reset Transform?

[Stauricus]

hello everybody

how can I reset a transform? i noticed that if i use

state.transform.translate =  sf::Vector2f(10, 0);

twice, the final position will be (20, 0). i know that it is expected, but, how can i make it to be always (10, 0)?

what i'm trying to do is move some vertexArrays to specific positions on the screen, so i can't just combine the "translate" values.

thanks in advance

[verdog]

As far as I know, that's not the proper way to use a transform. I think you should be doing it like this:

state.transform.translate(sf::Vector2f(10, 0));

And to reset it, I think you could do

state.transform = sf::Transform::Identity;

[Stauricus]

you are right, the correct usage indeed is

state.transform.translate(sf::Vector2f(10, 0));

i was in a rush and typed it wrong. 

now, sf::Transform::Identity is a good idea, but it also resets scale and rotation. what if i want to reset only the translate value?

[Laurent]

sf::Transform is a matrix. It does not remember how it was built: whether it was with translations, rotations, scales, or a combination of those... in the end you have a combined matrix from which you can't get back information (almost).

So, while technically there's a way to cancel the translation by directly accessing the elements of the matrix, I can't imagine why you would have to do that in the context of render states.

[Stauricus]

well, i have a vertexArray, which i want to rotate, move, and then put it back in it's original position and rotation. so i was using render states for that.

but it just figured out how stupid it is, since i could just create a class inheriting from VertexArray and sf::Transformable, and then have access to functions like getRotation()

thanks for the answers!

[Laurent]

You can also use an instance of sf::Transformable as a member, rather than as a base class. This has the benefit of not polluting your class API with all the sf::Transformable functions, if you don't need to expose them.

sf::Transformable transforms;
transforms.setPosition(...);
window.draw(vertexArray, transforms.getTransform());

[Stauricus]

even better. i'll do it, then. thanks for the help