79 lines
3.7 KiB
C#
79 lines
3.7 KiB
C#
using System;
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namespace Engine.Core;
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[System.Diagnostics.DebuggerDisplay("A: {A.ToString(), nq}, B: {B.ToString(), nq}, B: {C.ToString(), nq}")]
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public readonly struct Triangle(Vector2D A, Vector2D B, Vector2D C) : IEquatable<Triangle>
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{
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public readonly Vector2D A { get; init; } = A;
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public readonly Vector2D B { get; init; } = B;
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public readonly Vector2D C { get; init; } = C;
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public static bool operator ==(Triangle left, Triangle right) => left.A == right.A && left.B == right.B && left.C == right.C;
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public static bool operator !=(Triangle left, Triangle right) => left.A != right.A || left.B != right.B || left.C != right.C;
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public readonly float Area
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=> .5f * Math.Abs(
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A.X * (B.Y - C.Y) +
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B.X * (C.Y - A.Y) +
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C.X * (A.Y - B.Y)
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);
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public static Circle GetCircumCircle(Triangle triangle)
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{
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Vector2D midAB = (triangle.A + triangle.B) / 2f;
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Vector2D midBC = (triangle.B + triangle.C) / 2f;
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float slopeAB = (triangle.B.Y - triangle.A.Y) / (triangle.B.X - triangle.A.X);
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float slopeBC = (triangle.C.Y - triangle.B.Y) / (triangle.C.X - triangle.B.X);
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Vector2D center;
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if (Math.Abs(slopeAB - slopeBC) > float.Epsilon)
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{
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float x = (slopeAB * slopeBC * (triangle.A.Y - triangle.C.Y) + slopeBC * (triangle.A.X + triangle.B.X) - slopeAB * (triangle.B.X + triangle.C.X)) / (2f * (slopeBC - slopeAB));
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float y = -(x - (triangle.A.X + triangle.B.X) / 2f) / slopeAB + (triangle.A.Y + triangle.B.Y) / 2f;
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center = new Vector2D(x, y);
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}
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else
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center = (midAB + midBC) * .5f;
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return new(center, Vector2D.Distance(center, triangle.A));
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}
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/// <summary>
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/// Determines whether two <see cref="Triangle"/>s are approximately equal.
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/// </summary>
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/// <param name="left">The first <see cref="Triangle"/> to compare.</param>
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/// <param name="right">The second <see cref="Triangle"/> to compare.</param>
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/// <param name="epsilon">The epsilon range.</param>
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/// <returns><c>true</c> if the <see cref="Triangle"/>s are approximately equal; otherwise, <c>false</c>.</returns>
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public static bool ApproximatelyEquals(Triangle left, Triangle right, float epsilon = float.Epsilon)
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=> left.A.ApproximatelyEquals(right.A, epsilon) && left.B.ApproximatelyEquals(right.B, epsilon) && left.C.ApproximatelyEquals(right.C, epsilon);
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/// <summary>
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/// Determines whether the specified object is equal to the current <see cref="Triangle"/>.
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/// </summary>
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/// <param name="obj">The object to compare with the current <see cref="Triangle"/>.</param>
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/// <returns><see cref="true"/> if the specified object is equal to the current <see cref="Triangle"/>; otherwise, <see cref="false"/>.</returns>
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public override bool Equals(object? obj) => obj is Triangle triangle && this == triangle;
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public bool Equals(Triangle other) => this == other;
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/// <summary>
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/// Generates a hash code for the <see cref="Triangle"/>.
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/// </summary>
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/// <returns>A hash code for the <see cref="Triangle"/>.</returns>
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public override int GetHashCode() => System.HashCode.Combine(A, B, C);
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/// <summary>
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/// Converts the <see cref="Triangle"/> to its string representation.
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/// </summary>
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/// <returns>A string representation of the <see cref="Triangle"/>.</returns>
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public override string ToString() => $"{nameof(Triangle)}({A}, {B}, {C})";
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}
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public static class TriangleExtensions
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{
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/// <inheritdoc cref="Triangle.ApproximatelyEquals(Triangle, Triangle, float)" />
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public static bool ApproximatelyEquals(this Triangle left, Triangle right, float epsilon = float.Epsilon) => Triangle.ApproximatelyEquals(left, right, epsilon);
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}
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