sf::Texture and sf::RenderTexture.getTexture

[Mina66]

Hello
There is such a code

    sf::Sprite sprite_1;
    sf::Texture texture;
    texture.loadFromFile("d:\\1.png");
    sprite_1.setTexture(texture);

    sf::RenderTexture renderTexture;
    renderTexture.create(96, 96);
    renderTexture.clear(sf::Color(255, 255, 255, 0));
    renderTexture.draw(sprite_1);
    renderTexture.display();

    sf::Sprite sprite_2;
    sprite_2.setTexture(renderTexture.getTexture());
    sprite_2.setPosition(97.f, 0.f);

....

   Window.clear(sf::Color(128, 128, 128));
   Window.draw(sprite_1);
   Window.draw(sprite_2);
   Window.display();

 

Please explain why little difference between pictures. (the shadow)




Sorry for the English.

[Ixrec]

My guess is the difference in the two clear() commands is the cause.  Try specifying an alpha value in the second one, or simply giving them the exact same color arguments, and see if that makes it obvious what's happening.

[Mina66]

changed, there is a difference

    renderTexture.clear(sf::Color(128, 128, 128, 0));

....

   Window.clear(sf::Color(128, 128, 128, 0));

 

[Ixrec]

Well I have one other guess: try setSmooth with true and false.

If that doesn't work we'll have to hope someone smarter than me shows up.

[Siile]

Instead of transparent white have you tried using transparent black?

renderTexture.clear(sf::Color(0, 0, 0, 0));

[Mina66]

Well I have one other guess: try setSmooth with true and false.

If that doesn't work we'll have to hope someone smarter than me shows up.

changed, there is a difference

    renderTexture.setSmooth(true);
    renderTexture.clear(sf::Color(128, 128, 128, 0));

....

   Window.clear(sf::Color(128, 128, 128, 0));

 

[Mina66]

Instead of transparent white have you tried using transparent black?

renderTexture.clear(sf::Color(0, 0, 0, 0));

changed, there is a difference

    renderTexture.clear(sf::Color(0, 0, 0, 0));

....

   Window.clear(sf::Color(128, 128, 128, 0));

 

[Laurent]

There problem here is that alpha (transparency) is applied twice when you first draw to a render-texture. You can play with clear values, the result will never be the same.

The only way to have the same result is not to apply alpha when you draw to the render-texture:

renderTexture.clear(sf::Color(0, 0, 0, 0));
renderTexture.draw(sprite_1, sf::BlendNone);
renderTexture.display();

[Ixrec]

Oh wow, that explains so much.

Does RenderWindow do this too?

[Mina66]

Thanks a lot, Laurent 

here is the result

[Laurent]

Does RenderWindow do this too?

Does it do what?

[Ixrec]

Apply alpha twice when you first draw to it.

[Laurent]

when you first draw to it

... and then draw it to what? RenderWindow is usually the final target

In this case, alpha is applied twice because the sprite is drawn twice: once to the render-texture, and then the render-texture is drawn to the render-window.

[Ixrec]

Ah, that's what you meant.  Okay, I think I got it now.