MoonTools.Bonk/Bonk/Shapes/Polygon.cs

75 lines
2.2 KiB
C#

using System.Linq;
using System;
using System.Collections.Generic;
using System.Numerics;
using Collections.Pooled;
using MoonTools.Core.Structs;
using MoreLinq;
namespace MoonTools.Core.Bonk
{
/// <summary>
/// A Shape defined by an arbitrary collection of vertices. WARNING: Polygon must use an Array internally and therefore will create GC pressure.
/// </summary>
public struct Polygon : IShape2D, IEquatable<IShape2D>
{
private PooledSet<Position2D> vertices;
public IEnumerable<Position2D> Vertices { get { return vertices == null ? Enumerable.Empty<Position2D>() : vertices; } }
// vertices are local to the origin
public Polygon(params Position2D[] vertices)
{
this.vertices = new PooledSet<Position2D>(vertices, ClearMode.Always);
}
public Vector2 Support(Vector2 direction, Transform2D transform)
{
return Vertices.Select(vertex => Vector2.Transform(vertex, transform.TransformMatrix)).MaxBy(transformed => Vector2.Dot(transformed, direction)).First();
}
public AABB AABB(Transform2D Transform2D)
{
return Bonk.AABB.FromTransformedVertices(Vertices, Transform2D);
}
public override bool Equals(object obj)
{
if (obj is IShape2D other)
{
return Equals(other);
}
return false;
}
public bool Equals(IShape2D other)
{
if (other is Polygon otherPolygon)
{
return vertices.SetEquals(otherPolygon.vertices);
}
return false;
}
public override int GetHashCode()
{
var hashCode = -1404792980;
hashCode = hashCode * -1521134295 + EqualityComparer<PooledSet<Position2D>>.Default.GetHashCode(vertices);
hashCode = hashCode * -1521134295 + EqualityComparer<IEnumerable<Position2D>>.Default.GetHashCode(Vertices);
return hashCode;
}
public static bool operator ==(Polygon a, Polygon b)
{
return a.Equals(b);
}
public static bool operator !=(Polygon a, Polygon b)
{
return !(a == b);
}
}
}