Added QuadTree Part1 Code

Videos/OneLoneCoder_PGE_QuadTree1.cpp

@@ -0,0 +1,493 @@
+/*
+	Quirky Quad Trees Part #1 - Static Quad Tree Implementation
+	"War... huh... What is it good for? Absolutely nothin..." - javidx9
+	
+	License (OLC-3)
+	~~~~~~~~~~~~~~~
+	Copyright 2018 - 2022 OneLoneCoder.com
+
+	Redistribution and use in source and binary forms, with or without
+	modification, are permitted provided that the following conditions
+	are met:
+
+	1. Redistributions or derivations of source code must retain the above
+	copyright notice, this list of conditions and the following disclaimer.
+
+	2. Redistributions or derivative works in binary form must reproduce
+	the above copyright notice. This list of conditions and the following
+	disclaimer must be reproduced in the documentation and/or other
+	materials provided with the distribution.
+
+	3. Neither the name of the copyright holder nor the names of its
+	contributors may be used to endorse or promote products derived
+	from this software without specific prior written permission.
+	THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+	"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+	LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+	A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+	HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+	SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+	LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+	DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+	THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+	(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+	OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+	
+	Video:
+	~~~~~~
+	https://youtu.be/ASAowY6yJII
+
+	Pan & Zoom with middle mouse, TAB to switch between methods
+	
+	Links
+	~~~~~
+	YouTube:	https://www.youtube.com/javidx9
+				https://www.youtube.com/javidx9extra
+	Discord:	https://discord.gg/WhwHUMV
+	Twitter:	https://www.twitter.com/javidx9
+	Twitch:		https://www.twitch.tv/javidx9
+	GitHub:		https://www.github.com/onelonecoder
+	Homepage:	https://www.onelonecoder.com
+	
+	Author
+	~~~~~~
+	David Barr, aka javidx9, ©OneLoneCoder 2019, 2020, 2021, 2022
+*/
+
+
+#define OLC_PGE_APPLICATION
+#include "olcPixelGameEngine.h"
+
+#define OLC_PGEX_TRANSFORMEDVIEW
+#include "olcPGEX_TransformedView.h"
+
+namespace olc
+{
+	struct rect
+	{
+		olc::vf2d pos;
+		olc::vf2d size;
+
+		rect(const olc::vf2d& p = { 0.0f, 0.0f }, const olc::vf2d& s = { 1.0f, 1.0f }) : pos(p), size(s)
+		{
+
+		}
+
+		constexpr bool contains(const olc::vf2d& p) const
+		{
+			return !(p.x < pos.x || p.y < pos.y || p.x >= (pos.x + size.x) || p.y >= (pos.y + size.y));
+		}
+
+		constexpr bool contains(const olc::rect& r) const
+		{
+			return (r.pos.x >= pos.x) && (r.pos.x + r.size.x < pos.x + size.x) &&
+				(r.pos.y >= pos.y) && (r.pos.y + r.size.y < pos.y + size.y);
+		}
+
+		constexpr bool overlaps(const olc::rect& r) const
+		{
+			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);
+		}
+	};
+
+};
+
+
+// Constrain depth of Quad Tree. Since its floating point, it could in principle sub-divide for
+// a very long time, consuming far more time and memory than is sensible
+constexpr size_t MAX_DEPTH = 8;
+
+
+template <typename OBJECT_TYPE>
