Javidx9
6 years ago
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/*
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OneLoneCoder.com - 2D Sprite Affine Transformations |
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"No more 90 degree movements" - @Javidx9 |
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Background |
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~~~~~~~~~~ |
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The sophistication of 2D engines is enhanced when the programmer is |
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able to rotate and scale sprites in a convenient manner. This program |
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shows the basics of how affine transformations accomplish this. |
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License (OLC-3) |
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~~~~~~~~~~~~~~~ |
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Copyright 2018 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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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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Links |
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~~~~~ |
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YouTube: https://www.youtube.com/javidx9
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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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Patreon: https://www.patreon.com/javidx9
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Homepage: https://www.onelonecoder.com
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Relevant Videos |
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~~~~~~~~~~~~~~~ |
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https://youtu.be/zxwLN2blwbQ
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Author |
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~~~~~~ |
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David Barr, aka javidx9, ©OneLoneCoder 2018 |
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*/ |
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#define OLC_PGE_APPLICATION |
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#include "olcPixelGameEngine.h" |
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#include <algorithm> |
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#undef min |
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#undef max |
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class SpriteTransforms : public olc::PixelGameEngine |
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{ |
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public: |
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SpriteTransforms() |
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{ |
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sAppName = "Sprite Transforms"; |
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} |
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private: |
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olc::Sprite *sprCar; |
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struct matrix3x3 |
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{ |
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float m[3][3]; |
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}; |
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void Identity(matrix3x3 &mat) |
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{ |
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mat.m[0][0] = 1.0f; mat.m[1][0] = 0.0f; mat.m[2][0] = 0.0f; |
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mat.m[0][1] = 0.0f; mat.m[1][1] = 1.0f; mat.m[2][1] = 0.0f; |
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mat.m[0][2] = 0.0f; mat.m[1][2] = 0.0f; mat.m[2][2] = 1.0f; |
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} |
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void Translate(matrix3x3 &mat, float ox, float oy) |
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{ |
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mat.m[0][0] = 1.0f; mat.m[1][0] = 0.0f; mat.m[2][0] = ox; |
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mat.m[0][1] = 0.0f; mat.m[1][1] = 1.0f; mat.m[2][1] = oy; |
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mat.m[0][2] = 0.0f; mat.m[1][2] = 0.0f; mat.m[2][2] = 1.0f; |
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} |
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void Rotate(matrix3x3 &mat, float fTheta) |
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{ |
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mat.m[0][0] = cosf(fTheta); mat.m[1][0] = sinf(fTheta); mat.m[2][0] = 0.0f; |
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mat.m[0][1] = -sinf(fTheta); mat.m[1][1] = cosf(fTheta); mat.m[2][1] = 0.0f; |
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mat.m[0][2] = 0.0f; mat.m[1][2] = 0.0f; mat.m[2][2] = 1.0f; |
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} |
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void Scale(matrix3x3 &mat, float sx, float sy) |
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{ |
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mat.m[0][0] = sx; mat.m[1][0] = 0.0f; mat.m[2][0] = 0.0f; |
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mat.m[0][1] = 0.0f; mat.m[1][1] = sy; mat.m[2][1] = 0.0f; |
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mat.m[0][2] = 0.0f; mat.m[1][2] = 0.0f; mat.m[2][2] = 1.0f; |
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} |
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void Shear(matrix3x3 &mat, float sx, float sy) |
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{
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mat.m[0][0] = 1.0f; mat.m[1][0] = sx; mat.m[2][0] = 0.0f; |
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mat.m[0][1] = sy; mat.m[1][1] = 1.0f; mat.m[2][1] = 0.0f; |
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mat.m[0][2] = 0.0f; mat.m[1][2] = 0.0f; mat.m[2][2] = 1.0f; |
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} |
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void MatrixMultiply(matrix3x3 &matResult, matrix3x3 &matA, matrix3x3 &matB) |
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{ |
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for (int c = 0; c < 3; c++) |
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{ |
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for (int r = 0; r < 3; r++) |
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{ |
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matResult.m[c][r] = matA.m[0][r] * matB.m[c][0] + |
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matA.m[1][r] * matB.m[c][1] + |
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matA.m[2][r] * matB.m[c][2]; |
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} |
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} |
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} |
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void Forward(matrix3x3 &mat, float in_x, float in_y, float &out_x, float &out_y) |
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{ |
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out_x = in_x * mat.m[0][0] + in_y * mat.m[1][0] + mat.m[2][0]; |
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out_y = in_x * mat.m[0][1] + in_y * mat.m[1][1] + mat.m[2][1]; |
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} |
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void Invert(matrix3x3 &matIn, matrix3x3 &matOut) |
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{ |
