How can I make sprites from multiple images using SDL2?

Question

Using SDL2 in C++ I can load textures with out problem however, I have sprites that are from about 15 different png's that I was hoping I could load them all up and for loop through them. However, when I try this it looks like the image is still .

I am hoping that I wouldn’t have to photo shop them into one image and shift/pan through that considering I have about 3K of images to go through.

can some one provide an example of how this could be done cleanly?

I have been working on this for a while for a bit and yes, this is probably a coding mistake as I am learning C++ still and know that for me to learn is to take up a project.

int main ( int argc, char *argv[] )
{

    SDL_Init(SDL_INIT_EVERYTHING);
    Window = SDL_CreateWindow("NEW WINDOW",100,100,300,300,SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE);
    renderer = SDL_CreateRenderer(Window,-1,SDL_RENDERER_ACCELERATED);

    if (Window == NULL)
    {
        std::cout << "Window Couldn't be Created!\n";
    }

    struct imagebatch
    {
        const char *image;
    };

    imagebatch foto;

    //  A for loop is needed here to loop through Healer0.png Healer1.png to Healer15.png
    foto.image = "DData/towners/healer/healer/Healer0.png";
    HealerTexture = IMG_LoadTexture(renderer,foto.image);

    //loads an image;
    //HealerTexture = IMG_LoadTexture(renderer,"DData/towners/healer/healer/Healer0.png");

    //defines the rect of this image;
    SDL_Rect HealerRect;
    HealerRect.x = 0;
    HealerRect.y = 0;
    HealerRect.w = 90;
    HealerRect.h = 90;

    while (!quit)
    {
        while( SDL_PollEvent( &event ) != 0 )
        {
            //User requests quit
            if( event.type == SDL_QUIT )
            {
                quit = true;
            }
        }
        SDL_RenderClear(renderer);

        //Blit everything here.
        SDL_RenderCopy(renderer,HealerTexture,NULL,&HealerRect);

        SDL_RenderPresent(renderer);
    }
    close();

    return 0;
}

Full code is here: http://pastebin.com/H5fD6cfX

Answer 1

For loading the images, you could do:

std::vector<imagebatch> fotos;
std::vector<SDL_Texture*> healerTexture;

// Parts of filename string that occur multiple times.
char* filenameBase = "DData/towners/healer/healer/Healer";
char* fileExt = ".png";

// This is 15 because of the number of images there are.
for (int i = 0; i < 15; ++i)
{
    char filename[64];
    strcpy(filename, filenameBase); // Copy the first part of the filename into the variable filename.

    char fileIndex[4]; // Create a string of length 4 for storing converted numbers.

    sprintf(fileIndex, "%d", i); // Convert i to a number (that's what %d specifies) and store in fileIndex
    strcat(filename, strcat(fileIndex, fileExt)); // Append the number to filename, and then append the file extension to that.

    // Create a new imagebatch to push onto the imagebatch vector.
    imagebatch foto;
    foto.image = filename;
    fotos[i].push_back(foto);

    // Finally, load the filename that we generated.
    healerTexture.push_back(IMG_LoadTexture(foto.image));
}

You may want to double check the string manipulation code, although I highly recommend std::string where possible with boost::lexical_cast since you won't be using it in a very performance sensitive area.

I've also used std::vector which is better because you don't have to pick their max length before compiling the code (amongst other things).

Don't forget to include vector and string at the top of each file if you use them as follows:

#include <vector>
#include <string>

And finally, when you want to render a particular sprite, you can do the following:

int spriteToRender = 5; // Edit this to the sprite you need to render.
SDL_RenderCopy(renderer,healerTexture[spriteToRender],NULL,&healerRect);

Answer 2

I highly recommend you look into spritesheets, for memory efficiency/performance. There are a couple of tools out there to help you convert your collection of images into a spritesheet, such as SpriteSheetPacker (open source) or my Gimp plugin for it. A quick google found me this sdl2 tutorial on spritesheets.