Add regular constructors to PolygonComponent and PolygonHitbox

[TRI99ERED]

Problem to solve

This proposal aims to improve the classes creating polygons with a direct way to create a regular polygon. Especially relevant for PolygonHitbox, because it only works normally with convex polygons and regular polygons are convex.

Proposal

Feature Request: Add PolygonComponent.regular and PolygonHitbox.regular constructors

Summary

Add convenience constructors to create regular convex polygons (e.g., triangles, pentagons, hexagons) by specifying the number of sides and radius, instead of manually providing a list of vertices.

Use Case

Currently, creating a regular polygon (like a hexagon or octagon) requires manually calculating and providing all vertices:

// Current approach - verbose
final vertices = List.generate(6, (i) {
  final angle = 2 * pi * i / 6;
  return Vector2(100 * cos(angle), 100 * sin(angle));
});
PolygonComponent(vertices);

This feature would allow a much simpler API:

// Proposed API
PolygonComponent.regular(sides: 6, radius: 100);
PolygonHitbox.regular(sides: 6, radius: 100);

Proposed API

PolygonComponent.regular

PolygonComponent.regular({
  required int sides,
  required double radius,
  Vector2? position,
  Vector2? size,
  Vector2? scale,
  double? angle,
  Anchor? anchor,
  Iterable<Component>? children,
  int? priority,
  Paint? paint,
  List<Paint>? paintLayers,
  ComponentKey? key,
  bool? shrinkToBounds,
})

• sides: Number of sides (must be > 2)
• radius: Distance from center to each vertex
• shrinkToBounds: Defaults to true if size is not provided

PolygonHitbox.regular

PolygonHitbox.regular({
  required int sides,
  required double radius,
  Vector2? position,
  double? angle,
  Anchor? anchor,
  bool isSolid = false,
  CollisionType collisionType = CollisionType.active,
})

Implementation Notes

The constructors should generate vertices using:

final vertices = List.generate(sides, (i) {
  final angle = 2 * pi * i / sides;
  return Vector2(radius * cos(angle), radius * sin(angle));
}, growable: false);

More information

This approach for creating convex polygons is currently adopted by a lot of projects. Among them Unreal Engine (in Draw Debug Regular Polygon), SFML (using CircleShape) and bevy engine (using RegularPolygon).

Other

• Are you interested in working on a PR for this?

[spydon]

I like the idea. I think the naming needs to better convey what it does though regular doesn't feel that clear.
I'll assign you to the issue since you've checked that you want to work on this. :)