEAF;
dmnsn_bvh_node_add(leaf, leaves[j]);
}
if (leaf) {
dmnsn_array_push(new_leaves, &leaf);
} else {
return;
}
}
}
static void
dmnsn_split_sorted_leaves_easy(dmnsn_bvh_node **leaves,
size_t *nleaves,
size_t *nright_leaves)
{
/* Get rid of the extreme nodes */
size_t i, skip, size = *nleaves;
for (i = 0, skip = 0; i < size; ++i) {
if (leaves[i]->data == DMNSN_PRTREE_LEAF) {
++skip;
} else {
leaves[i - skip] = leaves[i];
}
}
size -= skip;
/* Split the leaves and mark the left and right child nodes */
size_t left_size = (size + 1)/2;
for (i = 0; i < left_size; ++i) {
leaves[i]->data = DMNSN_PRTREE_LEFT;
}
for (i = left_size; i < size; ++i) {
leaves[i]->data = DMNSN_PRTREE_RIGHT;
}
*nleaves = left_size;
*nright_leaves = size - left_size;
}
static void
dmnsn_split_sorted_leaves_hard(dmnsn_bvh_node **leaves,
dmnsn_bvh_node **buffer,
size_t nleaves)
{
size_t i, j, skip;
for (i = 0, j = 0, skip = 0; i < nleaves; ++i) {
if (leaves[i]->data == DMNSN_PRTREE_LEFT) {
leaves[i - skip] = leaves[i];
} else {
if (leaves[i]->data == DMNSN_PRTREE_RIGHT) {
buffer[j] = leaves[i];
++j;
}
++skip;
}
}
size_t left_size = i - skip;
for (i = 0; i < j; ++i) {
leaves[left_size + i] = buffer[i];
}
}
/** Split the sorted lists into the left and right subtrees. */
static void
dmnsn_split_sorted_leaves(dmnsn_bvh_node **sorted_leaves[DMNSN_PSEUDO_B],
size_t *nleaves,
dmnsn_bvh_node **right_sorted_leaves[DMNSN_PSEUDO_B],
size_t *nright_leaves,
dmnsn_bvh_node **buffer,
size_t i)
{
size_t original_size = *nleaves;
/* Split the ith list */
dmnsn_split_sorted_leaves_easy(sorted_leaves[i], nleaves, nright_leaves);
/* Split the rest of the lists */
for (size_t j = 0; j < DMNSN_PSEUDO_B; ++j) {
right_sorted_leaves[j] = sorted_leaves[j] + *nleaves;
if (j == i) {
continue;
}
dmnsn_split_sorted_leaves_hard(sorted_leaves[j], buffer, original_size);
}
}
/** Recursively constructs an implicit pseudo-PR-tree and collects the priority
leaves. */
static void
dmnsn_priority_leaves_recursive(dmnsn_bvh_node **sorted_leaves[DMNSN_PSEUDO_B],
size_t nleaves,
dmnsn_bvh_node **buffer,
dmnsn_array *new_leaves,
int comparator)
{
dmnsn_add_priority_leaves(sorted_leaves, nleaves, new_leaves);
dmnsn_bvh_node **right_sorted_leaves[DMNSN_PSEUDO_B];
size_t right_nleaves;
dmnsn_split_sorted_leaves(sorted_leaves, &nleaves,
right_sorted_leaves, &right_nleaves,
buffer, comparator);
if (nleaves > 0) {
dmnsn_priority_leaves_recursive(sorted_leaves, nleaves,
buffer, new_leaves,
(comparator + 1)%DMNSN_PSEUDO_B);
}
if (right_nleaves > 0) {
dmnsn_priority_leaves_recursive(right_sorted_leaves, right_nleaves,
buffer, new_leaves,
(comparator + 1)%DMNSN_PSEUDO_B);
}
}
/** Sort each dimension in parallel with more than this many leaves. */
#define DMNSN_PARALLEL_SORT_THRESHOLD 1024
