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authorTavian Barnes <tavianator@tavianator.com>2014-08-19 17:10:03 -0400
committerTavian Barnes <tavianator@tavianator.com>2015-10-25 11:03:56 -0400
commit7b09710392d35fb55b52031d447a542d99fc6b4b (patch)
tree270eb927ee8c52ceeb99926ebf4843704775a610 /libdimension/bvh/prtree.c
parent200c86b91ea7063d35be3bffc11c5da53c054653 (diff)
downloaddimension-7b09710392d35fb55b52031d447a542d99fc6b4b.tar.xz
Modularize the libdimension codebase.
Diffstat (limited to 'libdimension/bvh/prtree.c')
-rw-r--r--libdimension/bvh/prtree.c372
1 files changed, 372 insertions, 0 deletions
diff --git a/libdimension/bvh/prtree.c b/libdimension/bvh/prtree.c
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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 "internal/platform.h"
+#include "internal/prtree.h"
+#include "internal/concurrency.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_color {
+ DMNSN_PRTREE_LEAF, ///< Priority leaf.
+ DMNSN_PRTREE_LEFT, ///< Left child.
+ DMNSN_PRTREE_RIGHT ///< Right child.
+} dmnsn_prnode_color;
+
+/**
+ * A BVH node with associated color. Compared to storing the color in the
+ * \p dmnsn_bvh_node itself, this method has decreased cache performance during
+ * sorting (due to an extra pointer chase), but increased performance during
+ * tree building (because it's much smaller than a full \p dmnsn_bvh_node).
+ * Overall it gives about a 25% improvement.
+ */
+typedef struct dmnsn_colored_prnode {
+ dmnsn_prnode_color color;
+ dmnsn_bvh_node *node;
+} dmnsn_colored_prnode;
+
+/// Construct an empty PR-node.
+static inline dmnsn_bvh_node *
+dmnsn_new_prnode(void)
+{
+ return dmnsn_new_bvh_node(DMNSN_PRTREE_B);
+}
+
+/// 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_colored_prnode **)l)->node->aabb.min.x;
+ double rval = (*(const dmnsn_colored_prnode **)r)->node->aabb.min.x;
+ return (lval > rval) - (lval < rval);
+}
+
+static int
+dmnsn_ymin_comp(const void *l, const void *r)
+{
+ double lval = (*(const dmnsn_colored_prnode **)l)->node->aabb.min.y;
+ double rval = (*(const dmnsn_colored_prnode **)r)->node->aabb.min.y;
+ return (lval > rval) - (lval < rval);
+}
+
+static int
+dmnsn_zmin_comp(const void *l, const void *r)
+{
+ double lval = (*(const dmnsn_colored_prnode **)l)->node->aabb.min.z;
+ double rval = (*(const dmnsn_colored_prnode **)r)->node->aabb.min.z;
+ return (lval > rval) - (lval < rval);
+}
+
+static int
+dmnsn_xmax_comp(const void *l, const void *r)
+{
+ double lval = (*(const dmnsn_colored_prnode **)l)->node->aabb.max.x;
+ double rval = (*(const dmnsn_colored_prnode **)r)->node->aabb.max.x;
+ return (lval < rval) - (lval > rval);
+}
+
+static int
+dmnsn_ymax_comp(const void *l, const void *r)
+{
+ double lval = (*(const dmnsn_colored_prnode **)l)->node->aabb.max.y;
+ double rval = (*(const dmnsn_colored_prnode **)r)->node->aabb.max.y;
+ return (lval < rval) - (lval > rval);
+}
+
+static int
+dmnsn_zmax_comp(const void *l, const void *r)
+{
+ double lval = (*(const dmnsn_colored_prnode **)l)->node->aabb.max.z;
+ double rval = (*(const dmnsn_colored_prnode **)r)->node->aabb.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_colored_prnode **sorted_leaves[DMNSN_PSEUDO_B],
+ size_t start, size_t end,
+ dmnsn_array *new_leaves)
+{
+ for (size_t i = 0; i < DMNSN_PSEUDO_B; ++i) {
+ dmnsn_bvh_node *leaf = NULL;
+ dmnsn_colored_prnode **leaves = sorted_leaves[i];
+
+ for (size_t j = start;
+ j < end && (!leaf || leaf->nchildren < DMNSN_PRTREE_B);
+ ++j) {
+ // Skip all the previously found extreme nodes
+ if (leaves[j]->color == DMNSN_PRTREE_LEAF) {
+ continue;
+ }
+
+ if (!leaf) {
+ leaf = dmnsn_new_prnode();
+ }
+ leaves[j]->color = DMNSN_PRTREE_LEAF;
+ dmnsn_bvh_node_add(leaf, leaves[j]->node);
+ }
+
+ if (leaf) {
+ dmnsn_array_push(new_leaves, &leaf);
+ } else {
+ return;
+ }
+ }
+}
+
+/// Get rid of the extreme nodes.
+static void
+dmnsn_filter_priority_leaves(dmnsn_colored_prnode **leaves, size_t start, size_t *endp)
+{
+ size_t i, skip, end;
+ for (i = start, skip = 0, end = *endp; i < end; ++i) {
+ if (leaves[i]->color == DMNSN_PRTREE_LEAF) {
+ ++skip;
+ } else {
+ leaves[i - skip] = leaves[i];
+ }
+ }
+
+ *endp -= skip;
+}
+
+/// Split the leaves and mark the left and right child nodes.
+static void
+dmnsn_split_sorted_leaves_easy(dmnsn_colored_prnode **leaves, size_t start, size_t *midp, size_t end)
+{
+ size_t i, mid = start + (end - start + 1)/2;
+ for (i = start; i < mid; ++i) {
+ leaves[i]->color = DMNSN_PRTREE_LEFT;
+ }
+ for (; i < end; ++i) {
+ leaves[i]->color = DMNSN_PRTREE_RIGHT;
+ }
+
+ *midp = mid;
+}
+
+/// Split the leaves using the coloring from dmnsn_split_sorted_leaves_easy().
