(C++) SDL example 3: moving a sprite over a background

 

This SDL example shows a sprite moving a over a background, like this screenshot (png).

 

Operating system: Ubuntu

IDE: Qt Creator 2.0.0

Project type: Qt4 Console Application

Selected required modules: QtCore

Compiler: G++ 4.4.1

Additional libraries: SDL

 

 

 

 

 

Qt project file

 

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#------------------------------------------------- # # Project created by QtCreator 2010-07-17T14:57:33 # #------------------------------------------------- QT += core QT -= gui TARGET = CppSdlExample3 CONFIG += console CONFIG -= app_bundle TEMPLATE = app LIBS += -L/usr/local/lib -lSDL SOURCES += main.cpp

 

 

 

 

 

Source code

 

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#include <cassert> #include <cstdlib> #include <SDL/SDL.h> int main() {   //Start SDL   if (SDL_Init( SDL_INIT_EVERYTHING ) < 0)   {     assert(!"Should not get here. Initialization failed");   }   //Call SDL_Quit upon exit   std::atexit(SDL_Quit);   //Load background   SDL_Surface * const background = SDL_LoadBMP( "Background.bmp");   assert(background && "Assume background image is found in same folder as binary");   assert(background->w > 100);   assert(background->h > 100);   //Set up screen, same size as background   SDL_Surface * const screen = SDL_SetVideoMode(background->w,background->h, 32, SDL_SWSURFACE );   assert(screen && "Assume screen can be initialized");   //Load sprite   SDL_Surface * const sprite = SDL_LoadBMP("Butterfly.bmp");   SDL_SetColorKey(sprite, SDL_SRCCOLORKEY | SDL_RLEACCEL,SDL_MapRGB(sprite->format,0,255,0));   assert(sprite && "Assume sprite image is found in same folder as binary");   //Create a sprite rect, same dimensions as sprite image   SDL_Rect sprite_rect;   sprite_rect.x = 0;   sprite_rect.y = 0;   sprite_rect.h = sprite->h;   sprite_rect.w = sprite->w;   int dx = 1; //Horizontal speed   int dy = 1; //Vertical speed   //Blit background to screen   SDL_BlitSurface( background, 0, screen, 0);   while (1)   {     //Remove-blit image from screen     SDL_BlitSurface( background, &sprite_rect, screen, &sprite_rect);     //Move sprite     sprite_rect.x+=dx;     sprite_rect.y+=dy;     //Make sprite bounce     if (sprite_rect.x < 0) dx=-dx;     if (sprite_rect.x + sprite_rect.w > screen->w) dx=-dx;     if (sprite_rect.y < 0) dy=-dy;     if (sprite_rect.y + sprite_rect.h > screen->h) dy=-dy;     //Blit image to screen     SDL_BlitSurface( sprite, 0, screen, &sprite_rect);     //Update screen     SDL_Flip( screen );     //Wait for user to close window     SDL_Event event;     SDL_PollEvent(&event);     if (event.type == SDL_QUIT) break;   }   //Free the loaded image   SDL_FreeSurface( background ); }