typedef struct {
dmnsn_bvh_node **leaves_arr;
dmnsn_bvh_node ***sorted_leaves;
size_t nleaves;
} dmnsn_sort_leaves_payload;
static dmnsn_bvh_node **
dmnsn_sort_leaf_array(dmnsn_bvh_node **leaves, size_t nleaves, int comparator)
{
size_t leaves_size = nleaves*sizeof(dmnsn_bvh_node *);
dmnsn_bvh_node **sorted_leaves = dmnsn_malloc(leaves_size);
memcpy(sorted_leaves, leaves, leaves_size);
qsort(sorted_leaves, nleaves, sizeof(dmnsn_bvh_node *),
dmnsn_comparators[comparator]);
return sorted_leaves;
}
static int
dmnsn_sort_leaves(void *ptr, unsigned int thread, unsigned int nthreads)
{
dmnsn_sort_leaves_payload *payload = ptr;
for (unsigned int i = thread; i < DMNSN_PSEUDO_B; i += nthreads) {
payload->sorted_leaves[i] =
dmnsn_sort_leaf_array(payload->leaves_arr, payload->nleaves, i);
}
return 0;
}
/** Constructs an implicit pseudo-PR-tree and returns the priority leaves. */
static dmnsn_array *
dmnsn_priority_leaves(const dmnsn_array *leaves, unsigned int nthreads)
{
dmnsn_bvh_node **leaves_arr = dmnsn_array_first(leaves);
dmnsn_bvh_node **sorted_leaves[DMNSN_PSEUDO_B];
size_t nleaves = dmnsn_array_size(leaves);
if (nleaves >= DMNSN_PARALLEL_SORT_THRESHOLD && nthreads > 1) {
dmnsn_sort_leaves_payload payload = {
.leaves_arr = leaves_arr,
.sorted_leaves = sorted_leaves,
.nleaves = nleaves,
};
dmnsn_execute_concurrently(NULL, dmnsn_sort_leaves, &payload, nthreads);
} else {
for (size_t i = 0; i < DMNSN_PSEUDO_B; ++i) {
sorted_leaves[i] = dmnsn_sort_leaf_array(leaves_arr, nleaves, i);
}
}
size_t buffer_size = nleaves/2;
dmnsn_bvh_node **buffer = dmnsn_malloc(buffer_size*sizeof(dmnsn_bvh_node *));
dmnsn_array *new_leaves = dmnsn_new_array(sizeof(dmnsn_bvh_node *));
dmnsn_priority_leaves_recursive(sorted_leaves, nleaves, buffer, new_leaves,
0);
dmnsn_free(buffer);
for (size_t i = 0; i < DMNSN_PSEUDO_B; ++i) {
dmnsn_free(sorted_leaves[i]);
}
return new_leaves;
}
dmnsn_bvh_node *
dmnsn_new_prtree(const dmnsn_array *objects)
{
if (dmnsn_array_size(objects) == 0) {
return NULL;
}
/* Make the initial array of leaves */
dmnsn_array *leaves = dmnsn_new_array(sizeof(dmnsn_bvh_node *));
DMNSN_ARRAY_FOREACH (dmnsn_object **, object, objects) {
dmnsn_bvh_node *node = dmnsn_new_bvh_leaf_node(*object);
node->data = DMNSN_PRTREE_LEFT; /* Mustn't be _LEAF */
dmnsn_array_push(leaves, &node);
}
unsigned int ncpus = dmnsn_ncpus();
unsigned int nthreads = ncpus < DMNSN_PSEUDO_B ? ncpus : DMNSN_PSEUDO_B;
while (dmnsn_array_size(leaves) > 1) {
dmnsn_array *new_leaves = dmnsn_priority_leaves(leaves, nthreads);
dmnsn_delete_array(leaves);
leaves = new_leaves;
}
dmnsn_bvh_node *root = *(dmnsn_bvh_node **)dmnsn_array_first(leaves);
dmnsn_delete_array(leaves);
return root;
}
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