Syntriax.Engine/Engine.Physics2D/Primitives/Circle.cs

using Syntriax.Engine.Core;
using Syntriax.Engine.Core.Abstract;

namespace Syntriax.Engine.Physics2D.Primitives;

[System.Diagnostics.DebuggerDisplay("Center: {Center.ToString(), nq}, Radius: {Radius}")]
public readonly struct Circle(Vector2D Center, float Radius)
{
    public static readonly Circle UnitCircle = new(Vector2D.Zero, 1f);

    public readonly Vector2D Center { get; init; } = Center;
    public readonly float Radius { get; init; } = Radius;

    public readonly float RadiusSquared => Radius * Radius;
    public readonly float Diameter => 2f * Radius;

    public static Circle SetCenter(Circle circle, Vector2D center) => new(center, circle.Radius);
    public static Circle SetRadius(Circle circle, float radius) => new(circle.Center, radius);

    public static Circle Displace(Circle circle, Vector2D displaceVector) => new(circle.Center + displaceVector, circle.Radius);

    public static Projection Project(Circle circle, Vector2D projectionVector)
    {
        float projectedCenter = circle.Center.Dot(projectionVector);
        return new(projectedCenter - circle.Radius, projectedCenter + circle.Radius);
    }

    public static Circle TransformCircle(ITransform transform, Circle circle)
        => new(transform.TransformVector2D(circle.Center), circle.Radius * transform.Scale.Magnitude);

    public static bool ApproximatelyEquals(Circle left, Circle right)
        => left.Center.ApproximatelyEquals(right.Center) && left.Radius.ApproximatelyEquals(right.Radius);
}

public static class CircleExtensions
{
    public static Circle SetCenter(this Circle circle, Vector2D center) => Circle.SetCenter(circle, center);
    public static Circle SetRadius(this Circle circle, float radius) => Circle.SetRadius(circle, radius);

    public static Circle Displace(this Circle circle, Vector2D displaceVector) => Circle.Displace(circle, displaceVector);

    public static Projection ToProjection(this Circle circle, Vector2D projectionVector) => Circle.Project(circle, projectionVector);

    public static Circle TransformCircle(this ITransform transform, Circle circle) => Circle.TransformCircle(transform, circle);

    public static bool ApproximatelyEquals(this Circle left, Circle right) => Circle.ApproximatelyEquals(left, right);
}