Modularize the libdimension codebase.

1 files changed, 372 insertions, 0 deletions

diff --git a/libdimension/bvh/prtree.c b/libdimension/bvh/prtree.c
new file mode 100644
index 0000000..c8e4e54
--- /dev/null
+++ b/libdimension/bvh/prtree.c
@@ -0,0 +1,372 @@
+/*************************************************************************
+ * 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;
+}