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Jiroh

[SDL] IMG_Load failure (Lazyfoo tut)

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Hi all, I'm attempting to compile Lazyfoo's tutorial number 20 on MS Visual Studio 2008. So far it compiles but it doesn't load the image. Here's the code, with minor alterations from the tutorial. Any ideas why the idea will not load? The foo.png file is on the debug folder. I'm using SDL-1.2.13.
//http://lazyfoo.net/SDL_tutorials/lesson20/index.php
//#include <stdlib.h> was placed by me
#include <stdio.h>
#include <stdlib.h>
//The headers
#include "SDL.h"
#include "SDL_image.h"
#include <string>

//optional
/* -- Include the precompiled libraries -- */
    #ifdef WIN32
    #pragma comment(lib, "SDL.lib")
    #pragma comment(lib, "SDLmain.lib")	
	#pragma comment(lib, "SDL_image.lib")
    #endif 

//Screen attributes
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
const int SCREEN_BPP = 32;

//The frames per second
const int FRAMES_PER_SECOND = 10;

//The dimensions of the stick figure
const int FOO_WIDTH = 64;
const int FOO_HEIGHT = 205;

//The direction status of the stick figure
const int FOO_RIGHT = 0;
const int FOO_LEFT = 1;

//The surfaces
SDL_Surface *foo = NULL;
SDL_Surface *screen = NULL;

//The event structure
SDL_Event event;

//The areas of the sprite sheet
SDL_Rect clipsRight[ 4 ];
SDL_Rect clipsLeft[ 4 ];

//The stick figure
class Foo
{
    private:
    //The offset
    int offSet;
    
    //Its rate of movement
    int velocity;
    
    //Its current frame
    int frame;
    
    //Its animation status
    int status;

    public:
    //Initializes the variables
    Foo();
    
    //Handles input
    void handle_events();
    
    //Moves the stick figure
    void move();    
    
    //Shows the stick figure
    void show();    
};

//The timer
class Timer
{
    private:
    //The clock time when the timer started
    int startTicks;
    
    //The ticks stored when the timer was paused
    int pausedTicks;
    
    //The timer status
    bool paused;
    bool started;
    
    public:
    //Initializes variables
    Timer();
    
    //The various clock actions
    void start();
    void stop();
    void pause();
    void unpause();
    
    //Gets the timer's time
    int get_ticks();
    
    //Checks the status of the timer
    bool is_started();
    bool is_paused();    
};

//SDL_Surface *load_image( std::string filename ) 
SDL_Surface *load_image( char* filename ) 
{
	printf("\nAccessed load_image function\n");
    //The image that's loaded
    SDL_Surface* loadedImage = NULL;
	printf("\nSet loadedImage to NULL\n");
    
    //The optimized surface that will be used
    SDL_Surface* optimizedImage = NULL;
    printf("\nSet optimizedImage to NULL\n");
    //Load the image
    loadedImage = IMG_Load( filename.c_str() );
	
	printf("\nIMG_Load function accessed\n");
    //If the image loaded
    if( loadedImage != NULL )
    {
		printf("\nSet loadedImage not NULL\n");
        //Create an optimized surface
        optimizedImage = SDL_DisplayFormat( loadedImage );
        
        //Free the old surface
        SDL_FreeSurface( loadedImage );
        
        //If the surface was optimized
        if( optimizedImage != NULL )
        {
            //Color key surface
            SDL_SetColorKey( optimizedImage, SDL_SRCCOLORKEY, SDL_MapRGB( optimizedImage->format, 0, 0xFF, 0xFF ) );
        }
    }
    
    //Return the optimized surface
    return optimizedImage;
}

void apply_surface( int x, int y, SDL_Surface* source, SDL_Surface* destination, SDL_Rect* clip = NULL )
{
    //Holds offsets
    SDL_Rect offset;
    
    //Get offsets
    offset.x = x;
    offset.y = y;
    
