feat: MoveAlongPathEffect should maintain initial angle of the component

[ivanfemia]

Description

See #2833

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.

Related Issues

Closes #2833

[spydon]

I don't think this is correct, since followAngle is true, it should be following the angle of the effect, and not be affected by what its current angle is?

[ivanfemia]

Well the problem is with the preexisting angle of the component, in the current release this is always initialized to the tangent. It should consider the angle of the component itself. Please have a look to the test code in the issue #2833.

(Example) I want a Rect to be 45 degrees turned (rhombus) and then use the vertex as the head to follow the path, currently the Rect is always following the path using one of the sides. In the example linked I used a Polygon with 3 vertex.

[spydon]

Then you should be using nativeAngle to set that, not angle.

[ivanfemia]

Sounds good, we can close this as intended behaviour

[ivanfemia]

@spydon Coding style preference

      (target as AngleProvider).angle = (target is PositionComponent)
          ? -start.angle + (target as PositionComponent).nativeAngle
          : -start.angle;

instead of

(target as AngleProvider).angle = _lastAngle = -start.angle;
(target as AngleProvider).angle += (target is PositionComponent)
          ? (target as PositionComponent).nativeAngle
          : 0;

[spydon]

@spydon Coding style preference

I think it is even clearer to read it if you separate them and just do:

final _target = target;
(_target as AngleProvider).angle = -start.angle;
if(_target is PositionComponent) {
  _target.angle += _target.nativeAngle;
}

[spydon]

Lgtm, only a variable name change needed I think!