Added Sprite Transforms video

OneLoneCoder_PGE_SpriteTransforms.cpp

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+/*
+	OneLoneCoder.com - 2D Sprite Affine Transformations
+	"No more 90 degree movements" - @Javidx9
+
+
+	Background
+	~~~~~~~~~~
+	The sophistication of 2D engines is enhanced when the programmer is
+	able to rotate and scale sprites in a convenient manner. This program
+	shows the basics of how affine transformations accomplish this.
+
+	License (OLC-3)
+	~~~~~~~~~~~~~~~
+
+	Copyright 2018 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
+	Discord:	https://discord.gg/WhwHUMV
+	Twitter:	https://www.twitter.com/javidx9
+	Twitch:		https://www.twitch.tv/javidx9
+	GitHub:		https://www.github.com/onelonecoder
+	Patreon:	https://www.patreon.com/javidx9
+	Homepage:	https://www.onelonecoder.com
+
+	Relevant Videos
+	~~~~~~~~~~~~~~~
+	https://youtu.be/zxwLN2blwbQ
+
+	Author
+	~~~~~~
+	David Barr, aka javidx9, ©OneLoneCoder 2018
+*/
+
+
+#define OLC_PGE_APPLICATION
+#include "olcPixelGameEngine.h"
+
+#include <algorithm>
+#undef min
+#undef max
+
+
+class SpriteTransforms : public olc::PixelGameEngine
+{
+public:
+	SpriteTransforms()
+	{
+		sAppName = "Sprite Transforms";
+	}
+
+private:
+	olc::Sprite *sprCar;
+
+	struct matrix3x3
+	{
+		float m[3][3];
+	};
+
+	void Identity(matrix3x3 &mat)
+	{
+		mat.m[0][0] = 1.0f; mat.m[1][0] = 0.0f; mat.m[2][0] = 0.0f;
+		mat.m[0][1] = 0.0f; mat.m[1][1] = 1.0f; mat.m[2][1] = 0.0f;
+		mat.m[0][2] = 0.0f; mat.m[1][2] = 0.0f; mat.m[2][2] = 1.0f;
+	}
+
+	void Translate(matrix3x3 &mat, float ox, float oy)
+	{
+		mat.m[0][0] = 1.0f; mat.m[1][0] = 0.0f; mat.m[2][0] = ox;
+		mat.m[0][1] = 0.0f; mat.m[1][1] = 1.0f; mat.m[2][1] = oy;
+		mat.m[0][2] = 0.0f;	mat.m[1][2] = 0.0f;	mat.m[2][2] = 1.0f;
+	}
+
+	void Rotate(matrix3x3 &mat, float fTheta)
+	{
+		mat.m[0][0] = cosf(fTheta);  mat.m[1][0] = sinf(fTheta); mat.m[2][0] = 0.0f;
+		mat.m[0][1] = -sinf(fTheta); mat.m[1][1] = cosf(fTheta); mat.m[2][1] = 0.0f;
+		mat.m[0][2] = 0.0f;			 mat.m[1][2] = 0.0f;		 mat.m[2][2] = 1.0f;
+	}
+
+	void Scale(matrix3x3 &mat, float sx, float sy)
+	{
+		mat.m[0][0] = sx;   mat.m[1][0] = 0.0f; mat.m[2][0] = 0.0f;
+		mat.m[0][1] = 0.0f; mat.m[1][1] = sy;   mat.m[2][1] = 0.0f;
+		mat.m[0][2] = 0.0f;	mat.m[1][2] = 0.0f;	mat.m[2][2] = 1.0f;
+	}
+
+	void Shear(matrix3x3 &mat, float sx, float sy)
+	{	
+		mat.m[0][0] = 1.0f; mat.m[1][0] = sx;   mat.m[2][0] = 0.0f;
+		mat.m[0][1] = sy;   mat.m[1][1] = 1.0f; mat.m[2][1] = 0.0f;
+		mat.m[0][2] = 0.0f;	mat.m[1][2] = 0.0f;	mat.m[2][2] = 1.0f;
+	}
+
+	void MatrixMultiply(matrix3x3 &matResult, matrix3x3 &matA, matrix3x3 &matB)
+	{
+		for (int c = 0; c < 3; c++)
+		{
+			for (int r = 0; r < 3; r++)
+			{
+				matResult.m[c][r] = matA.m[0][r] * matB.m[c][0] +
+					                matA.m[1][r] * matB.m[c][1] +
+					                matA.m[2][r] * matB.m[c][2];
+			}
+		}
+	}
+
+	void Forward(matrix3x3 &mat, float in_x, float in_y, float &out_x, float &out_y)
+	{
+		out_x = in_x * mat.m[0][0] + in_y * mat.m[1][0] + mat.m[2][0];
+		out_y = in_x * mat.m[0][1] + in_y * mat.m[1][1] + mat.m[2][1];
+	}
+
+	void Invert(matrix3x3 &matIn, matrix3x3 &matOut)
+	{
+		float det = matIn.m[0][0] * (matIn.m[1][1] * matIn.m[2][2] - matIn.m[1][2] * matIn.m[2][1]) -
+			matIn.m[1][0] * (matIn.m[0][1] * matIn.m[2][2] - matIn.m[2][1] * matIn.m[0][2]) +