    //Blit
    SDL_BlitSurface( source, clip, destination, &offset );
}

void set_clips()
{
    //Clip the sprites
    clipsRight[ 0 ].x = 0;
    clipsRight[ 0 ].y = 0;
    clipsRight[ 0 ].w = FOO_WIDTH;
    clipsRight[ 0 ].h = FOO_HEIGHT;
    
    clipsRight[ 1 ].x = FOO_WIDTH;
    clipsRight[ 1 ].y = 0;
    clipsRight[ 1 ].w = FOO_WIDTH;
    clipsRight[ 1 ].h = FOO_HEIGHT;
    
    clipsRight[ 2 ].x = FOO_WIDTH * 2;
    clipsRight[ 2 ].y = 0;
    clipsRight[ 2 ].w = FOO_WIDTH;
    clipsRight[ 2 ].h = FOO_HEIGHT;
    
    clipsRight[ 3 ].x = FOO_WIDTH * 3;
    clipsRight[ 3 ].y = 0;
    clipsRight[ 3 ].w = FOO_WIDTH;
    clipsRight[ 3 ].h = FOO_HEIGHT;
    
    clipsLeft[ 0 ].x = 0;
    clipsLeft[ 0 ].y = FOO_HEIGHT;
    clipsLeft[ 0 ].w = FOO_WIDTH;
    clipsLeft[ 0 ].h = FOO_HEIGHT;
    
    clipsLeft[ 1 ].x = FOO_WIDTH;
    clipsLeft[ 1 ].y = FOO_HEIGHT;
    clipsLeft[ 1 ].w = FOO_WIDTH;
    clipsLeft[ 1 ].h = FOO_HEIGHT;
    
    clipsLeft[ 2 ].x = FOO_WIDTH * 2;
    clipsLeft[ 2 ].y = FOO_HEIGHT;
    clipsLeft[ 2 ].w = FOO_WIDTH;
    clipsLeft[ 2 ].h = FOO_HEIGHT;
    
    clipsLeft[ 3 ].x = FOO_WIDTH * 3;
    clipsLeft[ 3 ].y = FOO_HEIGHT;
    clipsLeft[ 3 ].w = FOO_WIDTH;
    clipsLeft[ 3 ].h = FOO_HEIGHT;
}

bool init()
{
    //Initialize all SDL subsystems
    if( SDL_Init( SDL_INIT_EVERYTHING ) == -1 )
    {
        return false;    
    }
    
    //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 false;    
    }
    
    //Set the window caption
    SDL_WM_SetCaption( "Animation Test", NULL );
    
    //If everything initialized fine
    return true;
}

bool load_files()
{
	printf("\nNow loading sprite sheet\n");
    //Load the sprite sheet
	foo = load_image( "foo.png" );
    
    //If there was a problem in loading the sprite
    if( foo == NULL )
    {	
		printf("\nFailed load_files function!\n");
        return false;    
    }
    
    //If everything loaded fine
    return true;
}

void clean_up()
{
    //Free the surface
    SDL_FreeSurface( foo );
    
    //Quit SDL
    SDL_Quit();
}

Foo::Foo()
{
    //Initialize movement variables
    offSet = 0;
    velocity = 0;
    
    //Initialize animation variables
    frame = 0;
    status = FOO_RIGHT;
}

void Foo::handle_events()
{
    //If a key was pressed
    if( event.type == SDL_KEYDOWN )
    {
        //Set the velocity
        switch( event.key.keysym.sym )
        {
            case SDLK_RIGHT: velocity += FOO_WIDTH / 4; break;
            case SDLK_LEFT: velocity -= FOO_WIDTH / 4; break;
        }
    }
    //If a key was released
    else if( event.type == SDL_KEYUP )
    {
        //Set the velocity
        switch( event.key.keysym.sym )
        {
            case SDLK_RIGHT: velocity -= FOO_WIDTH / 4; break;
            case SDLK_LEFT: velocity += FOO_WIDTH / 4; break;
        }
    }
}

void Foo::move()
{
    //Move
    offSet += velocity;
    
    //Keep the stick figure in bounds
    if( ( offSet < 0 ) || ( offSet + FOO_WIDTH > SCREEN_WIDTH ) )
    {
        offSet -= velocity;    
    }
}

void Foo::show()
{
    //If Foo is moving left
    if( velocity < 0 )
    {
        //Set the animation to left
        status = FOO_LEFT;
        
        //Move to the next frame in the animation
        frame++;
    }
    //If Foo is moving right
    else if( velocity > 0 )
    {
        //Set the animation to right
        status = FOO_RIGHT;
        
        //Move to the next frame in the animation
        frame++;
    }
    //If Foo standing
    else
    {
        //Restart the animation
        frame = 0;    
    }
    