+static void
+dmnsn_split_sorted_leaves_hard(dmnsn_colored_prnode **leaves, dmnsn_colored_prnode **buffer, size_t start, size_t end)
+{
+ size_t i, j, skip;
+ for (i = start, j = 0, skip = 0; i < end; ++i) {
+ if (leaves[i]->color == DMNSN_PRTREE_LEFT) {
+ leaves[i - skip] = leaves[i];
+ } else {
+ if (leaves[i]->color == DMNSN_PRTREE_RIGHT) {
+ buffer[j] = leaves[i];
+ ++j;
+ }
+ ++skip;
+ }
+ }
+
+ size_t mid = i - skip;
+ for (i = 0; i < j; ++i) {
+ leaves[mid + i] = buffer[i];
+ }
+}
+
+/// Split the sorted lists into the left and right subtrees.
+static void
+dmnsn_split_sorted_leaves(dmnsn_colored_prnode **sorted_leaves[DMNSN_PSEUDO_B],
+ size_t start, size_t *midp, size_t *endp,
+ dmnsn_colored_prnode **buffer, int i)
+{
+ size_t orig_end = *endp;
+
+ // Filter the extreme nodes in the ith list
+ dmnsn_filter_priority_leaves(sorted_leaves[i], start, endp);
+
+ // Split the ith list
+ dmnsn_split_sorted_leaves_easy(sorted_leaves[i], start, midp, *endp);
+
+ // Split the rest of the lists
+ for (size_t j = 0; j < DMNSN_PSEUDO_B; ++j) {
+ if (j == i) {
+ continue;
+ }
+
+ dmnsn_split_sorted_leaves_hard(sorted_leaves[j], buffer, start, orig_end);
+ }
+}
+
+/// Recursively constructs an implicit pseudo-PR-tree and collects the priority
+/// leaves.
+static void
+dmnsn_priority_leaves_recursive(dmnsn_colored_prnode **sorted_leaves[DMNSN_PSEUDO_B],
+ size_t start, size_t end,
+ dmnsn_colored_prnode **buffer,
+ dmnsn_array *new_leaves,
+ int comparator)
+{
+ dmnsn_add_priority_leaves(sorted_leaves, start, end, new_leaves);
+
+ size_t mid;
+ dmnsn_split_sorted_leaves(sorted_leaves, start, &mid, &end, buffer, comparator);
+
+ int next = (comparator + 1)%DMNSN_PSEUDO_B;
+
+ if (start < mid) {
+ dmnsn_priority_leaves_recursive(sorted_leaves, start, mid, buffer, new_leaves, next);
+ }
+
+ if (mid < end) {
+ dmnsn_priority_leaves_recursive(sorted_leaves, mid, end, buffer, new_leaves, next);
+ }
+}
+
+/// Sort each dimension in parallel with more than this many leaves.
+#define DMNSN_PARALLEL_SORT_THRESHOLD 1024
+
+typedef struct {
+ dmnsn_colored_prnode *colored_leaves;
+ dmnsn_colored_prnode ***sorted_leaves;
+ size_t nleaves;
+} dmnsn_sort_leaves_payload;
+
+static dmnsn_colored_prnode **
+dmnsn_sort_leaf_array(dmnsn_colored_prnode *colored_leaves, size_t nleaves, int comparator)
+{
+ dmnsn_colored_prnode **sorted_leaves = dmnsn_malloc(nleaves*sizeof(dmnsn_colored_prnode *));
+
+ for (size_t i = 0; i < nleaves; ++i) {
+ sorted_leaves[i] = colored_leaves + i;
+ }
+
+ qsort(sorted_leaves, nleaves, sizeof(dmnsn_colored_prnode *), 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->colored_leaves, 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);
+ size_t nleaves = dmnsn_array_size(leaves);
+
+ dmnsn_colored_prnode *colored_leaves = dmnsn_malloc(nleaves*sizeof(dmnsn_colored_prnode));
+ for (size_t i = 0; i < nleaves; ++i) {
+ colored_leaves[i].color = DMNSN_PRTREE_LEFT; // Mustn't be _LEAF
+ colored_leaves[i].node = leaves_arr[i];
+ }
+
+ dmnsn_colored_prnode **sorted_leaves[DMNSN_PSEUDO_B];
+
+ if (nleaves >= DMNSN_PARALLEL_SORT_THRESHOLD && nthreads > 1) {
+ dmnsn_sort_leaves_payload payload = {
+ .colored_leaves = colored_leaves,
+ .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(colored_leaves, nleaves, i);
+ }
+ }
+
+ size_t buffer_size = nleaves/2;
+ dmnsn_colored_prnode **buffer = dmnsn_malloc(buffer_size*sizeof(dmnsn_colored_prnode *));
+
+ dmnsn_array *new_leaves = DMNSN_NEW_ARRAY(dmnsn_bvh_node *);
+
+ dmnsn_priority_leaves_recursive(sorted_leaves, 0, nleaves, buffer, new_leaves, 0);
+
+ dmnsn_free(buffer);
+ for (size_t i = 0; i < DMNSN_PSEUDO_B; ++i) {
+ dmnsn_free(sorted_leaves[i]);
+ }
+ dmnsn_free(colored_leaves);
+
+ 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(dmnsn_bvh_node *);
+ DMNSN_ARRAY_FOREACH (dmnsn_object **, object, objects) {
+ dmnsn_bvh_node *node = dmnsn_new_bvh_leaf_node(*object);
+ 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;
+}