SDL tutorial 16

//http://www.youtube.com/user/thecplusplusguy
//Thanks for the typed in code to Tapit85
//you need background.bmp (2000 x 480), tree_key.bmp
#include <SDL/SDL.h>
#include <iostream>

bool collision(SDL_Rect* rect1,SDL_Rect* rect2)
{
    if(rect1->y >= rect2->y + rect2->h)
        return 0;
    if(rect1->x >= rect2->x + rect2->w)
        return 0;
    if(rect1->y + rect1->h <= rect2->y)
        return 0;
    if(rect1->x + rect1->w <= rect2->x)
        return 0;
    return 1;
}

int width = 640;
int height = 480;

int main(int argc, char** argv)
{
    SDL_Init(SDL_INIT_EVERYTHING);
    SDL_Surface *screen, *background, *image;
    screen = SDL_SetVideoMode(width, height, 32, SDL_SWSURFACE);
//  screen = SDL_SetVideoMode(640, 480, 32, SDL_SWSURFACE|SDL_FULLSCREEN);
    bool running = true;
    const int FPS = 30;
    const int speed = 5;
    Uint32 start;
    int x,y;
    x = 0;
    y = 0;
    background = SDL_LoadBMP("background.bmp");
    image = SDL_LoadBMP("tree_key.bmp");
    SDL_SetColorKey(image, SDL_SRCCOLORKEY, SDL_MapRGB(screen->format, 0x00, 0xff, 0xff));
    SDL_Rect imgloc = {350,170,100,100};
    SDL_Rect camera;
    camera.x = 0;
    camera.y = 0;
    camera.w = 640;
    camera.h = 480;
    bool b[2] = {0,0};
    while(running) {
        start = SDL_GetTicks();
        SDL_Event event;
        while(SDL_PollEvent(&event)) {
            switch(event.type) {
                case SDL_QUIT:
                    running = false;
                    break;
                case SDL_KEYDOWN:
                    switch(event.key.keysym.sym)
                    {
                        case SDLK_RIGHT:
                            b[0] = 1;
                            break;
                        case SDLK_LEFT:
                            b[1] = 1;
                            break;
                        case SDLK_ESCAPE:
                            running = false;
                            break;
                    }
                    break;
                case SDL_KEYUP:
                    switch(event.key.keysym.sym)
                    {
                        case SDLK_RIGHT:
                            b[0] = 0;
                            break;
                        case SDLK_LEFT:
                            b[1] = 0;
                            break;
                    }
                    break;
            }
        }

        //logic
        if(b[0])
        {
            x += speed;
            camera.x += speed;
            if(camera.x >= 2000-640)
                camera.x = 0;
        }
        else if(b[1])
        {
            x -= speed;
            camera.x -= speed;
            if(camera.x <= 0)
                camera.x = 2000-640;
        }

        SDL_Rect location = {x,y,640,480};
        SDL_Rect relcoord = {imgloc.x-x, imgloc.y-y};

        //render
        SDL_BlitSurface(background, &camera, screen, NULL);
        if(collision(&location, &imgloc))
            SDL_BlitSurface(image, NULL, screen, &relcoord);

        SDL_Flip(screen);
        if(1000/FPS > SDL_GetTicks()-start) {
            SDL_Delay(1000/FPS-(SDL_GetTicks()-start));
        }
    }
    SDL_FreeSurface(background);
    SDL_FreeSurface(image);
    SDL_Quit();
    return 0;
}