+class StaticQuadTree
+{
+public:
+	StaticQuadTree(const olc::rect& size = { {0.0f, 0.0f}, {100.0f, 100.0f} }, const size_t nDepth = 0)
+	{
+		m_depth = nDepth;
+		resize(size);
+	}
+
+	// Force area change on Tree, invalidates this and all child layers
+	void resize(const olc::rect& rArea)
+	{
+		// Erase this layer
+		clear();
+
+		// Recalculate area of children
+		m_rect = rArea;
+		olc::vf2d vChildSize = m_rect.size / 2.0f;
+
+		// Cache child areas local to this layer
+		m_rChild =
+		{
+			// Top Left
+			olc::rect(m_rect.pos, vChildSize),
+			// Top Right
+			olc::rect({m_rect.pos.x + vChildSize.x, m_rect.pos.y}, vChildSize),
+			// Bottom Left
+			olc::rect({m_rect.pos.x, m_rect.pos.y + vChildSize.y}, vChildSize),
+			// Bottom Right
+			olc::rect(m_rect.pos + vChildSize, vChildSize)
+		};
+
+	}
+
+	// Clears the contents of this layer, and all child layers
+	void clear()
+	{
+		// Erase any items stored in this layer
+		m_pItems.clear();
+
+		// Iterate through children, erase them too
+		for (int i = 0; i < 4; i++)
+		{
+			if (m_pChild[i])
+				m_pChild[i]->clear();
+			m_pChild[i].reset();
+		}
+	}
+
+	// Returns a count of how many items are stored in this layer, and all children of this layer
+	size_t size() const
+	{
+		size_t nCount = m_pItems.size();
+		for (int i = 0; i < 4; i++)
+			if (m_pChild[i]) nCount += m_pChild[i]->size();
+		return nCount;
+	}
+
+	// Inserts an object into this layer (or appropriate child layer), given the area the item occupies
+	void insert(const OBJECT_TYPE& item, const olc::rect& itemsize)
+	{
+		// Check each child
+		for (int i = 0; i < 4; i++)
+		{
+			// If the child can wholly contain the item being inserted
+			if (m_rChild[i].contains(itemsize))
+			{
+				// Have we reached depth limit?
+				if (m_depth + 1 < MAX_DEPTH)
+				{
+					// No, so does child exist?
+					if (!m_pChild[i])
+					{
+						// No, so create it
+						m_pChild[i] = std::make_shared<StaticQuadTree<OBJECT_TYPE>>(m_rChild[i], m_depth + 1);
+					}
+
+					// Yes, so add item to it
+					m_pChild[i]->insert(item, itemsize);
+					return;
+				}
+			}
+		}
+
+		// It didnt fit, so item must belong to this quad
+		m_pItems.push_back({ itemsize, item });
+	}
+
+	// Returns a list of objects in the given search area
+	std::list<OBJECT_TYPE> search(const olc::rect& rArea) const
+	{
+		std::list<OBJECT_TYPE> listItems;
+		search(rArea, listItems);
+		return listItems;
+	}
+
+	// Returns the objects in the given search area, by adding to supplied list
+	void search(const olc::rect& rArea, std::list<OBJECT_TYPE>& listItems) const
+	{
+		// First, check for items belonging to this area, add them to the list
+		// if there is overlap
+		for (const auto& p : m_pItems)
+		{
+			if (rArea.overlaps(p.first))
+				listItems.push_back(p.second);
+		}
+
+		// Second, recurse through children and see if they can
+		// add to the list
+		for (int i = 0; i < 4; i++)
+		{
+			if (m_pChild[i])
+			{
+				// If child is entirely contained within area, recursively
+				// add all of its children, no need to check boundaries
+				if (rArea.contains(m_rChild[i]))
+					m_pChild[i]->items(listItems);
+
+				// If child overlaps with search area then checks need
+				// to be made
+				else if (m_rChild[i].overlaps(rArea))
