Best Way to get the position of an indexed pixel

[Weeve]

I guess a noob question, but I was wondering if sf::Sprite.GetMatrix() returns (X.x, X.y, 0, Y.x, Y.y,0,0,0,0), since it was claiming to be a Matrix3 (I assume SFML equiv of a Matrix3x3)? and if it does, is this data relevant to a sf::Sprite that has been rotated and scaled? or will it be relevant to its rotation, but have scaled vectors? and can I request that SFML will in the future have options to edit the Matrix directly, and that it will have a Matrix2.

or would it be wiser to construct the matrix myself, including the data I require? I want to know so that I can write a per-pixel collision function

[Laurent]

You're not supposed to use GetMatrix() directly, or know anything about the Matrix class of SFML. What are you trying to do?

SFML 2 has the sf::Transform public class, which wraps a 3x3 matrix. You can use it to transform any SFML entity.

[Weeve]

I want to get the current orientation of my Sprite as it looks on the screen, with  scale, and rotation, after I get its orientation, its all easy from there, I want to multiply a pixel array to it, (the pixel array is an outline of my Sprite), then do a pixel-pixel colision detect, instead of an AABB (eww  ), so I naturally faded to my mathematic roots by looking for a GetMatrix(),  looked at sf::Transform, and I'm not comprehending how to use it to get an orientation? and a raw matrix would be alot easier for me to work with, thanks! 

[Laurent]

Is that what you need?

sf::Transform transform = sprite.getTransform();
sf::Vector2f p = transform.transformPoint(sf::Vector2f(x, y));

sf::Transform is a matrix.

[Weeve]

Yes, ty that's exactly what I wanted to do, and I've decided each time I make some topics on the forum, to do some forum crawling to try to help give back to the community

[Weeve]

Ok.. so not exactly what I needed, I was using SFML 1.6, so I tried to use TransformToLocal(), but it kept having really odd results, I'm in the middle of switching to 2.0 right now, so that I can use Laurent's code snippet.. lowerCamelCase functions... Lord help me! I knew it would come to this eventually.

On a side note, did you change the image being stored to a vector in 2.0, or is it still an array? :-)

[Laurent]

I was using SFML 1.6, so I tried to use TransformToLocal(), but it kept having really odd results

Don't you need TransformToGlobal instead?

On a side note, did you change the image being stored to a vector in 2.0, or is it still an array?

Sorry, what are you talking about? And what's the difference between an array and a vector?

[Weeve]

tried transformToGlobal, but got similar problems, so I just made the switch

awhile back, I made mention that a sf::Image could only load an image up to a certain size, so I said it was probably being stored as an array, instead of a vector, and it was(I think) you that said you were going to change it in the update. the difference of an array and a vector, is that an array can't rescale, and it grabs the entire amount of ram (for a 32x32 image, for example, would still eat up whatever your max size in pixels is).

[Laurent]

Hmm... no. The image limit is the maximum texture size of the graphics card, and there's nothing I can do about it.

Array or vector, it's the same. The first is raw and requires a lot of code, the second is a wrapper and is easier to reallocate and to get correctly released. There's nothing you can do with one that you can't do with the other.