Home
Blogs
Forums
News
Portfolios
Projects
Tutorials
31 users logged in
New? Learn about game development.
Before posting, review our community guidelines.
Follow Us
Chat in the GameDev.net Discord!
Mastodon
Back to For Beginners

Beginning SDL Problem

Started by
6 comments, last by NUCLEAR RABBIT 15 years, 11 months ago
Hello, I tried making something with SDL, Im getting no errors, but when I run the program, a window pops up and just goes away and it doesnt show the image. Can anyone help me find what I am doing wrong? 

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

const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
const int SCREEN_BPP = 32;

SDL_Surface * screen = NULL;
SDL_Surface * message = NULL;
SDL_Surface * background = NULL;

void CleanUp();
bool Init();
bool LoadFiles();
SDL_Surface * LoadImage(const std::string & file_name);
void ApplyImage(int x, int y, SDL_Surface * image, SDL_Surface * screen);

int main( int argc, char* args[] )
{
	if(Init() == false)
	{
		return 1;
	}

	if(LoadFiles() == false)
	{
		return 1;
	}

	ApplyImage(0,0,background,screen);
	ApplyImage(0,0,message,screen);

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

	CleanUp();

	return 0;
}

//____________________________________________________________________________________________________________________

// Function Definitions

void CleanUp()
{
	SDL_Delay(5000);
	SDL_FreeSurface(background);
	SDL_FreeSurface(message);
	SDL_Quit();
}

bool Init()
{
	if(SDL_Init(SDL_INIT_EVERYTHING) == -1)
	{
		return false;
	}

	screen = SDL_SetVideoMode(SCREEN_WIDTH, SCREEN_HEIGHT,SCREEN_BPP,SDL_SWSURFACE);

	if(screen == NULL)
	{
		return false;
	}

	SDL_WM_SetCaption("ADDING AN IMAGE TO THE SCREEN!", NULL);

	return true;
}

bool LoadFiles()
{
	background = LoadImage("background.bmp");
	message = LoadImage("hello_world.bmp");

	if (background == NULL || message == NULL)
	{
		return false;
	}

	return true;
}

SDL_Surface * LoadImage(const std::string & file_name)
{
	SDL_Surface * loaded_image = NULL;
	SDL_Surface * opt_image = NULL;

	loaded_image = SDL_LoadBMP(file_name.c_str());

	if(loaded_image != NULL)
	{
		opt_image = SDL_DisplayFormat(loaded_image);

		SDL_FreeSurface(loaded_image);
	}

	return opt_image;
}

void ApplyImage(int x, int y, SDL_Surface * image, SDL_Surface * screen)
{
	SDL_Rect offset;

	offset.x = x;
	offset.y = y;

	SDL_BlitSurface(image, NULL, screen, &offset);
}
Advertisement
Quote:Original post by NUCLEAR RABBIT
Hello,

I tried making something with SDL, Im getting no errors, but when I run the program, a window pops up and just goes away and it doesnt show the image. Can anyone help me find what I am doing wrong?

*** Source Snippet Removed ***


That's what your code does - inits SDL, loads the files, draws the images, flips the screen then calls cleanup and finishes :)

You need a 'main loop'.

"The right, man, in the wrong, place, can make all the dif-fer-rence in the world..." - GMan, Half-Life 2

A blog of my SEGA Megadrive development adventures: http://www.bigevilcorporation.co.uk

lol, you're lucky, I can compile just fine, but when i try to execute the program nothing happens....

