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Author Topic: A slight problem with drawing sprites  (Read 3098 times)

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Calmatory

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A slight problem with drawing sprites
« on: July 21, 2010, 10:11:19 pm »
Well, I came across this kind of a problem while writing a tetris clone, and I'm kind of stuck with this problem for now.

The first two sprites just draw a white box, I don't know why. As if not all the images in vector seem to be valid for some reason?

This code should well reproduce the problem. block.png should be a png file with 16x16 dimensions.

Code: [Select]

#include <SFML/System.hpp>
#include <SFML/Graphics.hpp>
#include <string>
#include <vector>

/* Define global vector to hold all loaded images. */
std::vector<sf::Image> tempVector;

sf::Sprite LoadImage(std::string filename) {
    sf::Image tempImage;
    if(tempImage.LoadFromFile(filename)) {
        sf::Sprite tempSprite;
        tempVector.push_back(tempImage);
        tempSprite.SetImage(tempVector.back());
        return tempSprite;
    }
}

int main() {

    sf::RenderWindow App(sf::VideoMode(320,240,32), "Bugtest");
   
    sf::Sprite sprite[4];

    sprite[0] = LoadImage("block.png");
    sprite[1] = LoadImage("block.png");
    sprite[2] = LoadImage("block.png");
    sprite[3] = LoadImage("block.png");
    int i=0;

    for(int y=0;y<240;y+=16) {
        for(int x=0;x<320;x+=16) {
            sprite[i%4].SetPosition(x,y);
            App.Draw(sprite[i%4]);
            i++;
        }
    }
    App.Display();
    sf::Sleep(10.0f);
    App.Close();

}


Using linux x86 with SFML 1.6 and gcc version 4.5.0 20100610 (prerelease) (GCC).
The amount of effort we put into something arbitrary we do in our everyday lives is proportional to the amount we gain from it. It's fascinating how this applies to everything in our lives. Your task is to try to enjoy and make the most out of it.

Laurent

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A slight problem with drawing sprites
« Reply #1 on: July 21, 2010, 11:29:54 pm »
When the vector needs to grow, it may move its elements elsewhere in memory. This is what invalidates some of the image pointers that the sprites store. You should rather use a container which never invalidates its elements, such as std::list, std::set or std::map.
Laurent Gomila - SFML developer

Calmatory

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A slight problem with drawing sprites
« Reply #2 on: July 22, 2010, 12:06:31 am »
Using std::list solved the problem. Thanks for the info. :) ...and now my journey shall continue.
The amount of effort we put into something arbitrary we do in our everyday lives is proportional to the amount we gain from it. It's fascinating how this applies to everything in our lives. Your task is to try to enjoy and make the most out of it.

CBenni::O

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A slight problem with drawing sprites
« Reply #3 on: July 22, 2010, 04:04:15 pm »
Or, if you need random access, use std::vector<sf::Image*> (I know this isn't perfect Code, remember that you have to release all pointers manually, or use boost::ptr_vector or std::vector< shared_ptr<sf::Image> >.

bye, CBenni::O
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