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- /*
- * Copyright (C) 2023 Christopher J. Howard
- *
- * This file is part of Antkeeper source code.
- *
- * Antkeeper source code is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * Antkeeper source code 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 General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
- */
-
- #ifndef ANTKEEPER_GEOM_RECT_PACK_HPP
- #define ANTKEEPER_GEOM_RECT_PACK_HPP
-
- #include <engine/geom/primitives/rectangle.hpp>
- #include <memory>
-
- namespace geom {
-
- /**
- * Node used in 2D rectangle packing.
- *
- * @see geom::rect_pack
- */
- template <class T>
- struct rect_pack_node
- {
- /// Scalar type.
- using scalar_type = T;
-
- /// Rect type.
- using rect_type = rectangle<T>;
-
- /// Pointers to the two children of the node, if any.
- std::unique_ptr<rect_pack_node> children[2];
-
- /// Bounds of the node.
- rect_type bounds{{T{0}, T{0}}, {T{0}, T{0}}};
-
- /// `true` if the node is occupied, `false` otherwise.
- bool occupied{false};
- };
-
- /**
- * Packs 2D rectangles.
- *
- * @see geom::rect_pack_node
- *
- * @see http://www.blackpawn.com/texts/lightmaps/
- */
- template <class T>
- class rect_pack
- {
- public:
- /// Scalar type.
- using scalar_type = T;
-
- /// Node type.
- using node_type = rect_pack_node<T>;
-
- /**
- * Creates a rect pack and sets the bounds of the root node.
- *
- * @param w Width of the root node.
- * @param h Height of the root node.
- */
- rect_pack(scalar_type w, scalar_type h);
-
- /**
- * Creates an empty rect pack.
- */
- rect_pack();
-
- /**
- * Clears the pack and resizes the root node bounds.
- *
- * @param w New width of the root node.
- * @param h New height of the root node.
- *
- * @see rect_pack::clear()
- */
- void resize(scalar_type w, scalar_type h);
-
- /// Clear the pack, deallocating all nodes.
- void clear();
-
- /**
- * Packs a rect into the rect pack.
- *
- * @param w Width of the rect.
- * @param h Height of the rect.
- * @return Pointer to the node in which the rect was packed, or `nullptr` if the rect could not be packed.
- */
- const node_type* pack(scalar_type w, scalar_type h);
-
- /// Returns a reference to the root node.
- const node_type& get_root() const;
-
- private:
- static node_type* insert(node_type& parent, scalar_type w, scalar_type h);
-
- static void free();
-
- node_type root;
- };
-
- template <class T>
- rect_pack<T>::rect_pack(scalar_type w, scalar_type h)
- {
- root.bounds = {T{0}, T{0}, w, h};
- }
-
- template <class T>
- rect_pack<T>::rect_pack():
- rect_pack(0, 0)
- {}
-
- template <class T>
- void rect_pack<T>::resize(scalar_type w, scalar_type h)
- {
- clear();
- root.bounds = {{T{0}, T{0}}, {w, h}};
- }
-
- template <class T>
- void rect_pack<T>::clear()
- {
- root.children[0].reset();
- root.children[1].reset();
- root.occupied = false;
- }
-
- template <class T>
- const typename rect_pack<T>::node_type* rect_pack<T>::pack(scalar_type w, scalar_type h)
- {
- return insert(root, w, h);
- }
-
- template <class T>
- inline const typename rect_pack<T>::node_type& rect_pack<T>::get_root() const
- {
- return root;
- }
-
- template <class T>
- typename rect_pack<T>::node_type* rect_pack<T>::insert(node_type& node, scalar_type w, scalar_type h)
- {
- // If not a leaf node
- if (node.children[0] && node.children[1])
- {
- // Attempt to insert into first child
- node_type* result = insert(*node.children[0], w, h);
- if (result)
- {
- return result;
- }
-
- // Cannot fit in first child, attempt to insert into second child
- return insert(*node.children[1], w, h);
-
- }
-
- // Abort if node occupied
- if (node.occupied)
- {
- return nullptr;
- }
-
- // Determine node dimensions
- scalar_type node_w = node.bounds.max.x() - node.bounds.min.x();
- scalar_type node_h = node.bounds.max.y() - node.bounds.min.y();
-
- // Check if rect is larger than node
- if (w > node_w || h > node_h)
- {
- return nullptr;
- }
-
- // Check for a perfect fit
- if (w == node_w && h == node_h)
- {
- node.occupied = true;
- return &node;
- }
-
- // Split the node
- node.children[0] = std::make_unique<node_type>();
- node.children[1] = std::make_unique<node_type>();
-
- // Determine split direction
- scalar_type dw = node_w - w;
- scalar_type dh = node_h - h;
- if (dw > dh)
- {
- node.children[0]->bounds.min = node.bounds.min;
- node.children[0]->bounds.max = {node.bounds.min.x() + w, node.bounds.max.y()};
- node.children[1]->bounds.min = {node.bounds.min.x() + w, node.bounds.min.y()};
- node.children[1]->bounds.max = {node.bounds.max};
- }
- else
- {
- node.children[0]->bounds.min = node.bounds.min;
- node.children[0]->bounds.max = {node.bounds.max.x(), node.bounds.min.y() + h};
- node.children[1]->bounds.min = {node.bounds.min.x(), node.bounds.min.y() + h};
- node.children[1]->bounds.max = {node.bounds.max};
- }
-
- // Insert into first child
- return insert(*node.children[0], w, h);
- }
-
- } // namespace geom
-
- #endif // ANTKEEPER_GEOM_RECT_PACK_HPP
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