+			matIn.m[2][0] * (matIn.m[0][1] * matIn.m[1][2] - matIn.m[1][1] * matIn.m[0][2]);
+
+		float idet = 1.0f / det;
+		matOut.m[0][0] = (matIn.m[1][1] * matIn.m[2][2] - matIn.m[1][2] * matIn.m[2][1]) * idet;
+		matOut.m[1][0] = (matIn.m[2][0] * matIn.m[1][2] - matIn.m[1][0] * matIn.m[2][2]) * idet;
+		matOut.m[2][0] = (matIn.m[1][0] * matIn.m[2][1] - matIn.m[2][0] * matIn.m[1][1]) * idet;
+		matOut.m[0][1] = (matIn.m[2][1] * matIn.m[0][2] - matIn.m[0][1] * matIn.m[2][2]) * idet;
+		matOut.m[1][1] = (matIn.m[0][0] * matIn.m[2][2] - matIn.m[2][0] * matIn.m[0][2]) * idet;
+		matOut.m[2][1] = (matIn.m[0][1] * matIn.m[2][0] - matIn.m[0][0] * matIn.m[2][1]) * idet;
+		matOut.m[0][2] = (matIn.m[0][1] * matIn.m[1][2] - matIn.m[0][2] * matIn.m[1][1]) * idet;
+		matOut.m[1][2] = (matIn.m[0][2] * matIn.m[1][0] - matIn.m[0][0] * matIn.m[1][2]) * idet;
+		matOut.m[2][2] = (matIn.m[0][0] * matIn.m[1][1] - matIn.m[0][1] * matIn.m[1][0]) * idet;
+	}
+
+
+	float fRotate = 0.0f;
+
+public:
+	bool OnUserCreate() override
+	{
+		sprCar = new olc::Sprite("car_top1.png");
+
+		return true;
+	}
+
+	bool OnUserUpdate(float fElapsedTime) override
+	{
+		
+		if (GetKey(olc::Key::Z).bHeld) fRotate -= 2.0f * fElapsedTime;
+		if (GetKey(olc::Key::X).bHeld) fRotate += 2.0f * fElapsedTime;
+		
+		
+		Clear(olc::DARK_CYAN);
+
+		SetPixelMode(olc::Pixel::ALPHA);
+		//DrawSprite(0, 0, sprCar, 3);
+		
+
+		matrix3x3 matFinal, matA, matB, matC, matFinalInv;
+		Translate(matA, -100, -50);
+		Rotate(matB, fRotate);
+		MatrixMultiply(matC, matB, matA);
+
+		Translate(matA, (float)ScreenWidth()/2, (float)ScreenHeight()/2);
+		MatrixMultiply(matFinal, matA, matC);
+
+		Invert(matFinal, matFinalInv);
+
+		// Draws the dumb way, but leaves gaps
+		/*for (int x = 0; x < sprCar->width; x++)
+		{
+			for (int y = 0; y < sprCar->height; y++)
+			{
+				olc::Pixel p = sprCar->GetPixel(x, y);
+
+				float nx, ny;
+				Forward(matFinal, (float)x, (float)y, nx, ny);
+				Draw(nx, ny, p);
+			}
+		}*/
+
+		// Work out bounding box of sprite post-transformation
+		// by passing through sprite corner locations into 
+		// transformation matrix
+		float ex, ey;
+		float sx, sy;
+		float px, py;
+
+		Forward(matFinal, 0.0f, 0.0f, px, py);
+		sx = px; sy = py;
+		ex = px; ey = py;
+
+		Forward(matFinal, (float)sprCar->width, (float)sprCar->height, px, py);
+		sx = std::min(sx, px); sy = std::min(sy, py);
+		ex = std::max(ex, px); ey = std::max(ey, py);
+
+		Forward(matFinal, 0.0f, (float)sprCar->height, px, py);
+		sx = std::min(sx, px); sy = std::min(sy, py);
+		ex = std::max(ex, px); ey = std::max(ey, py);
+
+		Forward(matFinal, (float)sprCar->width, 0.0f, px, py);
+		sx = std::min(sx, px); sy = std::min(sy, py);
+		ex = std::max(ex, px); ey = std::max(ey, py);
+
+		// Use transformed corner locations in screen space to establish
+		// region of pixels to fill, using inverse transform to sample
+		// sprite at suitable locations.
+		for (int x = sx; x < ex; x++)
+		{
+			for (int y = sy; y < ey; y++)
+			{
+				float nx, ny;
+				Forward(matFinalInv, (float)x, (float)y, nx, ny);
+				olc::Pixel p = sprCar->GetPixel((int32_t)(nx + 0.5f), (int32_t)(ny + 0.5f));
+				Draw(x, y, p);
+			}
+		}
+
+		SetPixelMode(olc::Pixel::NORMAL);
+
+		return true;
+	}
+};
+
+int main()
+{
+	SpriteTransforms demo;
+	if (demo.Construct(256, 240, 4, 4))
+		demo.Start();
+	return 0;
+}