Resize texture and get pixel

[lefsler]

Hi,

I need to resize a image and get each pixel (after the image is resized)..
I do the resize using

Code: [Select]

Texture tmpTexture;
tmpTexture.loadFromFile(tmp.str());
               
Sprite tmpSprite(tmpTexture);
tmpSprite.setScale(width/tmpSprite.getLocalBounds().width, height/tmpSprite.getLocalBounds().height);

But after that is possible to get the pixel after the resize operation is performed?

Regards

[eXpl0it3r]

There are multiple ways to go about this. What exactly are you going to do with the pixel information?

[lefsler]

i will generate some data about the R, G, B to do another stuff. In the end i am using the SFML library to do another thing, in the end i will just need to output 3 values to a text file, with (R, G, B).

[eXpl0it3r]

The thing is sf::Texture "lives" on the GPU, thus the best way would be to write a shader program.
Otherwise you'll have to render the scaled sprite to a render texture and convert the extracted texture to an sf::Image to get to the pixel info. This can be slow.

[Jesper Juhl]

If the idea is just to scale an image and then write it to a file in a new format, then I think I'd just use the convert tool from imagemagic and maybe a little python script for post-processing the text form.

[lefsler]

The thing is sf::Texture "lives" on the GPU, thus the best way would be to write a shader program.
Otherwise you'll have to render the scaled sprite to a render texture and convert the extracted texture to an sf::Image to get to the pixel info. This can be slow.

How do i convert the RenderTexture to image or Texture to Image.

What i did was:

Code: [Select]

Texture tmpTexture;
tmpTexture.loadFromFile(tmp.str());
               
Sprite tmpSprite(tmpTexture);
tmpSprite.setScale(width/tmpSprite.getLocalBounds().width, height/tmpSprite.getLocalBounds().height);
               
sf::RenderTexture renderTexture;
renderTexture.create(width, height);
renderTexture.draw(tmpSprite);
               
Texture t=renderTexture.getTexture();
Image imageOut.... How do i convert?


[G.]

There is only one method in the sf::Texture class which returns an sf::Image, easy to find. :p

[lefsler]

lol, thanks.

After i did that i try to save the image on a file (just to check the size) and i get.

JPEG parameter struct mismatch: library thinks size is 584, caller expects 568

What could be the problem?

The code is

Code: [Select]

Texture tmpTexture;
tmpTexture.loadFromFile(tmp.str());
Sprite tmpSprite(tmpTexture);
tmpSprite.setScale(width/tmpSprite.getLocalBounds().width, height/tmpSprite.getLocalBounds().height);
sf::RenderTexture renderTexture;
renderTexture.create(width, height);
renderTexture.draw(tmpSprite);
Texture t=renderTexture.getTexture();
Image imageOut =t.copyToImage();

tmp.str("");
tmp << "1" << entry->d_name;
imageOut.saveToFile(tmp.str());
cout << imageOut.getSize().x << endl;
cout << imageOut.getSize().y << endl;
tmp.str("");


[eXpl0it3r]

Why does everybody always forget to call either clear() or display() when it comes to the render texture?
For ever render target it's always clear, draw, display.

Googling the error message for like 1min told me, that your system most likely has a different version of libjpeg installed than the version SFML was built with. Are you on Linux?
Make sure the versions are the same.

[lefsler]

Ohh, so to render the texture i need to add the

clear.
...draw here
display.

What version does SFML use of the libjpg?

[eXpl0it3r]

Depends from where you got it and even more on with OS you are.