Introduction to 2D Linux Game Programming/Algorithms/Simple Software Transformations/90° Image Rotation

90° Image Rotation In 2D games it's often necessary to rotate an image by 90 degrees. This algorithm does so quickly and easily. The Source: // Rotate90.cpp #include <iostream> #include "include/S.h" #include <string> #include <sstream> using namespace std; int main() { // All rotations are clockwise // rotate = 0 - do nothing // rotate = 1 - rotate 90 // rotate = 2 - rotate 180 // rotate = 3 - rotate 270 // const int rotate; const int width = S::sw(); // The original Array's width cout << "\n"; const int height = S::sh(width); // The original Array's height const int widthheight = width * height; int source[widthheight]; int dest[widthheight]; int rotate; for(int x = 0; x < widthheight; x++) source[x]=x; cout << "\n\n"; S::print_rect(width, height, &source[0]); cout << "\nTo rotate clockwise by 0 degrees enter 0." << "\nTo rotate clockwise by 90 degrees enter 1." << "\nTo rotate clockwise by 180 degrees enter 2." << "\nTo rotate clockwise by 270 degrees enter 3: "; cin >> rotate; cout << "\n\n"; switch(rotate) { // Do nothing case 0: S::print_rect(width, height, &source[0]); break; // Rotate 90 case 1: for(int h = 0, dest_col = height - 1; h < height; ++h, --dest_col) { for(int w = 0; w < width; w++) { dest[ ( w * height ) + dest_col] = source[h*width + w]; } } S::print_rect(height, width, &dest[0]); break; // Rotate 180 case 2: for( int h=0, dest_row=(height-1); h < height; --dest_row, ++h ) { for ( int w=0, dest_col=(width-1); w < width; ++w, --dest_col ) { dest[ dest_row * width + dest_col] = source[h*width + w]; } } S::print_rect(width, height, &dest[0]); break; // Rotate 270 case 3: for(int h = 0, dest_col=0; h < height; ++dest_col, ++h) { for(int w=0, dest_row=width-1; w < width; --dest_row, ++w) { dest[(dest_row * height) + dest_col] = source[ h * width + w]; } } S::print_rect(height, width, &dest[0]); break; // Out of range, do nothing default: break; } cout << endl; return 0; }