💿🐜 Antkeeper source code
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239 lines
5.3 KiB
239 lines
5.3 KiB
/*
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* Copyright (C) 2021 Christopher J. Howard
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*
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* This file is part of Antkeeper source code.
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*
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* Antkeeper source code is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Antkeeper source code is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef ANTKEEPER_GEOM_RECT_PACK_HPP
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#define ANTKEEPER_GEOM_RECT_PACK_HPP
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#include "geom/rect.hpp"
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namespace geom {
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/**
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* Node used in 2D rectangle packing.
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*
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* @see geom::rect_pack
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*/
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template <class T>
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struct rect_pack_node
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{
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/// Scalar type.
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typedef T scalar_type;
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/// Rect type.
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typedef rect<T> rect_type;
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/// Creates a rect pack node.
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rect_pack_node();
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/// Destroys a rect pack node and its children.
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~rect_pack_node();
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/// Pointers to the two children of the node, if any.
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rect_pack_node* children[2];
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/// Bounds of the node.
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rect_type bounds;
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/// `true` if the node is occupied, `false` otherwise.
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bool occupied;
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};
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template <class T>
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rect_pack_node<T>::rect_pack_node():
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bounds{T(0), T(0), T(0), T(0)},
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occupied(false)
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{
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children[0] = nullptr;
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children[1] = nullptr;
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}
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template <class T>
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rect_pack_node<T>::~rect_pack_node()
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{
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delete children[0];
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delete children[1];
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}
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/**
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* Packs 2D rectangles.
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*
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* @see geom::rect_pack_node
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*
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* @see http://www.blackpawn.com/texts/lightmaps/
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*/
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template <class T>
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class rect_pack
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{
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public:
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/// Scalar type.
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typedef T scalar_type;
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/// Node type.
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typedef rect_pack_node<T> node_type;
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/**
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* Creates a rect pack and sets the bounds of the root node.
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*
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* @param w Width of the root node.
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* @param h Height of the root node.
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*/
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rect_pack(scalar_type w, scalar_type h);
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/**
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* Creates an empty rect pack.
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*/
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rect_pack();
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/**
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* Clears the pack and resizes the root node bounds.
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*
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* @param w New width of the root node.
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* @param h New height of the root node.
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*
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* @see rect_pack::clear()
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*/
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void resize(scalar_type w, scalar_type h);
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/// Clear the pack, deallocating all nodes.
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void clear();
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/**
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* Packs a rect into the rect pack.
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*
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* @param w Width of the rect.
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* @param h Height of the rect.
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* @return Pointer to the node in which the rect was packed, or `nullptr` if the rect could not be packed.
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*/
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const node_type* pack(scalar_type w, scalar_type h);
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/// Returns a reference to the root node.
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const node_type& get_root() const;
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private:
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static node_type* insert(node_type& parent, scalar_type w, scalar_type h);
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static void free();
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node_type root;
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};
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template <class T>
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rect_pack<T>::rect_pack(scalar_type w, scalar_type h)
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{
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root.bounds = {T(0), T(0), w, h};
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}
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template <class T>
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rect_pack<T>::rect_pack():
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rect_pack(0, 0)
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{}
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template <class T>
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void rect_pack<T>::resize(scalar_type w, scalar_type h)
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{
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clear();
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root.bounds = {T(0), T(0), w, h};
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}
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template <class T>
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void rect_pack<T>::clear()
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{
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delete root.children[0];
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delete root.children[1];
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root.children[0] = nullptr;
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root.children[1] = nullptr;
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root.occupied = false;
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}
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template <class T>
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const typename rect_pack<T>::node_type* rect_pack<T>::pack(scalar_type w, scalar_type h)
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{
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return insert(root, w, h);
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}
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template <class T>
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inline const typename rect_pack<T>::node_type& rect_pack<T>::get_root() const
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{
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return root;
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}
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template <class T>
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typename rect_pack<T>::node_type* rect_pack<T>::insert(node_type& node, scalar_type w, scalar_type h)
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{
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// If not a leaf node
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if (node.children[0] && node.children[1])
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{
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// Attempt to insert into first child
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node_type* result = insert(*node.children[0], w, h);
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if (result)
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return result;
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// Cannot fit in first child, attempt to insert into second child
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return insert(*node.children[1], w, h);
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}
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// Abort if node occupied
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if (node.occupied)
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return nullptr;
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// Determine node dimensions
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scalar_type node_w = node.bounds.max.x - node.bounds.min.x;
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scalar_type node_h = node.bounds.max.y - node.bounds.min.y;
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// Check if rect is larger than node
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if (w > node_w || h > node_h)
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return nullptr;
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// Check for a perfect fit
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if (w == node_w && h == node_h)
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{
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node.occupied = true;
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return &node;
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}
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// Split the node
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node.children[0] = new node_type();
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node.children[1] = new node_type();
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// Determine split direction
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scalar_type dw = node_w - w;
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scalar_type dh = node_h - h;
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if (dw > dh)
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{
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node.children[0]->bounds.min = node.bounds.min;
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node.children[0]->bounds.max = {node.bounds.min.x + w, node.bounds.max.y};
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node.children[1]->bounds.min = {node.bounds.min.x + w, node.bounds.min.y};
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node.children[1]->bounds.max = {node.bounds.max};
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}
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else
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{
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node.children[0]->bounds.min = node.bounds.min;
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node.children[0]->bounds.max = {node.bounds.max.x, node.bounds.min.y + h};
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node.children[1]->bounds.min = {node.bounds.min.x, node.bounds.min.y + h};
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node.children[1]->bounds.max = {node.bounds.max};
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}
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// Insert into first child
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return insert(*node.children[0], w, h);
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}
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} // namespace geom
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#endif // ANTKEEPER_GEOM_RECT_PACK_HPP
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