MoonTools.Bonk/Bonk/Shapes/Simplex.cs

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using System.Linq;
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using System.Collections.Generic;
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using System.Numerics;
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using MoonTools.Core.Structs;
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using MoreLinq;
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namespace MoonTools.Core.Bonk
{
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/// <summary>
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/// A simplex is a shape with up to n - 2 vertices in the nth dimension.
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/// </summary>
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public struct Simplex2D : IShape2D
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{
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Vector2 a;
Vector2? b;
Vector2? c;
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public Vector2 A => a;
public Vector2? B => b;
public Vector2? C => c;
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public bool ZeroSimplex { get { return !b.HasValue && !c.HasValue; } }
public bool OneSimplex { get { return b.HasValue && !c.HasValue; } }
public bool TwoSimplex { get { return b.HasValue && c.HasValue; } }
public int Count => TwoSimplex ? 3 : (OneSimplex ? 2 : 1);
public Simplex2D(Vector2 a)
{
this.a = a;
this.b = null;
this.c = null;
}
public Simplex2D(Vector2 a, Vector2 b)
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{
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this.a = a;
this.b = b;
this.c = null;
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}
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public Simplex2D(Vector2 a, Vector2 b, Vector2 c)
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{
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this.a = a;
this.b = b;
this.c = c;
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}
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public IEnumerable<Position2D> Vertices
{
get
{
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yield return (Position2D)a;
if (b.HasValue) { yield return (Position2D)b; }
if (c.HasValue) { yield return (Position2D)c; }
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}
}
public AABB AABB(Transform2D transform)
{
return Bonk.AABB.FromTransformedVertices(Vertices, transform);
}
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public Vector2 Support(Vector2 direction)
{
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return Vertices.MaxBy(vertex => Vector2.Dot(vertex, direction)).First();
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}
public Vector2 Support(Vector2 direction, Transform2D transform)
{
return Vector2.Transform(Support(direction), transform.TransformMatrix);
}
public override bool Equals(object obj)
{
if (obj is IShape2D other)
{
return Equals(other);
}
return false;
}
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public bool Equals(IShape2D other)
{
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if (other is Simplex2D otherSimplex)
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{
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if (Count != otherSimplex.Count) { return false; }
return Vertices.Intersect(otherSimplex.Vertices).Count() == Count;
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}
return false;
}
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public override int GetHashCode()
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{
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var hashCode = -495772172;
hashCode = hashCode * -1521134295 + EqualityComparer<Vector2>.Default.GetHashCode(a);
hashCode = hashCode * -1521134295 + EqualityComparer<Vector2?>.Default.GetHashCode(b);
hashCode = hashCode * -1521134295 + EqualityComparer<Vector2?>.Default.GetHashCode(c);
hashCode = hashCode * -1521134295 + ZeroSimplex.GetHashCode();
hashCode = hashCode * -1521134295 + OneSimplex.GetHashCode();
hashCode = hashCode * -1521134295 + TwoSimplex.GetHashCode();
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hashCode = hashCode * -1521134295 + EqualityComparer<IEnumerable<Position2D>>.Default.GetHashCode(Vertices);
return hashCode;
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}
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public static bool operator ==(Simplex2D a, Simplex2D b)
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{
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return a.Equals(b);
}
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public static bool operator !=(Simplex2D a, Simplex2D b)
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{
return !(a == b);
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}
}
}