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float det = matIn.m[0][0] * (matIn.m[1][1] * matIn.m[2][2] - matIn.m[1][2] * matIn.m[2][1]) - |
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matIn.m[1][0] * (matIn.m[0][1] * matIn.m[2][2] - matIn.m[2][1] * matIn.m[0][2]) + |
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matIn.m[2][0] * (matIn.m[0][1] * matIn.m[1][2] - matIn.m[1][1] * matIn.m[0][2]); |
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float idet = 1.0f / det; |
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matOut.m[0][0] = (matIn.m[1][1] * matIn.m[2][2] - matIn.m[1][2] * matIn.m[2][1]) * idet; |
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matOut.m[1][0] = (matIn.m[2][0] * matIn.m[1][2] - matIn.m[1][0] * matIn.m[2][2]) * idet; |
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matOut.m[2][0] = (matIn.m[1][0] * matIn.m[2][1] - matIn.m[2][0] * matIn.m[1][1]) * idet; |
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matOut.m[0][1] = (matIn.m[2][1] * matIn.m[0][2] - matIn.m[0][1] * matIn.m[2][2]) * idet; |
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matOut.m[1][1] = (matIn.m[0][0] * matIn.m[2][2] - matIn.m[2][0] * matIn.m[0][2]) * idet; |
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matOut.m[2][1] = (matIn.m[0][1] * matIn.m[2][0] - matIn.m[0][0] * matIn.m[2][1]) * idet; |
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matOut.m[0][2] = (matIn.m[0][1] * matIn.m[1][2] - matIn.m[0][2] * matIn.m[1][1]) * idet; |
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matOut.m[1][2] = (matIn.m[0][2] * matIn.m[1][0] - matIn.m[0][0] * matIn.m[1][2]) * idet; |
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matOut.m[2][2] = (matIn.m[0][0] * matIn.m[1][1] - matIn.m[0][1] * matIn.m[1][0]) * idet; |
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} |
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float fRotate = 0.0f; |
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public: |
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bool OnUserCreate() override |
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{ |
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sprCar = new olc::Sprite("car_top1.png"); |
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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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if (GetKey(olc::Key::Z).bHeld) fRotate -= 2.0f * fElapsedTime; |
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if (GetKey(olc::Key::X).bHeld) fRotate += 2.0f * fElapsedTime; |
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Clear(olc::DARK_CYAN); |
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SetPixelMode(olc::Pixel::ALPHA); |
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//DrawSprite(0, 0, sprCar, 3);
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matrix3x3 matFinal, matA, matB, matC, matFinalInv; |
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Translate(matA, -100, -50); |
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Rotate(matB, fRotate); |
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MatrixMultiply(matC, matB, matA); |
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Translate(matA, (float)ScreenWidth()/2, (float)ScreenHeight()/2); |
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MatrixMultiply(matFinal, matA, matC); |
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Invert(matFinal, matFinalInv); |
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// Draws the dumb way, but leaves gaps
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/*for (int x = 0; x < sprCar->width; x++)
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{ |
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for (int y = 0; y < sprCar->height; y++) |
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{ |
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olc::Pixel p = sprCar->GetPixel(x, y); |
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float nx, ny; |
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Forward(matFinal, (float)x, (float)y, nx, ny); |
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Draw(nx, ny, p); |
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} |
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}*/ |
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// Work out bounding box of sprite post-transformation
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// by passing through sprite corner locations into
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// transformation matrix
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float ex, ey; |
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float sx, sy; |
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float px, py; |
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Forward(matFinal, 0.0f, 0.0f, px, py); |
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sx = px; sy = py; |
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ex = px; ey = py; |
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Forward(matFinal, (float)sprCar->width, (float)sprCar->height, px, py); |
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sx = std::min(sx, px); sy = std::min(sy, py); |
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ex = std::max(ex, px); ey = std::max(ey, py); |
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Forward(matFinal, 0.0f, (float)sprCar->height, px, py); |
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sx = std::min(sx, px); sy = std::min(sy, py); |
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ex = std::max(ex, px); ey = std::max(ey, py); |
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Forward(matFinal, (float)sprCar->width, 0.0f, px, py); |
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sx = std::min(sx, px); sy = std::min(sy, py); |
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ex = std::max(ex, px); ey = std::max(ey, py); |
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// Use transformed corner locations in screen space to establish
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// region of pixels to fill, using inverse transform to sample
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// sprite at suitable locations.
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for (int x = sx; x < ex; x++) |
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{ |
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for (int y = sy; y < ey; y++) |
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{ |
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float nx, ny; |
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Forward(matFinalInv, (float)x, (float)y, nx, ny); |
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olc::Pixel p = sprCar->GetPixel((int32_t)(nx + 0.5f), (int32_t)(ny + 0.5f)); |
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Draw(x, y, p); |
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} |
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} |
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SetPixelMode(olc::Pixel::NORMAL); |
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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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SpriteTransforms demo; |
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if (demo.Construct(256, 240, 4, 4)) |
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demo.Start(); |
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return 0; |
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} |
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After Width: | Height: | Size: 16 KiB |
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