SDL2系列教程6-纹理测试例程

#include <iostream> #include <SDL2/SDL.h> #include <cmath> using namespace std; bool init(); void kill(); bool loop(); // Pointers to our window, renderer, and texture SDL_Window* window; SDL_Renderer* renderer; SDL_Texture* texture; int main(int argc, char** args) { if ( !init() ) return 1; while ( loop() ) { // wait before processing the next frame SDL_Delay(10); } kill(); return 0; } bool loop() { static const unsigned char* keys = SDL_GetKeyboardState( NULL ); SDL_Event e; SDL_Rect dest; static int mx = -1, my = -1; static double rot = 0; // Clear the window to white SDL_SetRenderDrawColor( renderer, 255, 255, 255, 255 ); SDL_RenderClear( renderer ); // Event loop while ( SDL_PollEvent( &e ) != 0 ) { switch ( e.type ) { case SDL_QUIT: return false; case SDL_MOUSEMOTION: mx = e.motion.x; my = e.motion.y; break; } } if ( mx != -1 ) { // Distance across window float wpercent = mx / 640.0f; float hpercent = my / 480.0f; // Color unsigned char r = round( wpercent * 255 ); unsigned char g = round( hpercent * 255 ); // Color mod (b will always be zero) SDL_SetTextureColorMod( texture, r, g, 0 ); mx -= 320; my -= 240; rot = atan((float)my / (float)mx) * (180.0f / 3.14f); if (mx < 0) rot -= 180; } mx = my = -1; // Render texture dest.x = 240; dest.y = 180; dest.w = 160; dest.h = 120; SDL_RenderCopyEx(renderer, texture, NULL, &dest, rot, NULL, keys[SDL_SCANCODE_F] ? SDL_FLIP_VERTICAL : SDL_FLIP_NONE); // Update window SDL_RenderPresent( renderer ); return true; } bool init() { if ( SDL_Init( SDL_INIT_EVERYTHING ) < 0 ) { cout << "Error initializing SDL: " << SDL_GetError() << endl; return false; } window = SDL_CreateWindow( "Example", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 640, 480, SDL_WINDOW_SHOWN ); if ( !window ) { cout << "Error creating window: " << SDL_GetError() << endl; return false; } renderer = SDL_CreateRenderer( window, -1, SDL_RENDERER_ACCELERATED ); if ( !renderer ) { cout << "Error creating renderer: " << SDL_GetError() << endl; return false; } // Load bitmap into surface SDL_Surface* buffer = SDL_LoadBMP("test.bmp"); if ( !buffer ) { cout << "Error loading image test.bmp: " << SDL_GetError() << endl; return false; } // Create texture texture = SDL_CreateTextureFromSurface( renderer, buffer ); // Free surface as it's no longer needed SDL_FreeSurface( buffer ); buffer = NULL; if ( !texture ) { cout << "Error creating texture: " << SDL_GetError() << endl; return false; } return true; } void kill() { SDL_DestroyTexture( texture ); SDL_DestroyRenderer( renderer ); SDL_DestroyWindow( window ); texture = NULL; window = NULL; renderer = NULL; SDL_Quit(); }