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/*
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Quirky Quad Trees Part #1 - Static Quad Tree Implementation |
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"War... huh... What is it good for? Absolutely nothin..." - javidx9 |
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License (OLC-3) |
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~~~~~~~~~~~~~~~ |
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Copyright 2018 - 2022 OneLoneCoder.com |
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Redistribution and use in source and binary forms, with or without |
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modification, are permitted provided that the following conditions |
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are met: |
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1. Redistributions or derivations of source code must retain the above |
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copyright notice, this list of conditions and the following disclaimer. |
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2. Redistributions or derivative works in binary form must reproduce |
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the above copyright notice. This list of conditions and the following |
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disclaimer must be reproduced in the documentation and/or other |
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materials provided with the distribution. |
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|
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3. Neither the name of the copyright holder nor the names of its |
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contributors may be used to endorse or promote products derived |
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from this software without specific prior written permission. |
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
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HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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Video: |
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~~~~~~ |
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https://youtu.be/ASAowY6yJII
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Pan & Zoom with middle mouse, TAB to switch between methods |
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Links |
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~~~~~ |
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YouTube: https://www.youtube.com/javidx9
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https://www.youtube.com/javidx9extra
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Discord: https://discord.gg/WhwHUMV
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Twitter: https://www.twitter.com/javidx9
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Twitch: https://www.twitch.tv/javidx9
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GitHub: https://www.github.com/onelonecoder
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Homepage: https://www.onelonecoder.com
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Author |
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~~~~~~ |
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David Barr, aka javidx9, ©OneLoneCoder 2019, 2020, 2021, 2022 |
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*/ |
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#define OLC_PGE_APPLICATION |
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#include "olcPixelGameEngine.h" |
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#define OLC_PGEX_TRANSFORMEDVIEW |
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#include "olcPGEX_TransformedView.h" |
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namespace olc |
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{ |
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struct rect |
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{ |
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olc::vf2d pos; |
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olc::vf2d size; |
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rect(const olc::vf2d& p = { 0.0f, 0.0f }, const olc::vf2d& s = { 1.0f, 1.0f }) : pos(p), size(s) |
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{ |
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} |
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constexpr bool contains(const olc::vf2d& p) const |
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{ |
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return !(p.x < pos.x || p.y < pos.y || p.x >= (pos.x + size.x) || p.y >= (pos.y + size.y)); |
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} |
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constexpr bool contains(const olc::rect& r) const |
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{ |
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return (r.pos.x >= pos.x) && (r.pos.x + r.size.x < pos.x + size.x) && |
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(r.pos.y >= pos.y) && (r.pos.y + r.size.y < pos.y + size.y); |
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} |
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constexpr bool overlaps(const olc::rect& r) const |
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{ |
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return (pos.x < r.pos.x + r.size.x && pos.x + size.x >= r.pos.x && pos.y < r.pos.y + r.size.y && pos.y + size.y >= r.pos.y); |
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} |
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}; |
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}; |
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// Constrain depth of Quad Tree. Since its floating point, it could in principle sub-divide for
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// a very long time, consuming far more time and memory than is sensible
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constexpr size_t MAX_DEPTH = 8; |
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template <typename OBJECT_TYPE> |
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class StaticQuadTree |
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{ |
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public: |
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StaticQuadTree(const olc::rect& size = { {0.0f, 0.0f}, {100.0f, 100.0f} }, const size_t nDepth = 0) |
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{ |
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m_depth = nDepth; |
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resize(size); |
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} |
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// Force area change on Tree, invalidates this and all child layers
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void resize(const olc::rect& rArea) |
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{ |
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// Erase this layer
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clear(); |
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// Recalculate area of children
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m_rect = rArea; |
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olc::vf2d vChildSize = m_rect.size / 2.0f; |
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// Cache child areas local to this layer
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m_rChild = |
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{ |
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// Top Left
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olc::rect(m_rect.pos, vChildSize), |
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// Top Right
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olc::rect({m_rect.pos.x + vChildSize.x, m_rect.pos.y}, vChildSize), |
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// Bottom Left
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olc::rect({m_rect.pos.x, m_rect.pos.y + vChildSize.y}, vChildSize), |
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// Bottom Right
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olc::rect(m_rect.pos + vChildSize, vChildSize) |
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}; |
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} |
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// Clears the contents of this layer, and all child layers
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void clear() |
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{ |
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// Erase any items stored in this layer
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m_pItems.clear(); |
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// Iterate through children, erase them too
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for (int i = 0; i < 4; i++) |
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{ |
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if (m_pChild[i]) |
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m_pChild[i]->clear(); |
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m_pChild[i].reset(); |
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} |
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} |
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// Returns a count of how many items are stored in this layer, and all children of this layer
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size_t size() const |
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{ |
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size_t nCount = m_pItems.size(); |
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for (int i = 0; i < 4; i++) |
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if (m_pChild[i]) nCount += m_pChild[i]->size(); |
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return nCount; |
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} |
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// Inserts an object into this layer (or appropriate child layer), given the area the item occupies
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void insert(const OBJECT_TYPE& item, const olc::rect& itemsize) |
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{ |
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// Check each child
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for (int i = 0; i < 4; i++) |
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{ |
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// If the child can wholly contain the item being inserted
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if (m_rChild[i].contains(itemsize)) |
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{ |
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// Have we reached depth limit?