+					m_pChild[i]->search(rArea, listItems);
+			}
+		}
+	}
+
+	void items(std::list<OBJECT_TYPE>& listItems) const
+	{
+		// No questions asked, just return child items
+		for (const auto& p : m_pItems)
+			listItems.push_back(p.second);
+
+		// Now add children of this layer's items
+		for (int i = 0; i < 4; i++)
+			if (m_pChild[i]) m_pChild[i]->items(listItems);
+	}
+
+
+	std::list<OBJECT_TYPE> items() const
+	{
+		// No questions asked, just return child items
+		std::list<OBJECT_TYPE> listItems;
+		items(listItems);
+		return listItems;
+	}
+
+	// Returns area of this layer
+	const olc::rect& area()
+	{
+		return m_rect;
+	}
+
+
+protected:
+	// Depth of this StaticQuadTree layer
+	size_t m_depth = 0;
+
+	// Area of this StaticQuadTree
+	olc::rect m_rect;
+
+	// 4 child areas of this StaticQuadTree
+	std::array<olc::rect, 4> m_rChild{};
+
+	// 4 potential children of this StaticQuadTree
+	std::array<std::shared_ptr<StaticQuadTree<OBJECT_TYPE>>, 4> m_pChild{};
+
+	// Items which belong to this StaticQuadTree
+	std::vector<std::pair<olc::rect, OBJECT_TYPE>> m_pItems;
+};
+
+
+template <typename OBJECT_TYPE>
+class StaticQuadTreeContainer
+{
+	// Using a std::list as we dont want pointers to be invalidated to objects stored in the
+	// tree should the contents of the tree change
+	using QuadTreeContainer = std::list<OBJECT_TYPE>;
+
+protected:
+	// The actual container
+	QuadTreeContainer m_allItems;
+
+	// Use our StaticQuadTree to store "pointers" instead of objects - this reduces
+	// overheads when moving or copying objects 
+	StaticQuadTree<typename QuadTreeContainer::iterator> root;
+
+public:
+	StaticQuadTreeContainer(const olc::rect& size = { {0.0f, 0.0f}, { 100.0f, 100.0f } }, const size_t nDepth = 0) : root(size, nDepth)
+	{
+
+	}
+
+	// Sets the spatial coverage area of the quadtree
+	// Invalidates tree
+	void resize(const olc::rect& rArea)
+	{
+		root.resize(rArea);
+	}
+
+	// Returns number of items within tree
+	size_t size() const
+	{
+		return m_allItems.size();
+	}
+
+	// Returns true if tree is empty
+	bool empty() const
+	{
+		return m_allItems.empty();
+	}
+
+	// Removes all items from tree
+	void clear()
+	{
+		root.clear();
+		m_allItems.clear();
+	}
+
+
+	// Convenience functions for ranged for loop
+	typename QuadTreeContainer::iterator begin()
+	{
+		return m_allItems.begin();
+	}
+
+	typename QuadTreeContainer::iterator end()
+	{
+		return m_allItems.end();
+	}
+
+	typename QuadTreeContainer::const_iterator cbegin()
+	{
+		return m_allItems.cbegin();
+	}
+
+	typename QuadTreeContainer::const_iterator cend()
+	{
+		return m_allItems.cend();
+	}
+
+
+	// Insert item into tree in specified area
+	void insert(const OBJECT_TYPE& item, const olc::rect& itemsize)
+	{
+		// Item is stored in container
+		m_allItems.push_back(item);
+
+		// Pointer/Area of item is stored in quad tree
+		root.insert(std::prev(m_allItems.end()), itemsize);
+	}
+
+	// Returns a std::list of pointers to items within the search area
+	std::list<typename QuadTreeContainer::iterator> search(const olc::rect& rArea) const
+	{
+		std::list<typename QuadTreeContainer::iterator> listItemPointers;
+		root.search(rArea, listItemPointers);
+		return listItemPointers;
+	}
+
+};
+
+
+
+
+// The Example!
