[SDL] My sprite doesn't move.

[kake_fisk]

Hi, i'm quite new to SDL, but i have some problems moving the sprite on keypress.
Here's my code:

#ifdef __cplusplus
    #include <cstdlib>
#else
    #include <stdlib.h>
#endif
#ifdef __APPLE__
#include <SDL/SDL.h>
#else
#include <SDL.h>
#endif

int main ( int argc, char** argv )
{
    // initialize SDL video
    if ( SDL_Init( SDL_INIT_VIDEO ) < 0 )
    {
        printf( "Unable to init SDL: %s\n", SDL_GetError() );
        return 1;
    }

    // make sure SDL cleans up before exit
    atexit(SDL_Quit);

    // create a new window
    SDL_Surface* screen = SDL_SetVideoMode(640, 480, 16,
                                           SDL_HWSURFACE|SDL_DOUBLEBUF);
    if ( !screen )
    {
        printf("Unable to set 640x480 video: %s\n", SDL_GetError());
        return 1;
    }

    // load an image
    SDL_Surface* bmp = SDL_LoadBMP("cb.bmp");
    if (!bmp)
    {
        printf("Unable to load bitmap: %s\n", SDL_GetError());
        return 1;
    }

    // centre the bitmap on screen
    int spr1_x = 0, spr1_y = 0;
    SDL_Rect dstrect;
    dstrect.x = spr1_x;
    dstrect.y = spr1_y;

    // program main loop
    bool up = false;
    bool down = false;
    bool left = false;
    bool right = false;
    bool done = false;
    while (!done)
    {
        // message processing loop
        SDL_Event event;
        while (SDL_PollEvent(&event))
        {
            // check for messages
            switch (event.type)
            {
                // exit if the window is closed
            case SDL_QUIT:
                done = true;
                break;

            case SDL_KEYDOWN:
                {
                    switch (event.key.keysym.sym)
                    {
                        case SDLK_LEFT:
                        left = true;
                        break;
                        case SDLK_RIGHT:
                        right = true;
                        break;
                        case SDLK_UP:
                        up = true;
                        break;
                        case SDLK_DOWN:
                        down = true;
                        break;
                        case SDLK_ESCAPE:
                        done = true;
                        break;
                        default:
                        break;
                    }
                }

                case SDL_KEYUP:
                switch( event.key.keysym.sym )
                {
                    case SDLK_LEFT:
                        left = false;
                        break;
                        case SDLK_RIGHT:
                        left = false;
                        break;
                        case SDLK_UP:
                        left = false;
                        break;
                        case SDLK_DOWN:
                        left = false;
                        break;
                        default:
                        break;
                }
            } // end switch
        } // end of message processing

if (left)
{spr1_x -= 1;}
if (right)
{spr1_x += 1;}
if (up)
{spr1_y -= 1;}
if (down)
{spr1_y += 1;}

        // DRAWING STARTS HERE

        // clear screen
        SDL_FillRect(screen, 0, SDL_MapRGB(screen->format, 0, 0, 0));

        // draw bitmap
        SDL_BlitSurface(bmp, 0, screen, &dstrect);

        // DRAWING ENDS HERE

        // finally, update the screen :)
        SDL_Flip(screen);
    } // end main loop

    // free loaded bitmap
    SDL_FreeSurface(bmp);

    // all is well ;)
    printf("Exited cleanly\n");
    return 0;
}

Do anybody know whats wrong?

[salehhamadeh]

Instead of adding the spr1_x and spr1_y by 1, you should write dstrect.x +=1 and dstrect.y += 1