Problem with C++ SDL tutourial

Lab_Mouse

Hi All,
I just recently started a online SDL tutourial and am having problems already.
The bit of code should change the background from black to a colour,and leave the message "hello world"(you know you've along way to go when you see that quote in a tutourial!).

The code compiles fine but the background stays black,doesant change colour and the message doesnt show.

Im running xp pro and using VisualExpress 2008+SP1.

Any help much appreciated as im at me wits end over it!

Labmouse

#include "SDL.h"
#include<string>



//constant varibles
const int SCREEN_WIDTH=640;
const int SCREEN_HEIGHT=480;
const int SCREEN_BPP=32;//BPP=bits per pixel--32 bit colour!!!

//the surfaces that will be used

SDL_Surface *message=NULL;// "hello world!
SDL_Surface *background=NULL;//background image
SDL_Surface *screen=NULL;//screen

SDL_Surface *load_image(std::string filename)
{
    //temp storage for image thats stored
    SDL_Surface *loadedImage=NULL;

    //optimised image that will be used
    SDL_Surface *optimizedImage=NULL;

    //load the image
    loadedImage=SDL_LoadBMP(filename.c_str());

    //if nothing went wrong loading image
    if(loadedImage!=NULL)
    {
        //create an optimised image
        optimizedImage=SDL_DisplayFormat(loadedImage);

        //free the old image
        SDL_FreeSurface(loadedImage);
    }

        //return the opti image
        return optimizedImage;
    }

    void apply_surface(int x,int y,SDL_Surface*source,SDL_Surface*destination)
    {
   //make a temp rexct to hold the offsets
    SDL_Rect offset;

    //give the offsets to the rect;
    offset.x=x;
    offset.y=y;

    //draw the surface(image)
    SDL_BlitSurface(source,NULL,destination,&offset);
    }


    int main (int argc,char** args)
    {
        //init all sdl subsystems
        if(SDL_Init(SDL_INIT_EVERYTHING)==-1)
        {
            return 1;
        }

        //set up the screen
        screen=SDL_SetVideoMode(SCREEN_WIDTH,SCREEN_HEIGHT,SCREEN_BPP,SDL_SWSURFACE);
        //if error in setting up screen
        if(screen==NULL)
        {
            return 1;
        }

        //set window caption
        SDL_WM_SetCaption("hello World",NULL);

        //load the images
        message=load_image("hello_world.bmp");
        background=load_image("background.bmp");

        //apply background to the screen
        apply_surface(0,0,background,screen);

        //apply message to screen
        apply_surface(180,140,message,screen);

        //update the screen
        if(SDL_Flip(screen)==-1)
        {
            return 1;
        }

        //wait 2 seconds
        SDL_Delay(2000);


        //free surfaces
        SDL_FreeSurface(message);
        SDL_FreeSurface(background);

        //quitsdl
        SDL_Quit();
        return 0;

    }

sicruise

note:I haven't looked at your code integrity.

The first obvious question is... are the image files actually in your debug/project folder? It may be easier for you to specify the exact path.

Lab_Mouse

hi sicruise..that hadnt occurred to me.The images arent stored in the debugg file..in the tutourial he had the SDL files on his c drive whereas i have it in my documents and have it linked to there..will move the sdl folder and see if that gets it going.

How would you set the path for the images?

thanks for tyhe quick reply

the image IS in the debug folder so i thimk it is looking else where for the image.

again excuse my ignorance

sicruise

Just change

message=load_image("hello_world.bmp");

to

message=load_image("c:\\location\\hello_world.bmp");

No problem... its usually something simple that gets you stuck at the start.

Lab_Mouse

Thanks sicruise that worked straight off..Will know next time to check the paths for the bitmaps

sicruise

No problem, glad you got it sorted.

SirLemonhead

You can also do

message=load_image("c:/location/hello_world.bmp");

which looks nicer and might be less problematic in certain cases