Transform Anchor

[DanielDK05]

What problem does this solve or what need does it fill?

It would be nice to set an anchor point, like you can on Sprite, on either the transform or mesh.
I am currently creating a game where I would benefit from anchoring the transform on the bottom of the entity.

What solution would you like?

I am envisioning a new component, like this:

enum TransformAnchor {
   Center,
   TopLeftFront,
   TopLeftCenter,
   TopLeftBack,
   TopRightFront,
   Custom(Vec3)
   etc...
}

commands.spawn((
   Transform::default(),
   TransformAnchor::BottomCenter,
));

What alternative(s) have you considered?

An alternative would of course be to just offset the transform manually, but I find that a bit tedious to work with.

[KingBright]

I wonder if there is any method to rotate an image (or a sprite) on a specific anchor point?

[copygirl]

Not sure if @DanielDK05's enum type is ideal. Wouldn't a wrapper type around Vec3 with some consts be sufficient?

struct TransformAnchor(pub Vec3);

impl TransformAnchor {
    pub const TopLeftFront: Self = TransformAnchor(Vec3(...));
    // ...
}

(Been a little while since I've done Rust so there might be some silliness in my example code.)

Also I'm not super familiar with Bevy. Is "top", "left", "front" defined or left up to the developer?

[DanielDK05]

@copygirl I agree with this. I don't remember my exact thoughts when I made this issue, but a Vec3 wrapper seems like the most logical solution.