fix: Absolute angle takes into account BodyComponent ancestors too

[maurovanetti]

Description

Currently, the implementation of the absoluteAngle getter in PositionComponent only takes into account PositionComponent ancestors. The implementation simply runs through the whole hierarchy summing up the relative angles.

This gives a wrong result with Forge2D because BodyComponents have angles too: in the common situation where a PositionComponent (e.g. a SpriteComponent) is the child of a BodyComponent, the BodyComponent's rotation is ignored when computing the absoluteAngle.

The fix simply introduces a new minimal interface HasAngle that both PositionComponent and BodyComponent implement (PositionComponent implements it automatically via AngleProvider), and reimplements absoluteAngle so that it considers all ancestors with an angle and not just the PositionComponent ones.

Checklist

• I have followed the [Contributor Guide] when preparing my PR.
• I have updated/added tests for ALL new/updated/fixed functionality.
• I have updated/added relevant documentation in docs and added dartdoc comments with ///.
• I have updated/added relevant examples in examples or docs.

Breaking Change?

• Yes, this PR is a breaking change.
• No, this PR is not a breaking change.

[spydon]

Good idea! HasAngle should be named ReadOnlyAngleProvider though, to follow the new conventions set by ReadOnlySizeProvider.

[maurovanetti]

Good idea! HasAngle should be named ReadOnlyAngleProvider though, to follow the new conventions set by ReadOnlySizeProvider.

Oops, I missed it. But it's got a lower-case O for some reason.

Updated.

[spydon]

But it's got a lower-case O for some reason.

Since it hasn't been exported previously, do you mind renaming it to ReadOnlySizeProvider and same with ReadOnlyAngleProvider, and add that one to the export too? :)

(You can sneak it into this PR too)

[maurovanetti]

There we go.

[spydon]

Lgtm!