    //Loop the animation
    if( frame >= 4 )
    {
        frame = 0;
    }
    
    //Show the stick figure
    if( status == FOO_RIGHT )
    {
        apply_surface( offSet, SCREEN_HEIGHT - FOO_HEIGHT, foo, screen, &clipsRight[ frame ] );
    }
    else if( status == FOO_LEFT )
    {
        apply_surface( offSet, SCREEN_HEIGHT - FOO_HEIGHT, foo, screen, &clipsLeft[ frame ] );
    }
}

Timer::Timer()
{
    //Initialize the variables
    startTicks = 0;
    pausedTicks = 0;
    paused = false;
    started = false;    
}

void Timer::start()
{
    //Start the timer
    started = true;
    
    //Unpause the timer
    paused = false;
    
    //Get the current clock time
    startTicks = SDL_GetTicks();    
}

void Timer::stop()
{
    //Stop the timer
    started = false;
    
    //Unpause the timer
    paused = false;    
}

void Timer::pause()
{
    //If the timer is running and isn't already paused
    if( ( started == true ) && ( paused == false ) )
    {
        //Pause the timer
        paused = true;
    
        //Calculate the paused ticks
        pausedTicks = SDL_GetTicks() - startTicks;
    }
}

void Timer::unpause()
{
    //If the timer is paused
    if( paused == true )
    {
        //Unpause the timer
        paused = false;
    
        //Reset the starting ticks
        startTicks = SDL_GetTicks() - pausedTicks;
        
        //Reset the paused ticks
        pausedTicks = 0;
    }
}

int Timer::get_ticks()
{
    //If the timer is running
    if( started == true )
    {
        //If the timer is paused
        if( paused == true )
        {
            //Return the number of ticks when the timer was paused
            return pausedTicks;
        }
        else
        {
            //Return the current time minus the start time
            return SDL_GetTicks() - startTicks;
        }    
    }
    
    //If the timer isn't running
    return 0;    
}

bool Timer::is_started()
{
    return started;    
}

bool Timer::is_paused()
{
    return paused;    
}

int main( int argc, char* args[] )
{
    //Quit flag
    bool quit = false;
    
    //Initialize
    if( init() == false )
    {
        return 1;
    }
    
    //Load the files
    if( load_files() == false )
    {
		printf("\nFailed to load files!\n");
        return 1;
    }
    
    //Clip the sprite sheet
    set_clips();

    //The frame rate regulator
    Timer fps;
    
    //The stick figure
    Foo walk;
    
    //While the user hasn't quit
    while( quit == false )
    {
        //Start the frame timer
        fps.start();
    
        //While there's events to handle
        while( SDL_PollEvent( &event ) )
        {
            //Handle events for the stick figure
            walk.handle_events();
            
            //If the user has Xed out the window
            if( event.type == SDL_QUIT )
            {
                //Quit the program
                quit = true;
            }
        }
        
        //Move the stick figure
        walk.move();
        
        //Fill the screen white
        SDL_FillRect( screen, &screen->clip_rect, SDL_MapRGB( screen->format, 0xFF, 0xFF, 0xFF ) );
        
        //Show the stick figure on the screen
        walk.show();
        
        //Update the screen
        if( SDL_Flip( screen ) == -1 )
        {
            return 1;    
        }
        
        //Cap the frame rate
        if( fps.get_ticks() < 1000 / FRAMES_PER_SECOND )
        {
            SDL_Delay( ( 1000 / FRAMES_PER_SECOND ) - fps.get_ticks() );
        }
    }
        
    //Clean up
    clean_up();
    
    return 0;    
}

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To answer my own question: the debug exe couldn't find the png because I did not set a working directory in the debugger settings.

Still, I wonder why foo = load_image( "C:\foo.png" ); did not work. I had a copy of the png on C.

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Quote:
Original post by Jiroh
To answer my own question: the debug exe couldn't find the png because I did not set a working directory in the debugger settings.

Still, I wonder why foo = load_image( "C:\foo.png" ); did not work. I had a copy of the png on C.


That's a common mistake. Pay attention to the backslash character in C strings. Remember that the backslash will trigger an escape seqeuence. In this case, it does nothing and the resulting C string would be "C:foo.png". To put a backslash in a C string, use "C:\\foo.png". The double-backslash will put a single backslash in the C string.

Edit: I see \f is actually an escape sequence, it generates a form feed character.

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