Added RayCastDDA Video

Videos/OneLoneCoder_PGE_RayCastDDA.cpp

@@ -0,0 +1,215 @@
+/*
+	Fast Ray Casting Using DDA
+	"Itchy Eyes... Not blinking enough..." - javidx9
+
+	Video: https://youtu.be/NbSee-XM7WA
+
+	License (OLC-3)
+	~~~~~~~~~~~~~~~
+
+	Copyright 2018 - 2021 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.
+
+	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
+*/
+
+#define OLC_PGE_APPLICATION
+#include "olcPixelGameEngine.h"
+
+class Example : public olc::PixelGameEngine
+{
+public:
+	Example()
+	{
+		sAppName = "RayCast With DDA Algorithm";
+	}
+
+	olc::vf2d vPlayer = { 0,0 };
+	olc::vi2d vMapSize = { 32, 30 };
+	olc::vi2d vCellSize = { 16, 16 };
+	std::vector<int> vecMap;
+
+
+public:
+	bool OnUserCreate() override
+	{
+		// Construct Map
+		vecMap.resize(vMapSize.x * vMapSize.y);
+		return true;
+	}
+
+	bool OnUserUpdate(float fElapsedTime) override
+	{
+		olc::vf2d vMouse = { float(GetMouseX()), float(GetMouseY()) };
+		olc::vf2d vMouseCell = vMouse / vCellSize;
+		olc::vi2d vCell = vMouseCell; // implicit cast to integer, rounds down
+
+		// Paint with right mouse button "solid" tiles
+		if (GetMouse(1).bHeld) vecMap[vCell.y * vMapSize.x + vCell.x] = 1;
+
+		// Move "player" position
+		if (GetKey(olc::Key::W).bHeld) vPlayer.y -= 25.0f * fElapsedTime;
+		if (GetKey(olc::Key::S).bHeld) vPlayer.y += 25.0f * fElapsedTime;
+		if (GetKey(olc::Key::A).bHeld) vPlayer.x -= 25.0f * fElapsedTime;
+		if (GetKey(olc::Key::D).bHeld) vPlayer.x += 25.0f * fElapsedTime;
+
+		// DDA Algorithm ==============================================
+		// https://lodev.org/cgtutor/raycasting.html
+
+
+		// Form ray cast from player into scene
+		olc::vf2d vRayStart = vPlayer;
+		olc::vf2d vRayDir = (vMouseCell - vPlayer).norm();
+				
+		// Lodev.org also explains this additional optimistaion (but it's beyond scope of video)
+		// olc::vf2d vRayUnitStepSize = { abs(1.0f / vRayDir.x), abs(1.0f / vRayDir.y) };
+
+		olc::vf2d vRayUnitStepSize = { sqrt(1 + (vRayDir.y / vRayDir.x) * (vRayDir.y / vRayDir.x)), sqrt(1 + (vRayDir.x / vRayDir.y) * (vRayDir.x / vRayDir.y)) };
+		olc::vi2d vMapCheck = vRayStart;
+		olc::vf2d vRayLength1D;
+		olc::vi2d vStep;
+
+		// Establish Starting Conditions
+		if (vRayDir.x < 0)
+		{
+			vStep.x = -1;
+			vRayLength1D.x = (vRayStart.x - float(vMapCheck.x)) * vRayUnitStepSize.x;
+		}
+		else
+		{
+			vStep.x = 1;
+			vRayLength1D.x = (float(vMapCheck.x + 1) - vRayStart.x) * vRayUnitStepSize.x;
+		}
+
+		if (vRayDir.y < 0)
+		{
+			vStep.y = -1;
+			vRayLength1D.y = (vRayStart.y - float(vMapCheck.y)) * vRayUnitStepSize.y;
+		}
+		else
+		{
+			vStep.y = 1;
+			vRayLength1D.y = (float(vMapCheck.y + 1) - vRayStart.y) * vRayUnitStepSize.y;
+		}
+
+		// Perform "Walk" until collision or range check
+		bool bTileFound = false;
+		float fMaxDistance = 100.0f;
+		float fDistance = 0.0f;
+		while (!bTileFound && fDistance < fMaxDistance)
+		{
+			// Walk along shortest path
+			if (vRayLength1D.x < vRayLength1D.y)
+			{
+				vMapCheck.x += vStep.x;
+				fDistance = vRayLength1D.x;
+				vRayLength1D.x += vRayUnitStepSize.x;
+			}
+			else
+			{
+				vMapCheck.y += vStep.y;
+				fDistance = vRayLength1D.y;
+				vRayLength1D.y += vRayUnitStepSize.y;
+			}
+
+			// Test tile at new test point
+			if (vMapCheck.x >= 0 && vMapCheck.x < vMapSize.x && vMapCheck.y >= 0 && vMapCheck.y < vMapSize.y)
+			{
+				if (vecMap[vMapCheck.y * vMapSize.x + vMapCheck.x] == 1)
+				{
+					bTileFound = true;
+				}
+			}
+		}
+
+		// Calculate intersection location
+		olc::vf2d vIntersection;
+		if (bTileFound)
+		{
+			vIntersection = vRayStart + vRayDir * fDistance;
+		}
+
+
+
+		Clear(olc::BLACK);
+
+		// Draw Map
+		for (int y = 0; y < vMapSize.y; y++)
+		{
+			for (int x = 0; x < vMapSize.x; x++)
+			{
+				int cell = vecMap[y * vMapSize.x + x];
+				if (cell == 1)
+					FillRect(olc::vi2d(x, y) * vCellSize, vCellSize, olc::BLUE);
+
+				// Draw Cell border
+				DrawRect(olc::vi2d(x, y) * vCellSize, vCellSize, olc::DARK_GREY);
+			}
+		}
+
+		// Draw ray between player and mouse if left mouse button held
+		if (GetMouse(0).bHeld)
+		{
+			DrawLine(vPlayer * vCellSize, vMouse, olc::WHITE, 0xF0F0F0F0);
+
+			if (bTileFound)
+			{
+				DrawCircle(vIntersection * vCellSize, 4.0f, olc::YELLOW);
+			}
+		}
+
+		// Draw Player
+		FillCircle(vPlayer * vCellSize, 4.0f, olc::RED);
+
+		// Draw Mouse
+		FillCircle(vMouse, 4.0f, olc::GREEN);
+		return true;
+	}
+};
+
+int main()
+{
+	Example demo;
+	if (demo.Construct(512, 480, 2, 2))
+		demo.Start();
+	return 0;
+}