+class Example_StaticQuadTree : public olc::PixelGameEngine
+{
+public:
+	Example_StaticQuadTree()
+	{
+		sAppName = "Static QuadTree";
+	}
+
+protected:
+	olc::TransformedView tv;
+
+	// An example object of something in 2D space
+	struct SomeObjectWithArea
+	{
+		olc::vf2d vPos;
+		olc::vf2d vVel;
+		olc::vf2d vSize;
+		olc::Pixel colour;
+	};
+
+	// A regular list of the objects
+	std::list<SomeObjectWithArea> vecObjects;
+
+	// An equivalent quad tree of the objects
+	StaticQuadTreeContainer<SomeObjectWithArea> treeObjects;
+
+	// The "length" of one side of the "world" the objects reside in
+	float fArea = 100000.0f;
+
+	bool bUseQuadTree = true;
+
+public:
+	bool OnUserCreate() override
+	{
+		// Transform View - enables Pan & Zoom
+		tv.Initialise({ ScreenWidth(), ScreenHeight() });
+
+		// Create the tree, and size it to the world
+		treeObjects.resize(olc::rect({ 0.0f, 0.0f }, { fArea, fArea }));
+
+
+		// Dirty random float generator
+		auto rand_float = [](const float a, const float b)
+		{
+			return float(rand()) / float(RAND_MAX) * (b - a) + a;
+		};
+
+
+		// Create 1,000,000 objects, push into both containers (so 2,000,000 I suppose :P )
+		for (int i = 0; i < 1000000; i++)
+		{
+			SomeObjectWithArea ob;
+			ob.vPos = { rand_float(0.0f, fArea), rand_float(0.0f, fArea) };
+			ob.vSize = { rand_float(0.1f, 100.0f), rand_float(0.1f, 100.0f) };
+			ob.colour = olc::Pixel(rand() % 256, rand() % 256, rand() % 256);
+
+			treeObjects.insert(ob, olc::rect(ob.vPos, ob.vSize));
+			vecObjects.push_back(ob);
+		}
+
+		return true;
+	}
+
+	bool OnUserUpdate(float fElapsedTime) override
+	{
+		// Tab switches between modes
+		if (GetKey(olc::Key::TAB).bPressed)
+			bUseQuadTree = !bUseQuadTree;
+
+		tv.HandlePanAndZoom();
+
+		// Get rectangle that equates to screen in world space
+		olc::rect rScreen = { tv.GetWorldTL(), tv.GetWorldBR() - tv.GetWorldTL() };
+		size_t nObjectCount = 0;
+
+		if (bUseQuadTree)
+		{
+			// QUAD TREE MODE
+			auto tpStart = std::chrono::system_clock::now();
+
+			// Use search function to return list of pointers to objects in that area
+			for (const auto& object : treeObjects.search(rScreen))
+			{
+				tv.FillRectDecal(object->vPos, object->vSize, object->colour);
+				nObjectCount++;
+			}
+			std::chrono::duration<float> duration = std::chrono::system_clock::now() - tpStart;
+
+
+			std::string sOutput = "Quadtree " + std::to_string(nObjectCount) + "/" + std::to_string(vecObjects.size()) + " in " + std::to_string(duration.count());
+			DrawStringDecal({ 4, 4 }, sOutput, olc::BLACK, { 4.0f, 8.0f });
+			DrawStringDecal({ 2, 2 }, sOutput, olc::WHITE, { 4.0f, 8.0f });
+
+		}
+		else
+		{
+			// LINEAR SEARCH MODE
+			auto tpStart = std::chrono::system_clock::now();
+
+			// Blindly check all objects to see if they overlap with screen
+			for (const auto& object : vecObjects)
+			{
+				if (rScreen.overlaps({ object.vPos, object.vSize }))
+				{
+					tv.FillRectDecal(object.vPos, object.vSize, object.colour);
+					nObjectCount++;
+				}
+			}
+			std::chrono::duration<float> duration = std::chrono::system_clock::now() - tpStart;
+
+			std::string sOutput = "Linear " + std::to_string(nObjectCount) + "/" + std::to_string(vecObjects.size()) + " in " + std::to_string(duration.count());
+			DrawStringDecal({ 4, 4 }, sOutput, olc::BLACK, { 4.0f, 8.0f });
+			DrawStringDecal({ 2, 2 }, sOutput, olc::WHITE, { 4.0f, 8.0f });
+		}
+
+		return true;
+	}
+};
+
+
+int main()
+{
+	Example_StaticQuadTree demo;
+	if (demo.Construct(1280, 960, 1, 1, false, false))
+		demo.Start();
+	return 0;
+}