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if (m_depth + 1 < MAX_DEPTH) |
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{ |
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// No, so does child exist?
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if (!m_pChild[i]) |
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{ |
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// No, so create it
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m_pChild[i] = std::make_shared<StaticQuadTree<OBJECT_TYPE>>(m_rChild[i], m_depth + 1); |
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} |
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// Yes, so add item to it
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m_pChild[i]->insert(item, itemsize); |
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return; |
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} |
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} |
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} |
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// It didnt fit, so item must belong to this quad
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m_pItems.push_back({ itemsize, item }); |
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} |
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// Returns a list of objects in the given search area
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std::list<OBJECT_TYPE> search(const olc::rect& rArea) const |
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{ |
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std::list<OBJECT_TYPE> listItems; |
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search(rArea, listItems); |
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return listItems; |
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} |
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// Returns the objects in the given search area, by adding to supplied list
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void search(const olc::rect& rArea, std::list<OBJECT_TYPE>& listItems) const |
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{ |
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// First, check for items belonging to this area, add them to the list
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// if there is overlap
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for (const auto& p : m_pItems) |
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{ |
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if (rArea.overlaps(p.first)) |
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listItems.push_back(p.second); |
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} |
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// Second, recurse through children and see if they can
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// add to the list
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for (int i = 0; i < 4; i++) |
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{ |
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if (m_pChild[i]) |
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{ |
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// If child is entirely contained within area, recursively
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// add all of its children, no need to check boundaries
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if (rArea.contains(m_rChild[i])) |
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m_pChild[i]->items(listItems); |
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// If child overlaps with search area then checks need
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// to be made
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else if (m_rChild[i].overlaps(rArea)) |
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m_pChild[i]->search(rArea, listItems); |
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} |
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} |
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} |
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void items(std::list<OBJECT_TYPE>& listItems) const |
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{ |
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// No questions asked, just return child items
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for (const auto& p : m_pItems) |
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listItems.push_back(p.second); |
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// Now add children of this layer's items
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for (int i = 0; i < 4; i++) |
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if (m_pChild[i]) m_pChild[i]->items(listItems); |
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} |
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std::list<OBJECT_TYPE> items() const |
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{ |
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// No questions asked, just return child items
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std::list<OBJECT_TYPE> listItems; |
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items(listItems); |
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return listItems; |
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} |
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// Returns area of this layer
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const olc::rect& area() |
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{ |
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return m_rect; |
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} |
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protected: |
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// Depth of this StaticQuadTree layer
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size_t m_depth = 0; |
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// Area of this StaticQuadTree
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olc::rect m_rect; |
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// 4 child areas of this StaticQuadTree
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std::array<olc::rect, 4> m_rChild{}; |
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// 4 potential children of this StaticQuadTree
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std::array<std::shared_ptr<StaticQuadTree<OBJECT_TYPE>>, 4> m_pChild{}; |
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// Items which belong to this StaticQuadTree
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std::vector<std::pair<olc::rect, OBJECT_TYPE>> m_pItems; |
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}; |
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template <typename OBJECT_TYPE> |
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class StaticQuadTreeContainer |
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{ |
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// Using a std::list as we dont want pointers to be invalidated to objects stored in the
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// tree should the contents of the tree change
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using QuadTreeContainer = std::list<OBJECT_TYPE>; |
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protected: |
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// The actual container
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QuadTreeContainer m_allItems; |
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// Use our StaticQuadTree to store "pointers" instead of objects - this reduces
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// overheads when moving or copying objects
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StaticQuadTree<typename QuadTreeContainer::iterator> root; |
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public: |
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StaticQuadTreeContainer(const olc::rect& size = { {0.0f, 0.0f}, { 100.0f, 100.0f } }, const size_t nDepth = 0) : root(size, nDepth) |
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{ |
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} |
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// Sets the spatial coverage area of the quadtree
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// Invalidates tree
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void resize(const olc::rect& rArea) |
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{ |
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root.resize(rArea); |
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} |
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// Returns number of items within tree
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size_t size() const |
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{ |
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return m_allItems.size(); |
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} |
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// Returns true if tree is empty
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bool empty() const |
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{ |
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return m_allItems.empty(); |
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} |
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// Removes all items from tree
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void clear() |
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{ |
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root.clear(); |
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m_allItems.clear(); |
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} |
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// Convenience functions for ranged for loop
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typename QuadTreeContainer::iterator begin() |
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{ |
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return m_allItems.begin(); |
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} |
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typename QuadTreeContainer::iterator end() |
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{ |
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return m_allItems.end(); |
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} |
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typename QuadTreeContainer::const_iterator cbegin() |
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{ |
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return m_allItems.cbegin(); |
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} |
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typename QuadTreeContainer::const_iterator cend() |
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{ |
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return m_allItems.cend(); |
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} |
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// Insert item into tree in specified area
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void insert(const OBJECT_TYPE& item, const olc::rect& itemsize) |
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{ |
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// Item is stored in container
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m_allItems.push_back(item); |
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// Pointer/Area of item is stored in quad tree
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root.insert(std::prev(m_allItems.end()), itemsize); |
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} |
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// Returns a std::list of pointers to items within the search area
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std::list<typename QuadTreeContainer::iterator> search(const olc::rect& rArea) const |
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{ |
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std::list<typename QuadTreeContainer::iterator> listItemPointers; |
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root.search(rArea, listItemPointers); |
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return listItemPointers; |
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} |
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}; |
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// The Example!