#include <SDL\SDL.h>#include <string>const int SCREEN_WIDTH = 640;const int SCREEN_HEIGHT = 480;const int SCREEN_BPP = 32;SDL_Surface *message = NULL;SDL_Surface *background = NULL;SDL_Surface *screen = NULL;void apply_surface( int x, int y, SDL_Surface* source, SDL_Surface* destination ){    //Make a temporary rectangle to hold the offsets    SDL_Rect offset;        //Give the offsets to the rectangle    offset.x = x;    offset.y = y;        //Blit the surface    SDL_BlitSurface( source, NULL, destination, &offset );}SDL_Surface *load_image( std::string filename ){    SDL_Surface* loadedImage = NULL;    SDL_Surface* optimizedImage = NULL;        loadedImage = SDL_LoadBMP( filename.c_str() );        if( loadedImage != NULL )    {        optimizedImage = SDL_DisplayFormat( loadedImage );        SDL_FreeSurface( loadedImage );    }    return optimizedImage;}int main( int argc, char* args[] ){    //Start SDL    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 there was an error in setting up the screen    if( screen == NULL )    {        return 1;        }    //Set the window caption    SDL_WM_SetCaption( "Hello World", NULL );    //Load the images    message = load_image( "hello_world.bmp" );    background = load_image( "background.bmp" );    //Apply the background to the screen    apply_surface( 0, 0, background, screen );    //Apply the message to the screen    apply_surface( 180, 140, message, screen );    //Update the screen    if( SDL_Flip( screen ) == -1 )    {        return 1;        }    //Wait 20 seconds    SDL_Delay( 20000 );    //Free the surfaces    SDL_FreeSurface( message );    SDL_FreeSurface( background );        //Quit SDL    SDL_Quit();        //Return    return 0;}
-A.K.A SteveGravity is unreliable-DTD
Quote:Original post by deadstar
Quote:Original post by NUCLEAR RABBIT
Hello,

I tried making something with SDL, Im getting no errors, but when I run the program, a window pops up and just goes away and it doesnt show the image. Can anyone help me find what I am doing wrong?

*** Source Snippet Removed ***


That's what your code does - inits SDL, loads the files, draws the images, flips the screen then calls cleanup and finishes :)

You need a 'main loop'.


haha yah, but in the CleanUp(), i put a delay function, which delays the window for 5 seconds so I can see the images before it closes.

(it only stays up for like a split second)
Ah I did notice after I posted.

I wouldn't rely on that SDL_delay() too much.

Best advice I can give is to output error messages in all your error checking. Use 'cout' or 'printf', or if you're using Windows then include windows.h and use a message box:

MessageBox(NULL, "Error initialising SDL", "Error", MB_OK);


And that Main Loop still comes highly recommended.

"The right, man, in the wrong, place, can make all the dif-fer-rence in the world..." - GMan, Half-Life 2

A blog of my SEGA Megadrive development adventures: http://www.bigevilcorporation.co.uk

Quote:Original post by deadstar

And that Main Loop still comes highly recommended.


yah, i know. im just trying to get an image on the screen for right now [smile]

ill try the messagebox to find the error :D

thanx!
one problem with the message box, i get this error when i put that in:

1>c:\users\owner\documents\visual studio 2008\projects\sdl lesson 2\sdl lesson 2\main.cpp(68) : error C2664: 'MessageBoxW' : cannot convert parameter 2 from 'const char [5]' to 'LPCWSTR'
	if(SDL_Init(SDL_INIT_EVERYTHING) == -1)	{		MessageBox(NULL, "INIT", "ERROR", MB_OK);		return false;	}


(I added <windows.h>)
nevermind, my friend helped me find the error :D

(the images were in the wrong directory haha

thanx tho!

This topic is closed to new replies.

Advertisement

Popular Topics

Aybe One
How do you manage yourself and your time as years pass on? GDNet Lounge
Jikoob
Too many managers? General and Gameplay Programming
ReignOnU
Do your part to stop global warming and climate change GDNet Lounge
Konjointed
C++ how do you use dependency injection? For Beginners
aigan
The promise of freedom in story games Game Design and Theory
robertrobert
Facebook Ads for sales on steam, does it work? Games Business and Law
Advertisement

Recommended Tutorials

Spunya
Making a Game with Blend4Web Part 2: Models for the Location Engines and Middleware
frob
Data Structures for Pre-College Programmers: Stacks and Queues General and Gameplay Programming
Myopic Rhino
Loading Bitmap Files into DirectDraw Graphics and GPU Programming
Martin Perry
Basic OpenAL sound manager for your project General and Gameplay Programming
GameDev.net
Interview: Cliff Harris on What it Takes to Become a Successful Game Developer Interviews

Reticulating splines

About GameDev.net
Community Guidelines
Terms of Service
Privacy Policy
Contact Us
Copyright (c) 1999-2024 GameDev.net, LLC
Back to Top