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class Example_StaticQuadTree : public olc::PixelGameEngine |
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{ |
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public: |
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Example_StaticQuadTree() |
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{ |
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sAppName = "Static QuadTree"; |
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} |
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protected: |
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olc::TransformedView tv; |
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// An example object of something in 2D space
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struct SomeObjectWithArea |
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{ |
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olc::vf2d vPos; |
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olc::vf2d vVel; |
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olc::vf2d vSize; |
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olc::Pixel colour; |
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}; |
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// A regular list of the objects
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std::list<SomeObjectWithArea> vecObjects; |
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// An equivalent quad tree of the objects
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StaticQuadTreeContainer<SomeObjectWithArea> treeObjects; |
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// The "length" of one side of the "world" the objects reside in
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float fArea = 100000.0f; |
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bool bUseQuadTree = true; |
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public: |
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bool OnUserCreate() override |
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{ |
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// Transform View - enables Pan & Zoom
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tv.Initialise({ ScreenWidth(), ScreenHeight() }); |
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// Create the tree, and size it to the world
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treeObjects.resize(olc::rect({ 0.0f, 0.0f }, { fArea, fArea })); |
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// Dirty random float generator
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auto rand_float = [](const float a, const float b) |
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{ |
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return float(rand()) / float(RAND_MAX) * (b - a) + a; |
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}; |
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// Create 1,000,000 objects, push into both containers (so 2,000,000 I suppose :P )
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for (int i = 0; i < 1000000; i++) |
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{ |
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SomeObjectWithArea ob; |
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ob.vPos = { rand_float(0.0f, fArea), rand_float(0.0f, fArea) }; |
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ob.vSize = { rand_float(0.1f, 100.0f), rand_float(0.1f, 100.0f) }; |
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ob.colour = olc::Pixel(rand() % 256, rand() % 256, rand() % 256); |
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treeObjects.insert(ob, olc::rect(ob.vPos, ob.vSize)); |
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vecObjects.push_back(ob); |
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} |
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return true; |
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} |
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bool OnUserUpdate(float fElapsedTime) override |
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{ |
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// Tab switches between modes
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if (GetKey(olc::Key::TAB).bPressed) |
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bUseQuadTree = !bUseQuadTree; |
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tv.HandlePanAndZoom(); |
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// Get rectangle that equates to screen in world space
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olc::rect rScreen = { tv.GetWorldTL(), tv.GetWorldBR() - tv.GetWorldTL() }; |
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size_t nObjectCount = 0; |
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if (bUseQuadTree) |
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{ |
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// QUAD TREE MODE
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auto tpStart = std::chrono::system_clock::now(); |
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// Use search function to return list of pointers to objects in that area
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for (const auto& object : treeObjects.search(rScreen)) |
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{ |
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tv.FillRectDecal(object->vPos, object->vSize, object->colour); |
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nObjectCount++; |
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} |
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std::chrono::duration<float> duration = std::chrono::system_clock::now() - tpStart; |
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std::string sOutput = "Quadtree " + std::to_string(nObjectCount) + "/" + std::to_string(vecObjects.size()) + " in " + std::to_string(duration.count()); |
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DrawStringDecal({ 4, 4 }, sOutput, olc::BLACK, { 4.0f, 8.0f }); |
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DrawStringDecal({ 2, 2 }, sOutput, olc::WHITE, { 4.0f, 8.0f }); |
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} |
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else |
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{ |
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// LINEAR SEARCH MODE
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auto tpStart = std::chrono::system_clock::now(); |
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// Blindly check all objects to see if they overlap with screen
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for (const auto& object : vecObjects) |
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{ |
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if (rScreen.overlaps({ object.vPos, object.vSize })) |
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{ |
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tv.FillRectDecal(object.vPos, object.vSize, object.colour); |
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nObjectCount++; |
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} |
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} |
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std::chrono::duration<float> duration = std::chrono::system_clock::now() - tpStart; |
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std::string sOutput = "Linear " + std::to_string(nObjectCount) + "/" + std::to_string(vecObjects.size()) + " in " + std::to_string(duration.count()); |
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DrawStringDecal({ 4, 4 }, sOutput, olc::BLACK, { 4.0f, 8.0f }); |
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DrawStringDecal({ 2, 2 }, sOutput, olc::WHITE, { 4.0f, 8.0f }); |
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} |
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return true; |
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} |
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}; |
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int main() |
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{ |
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Example_StaticQuadTree demo; |
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if (demo.Construct(1280, 960, 1, 1, false, false)) |
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demo.Start(); |
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return 0; |
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} |
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Reference in new issue