109 lines
5.3 KiB
C#
109 lines
5.3 KiB
C#
using System;
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namespace Engine.Core;
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/// <summary>
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/// Represents an infinite ray in 2D space.
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/// </summary>
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/// <param name="Origin">The <see cref="Vector2D"/> in 2D space where the ray starts from.</param>
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/// <param name="Direction">Normalized <see cref="Vector2D"/> indicating the ray's is direction.</param>
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public readonly struct Ray2D(Vector2D Origin, Vector2D Direction) : IEquatable<Ray2D>
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{
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/// <summary>
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/// The starting point of the <see cref="Ray2D"/>.
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/// </summary>
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public readonly Vector2D Origin = Origin;
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/// <summary>
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/// The direction in which the <see cref="Ray2D"/> points. Should be a normalized vector.
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/// </summary>
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public readonly Vector2D Direction = Direction;
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/// <summary>
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/// Gets a <see cref="Ray2D"/> with the same origin but with the direction reversed.
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/// </summary>
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public readonly Ray2D Reversed => new(Origin, -Direction);
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public static bool operator ==(Ray2D left, Ray2D right) => left.Origin == right.Origin && left.Direction == right.Direction;
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public static bool operator !=(Ray2D left, Ray2D right) => left.Origin != right.Origin || left.Direction != right.Direction;
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public static implicit operator Ray2D(Line2D line) => new(line.From, line.From.FromTo(line.To).Normalized);
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/// <summary>
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/// Constructs a <see cref="Line2D"/> from a <see cref="Ray2D"/>, extending from its origin in the <see cref="Ray2D"/>'s direction for a given distance.
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/// </summary>
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/// <param name="ray">The source <see cref="Ray2D"/>.</param>
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/// <param name="distance">The length of the line segment to create from the <see cref="Ray2D"/>.</param>
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/// <returns>A <see cref="Line2D"/> representing the segment of the <see cref="Ray2D"/>.</returns>
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public static Line2D GetLine(Ray2D ray, float distance)
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=> new(ray.Origin, ray.Origin + ray.Direction * distance);
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/// <summary>
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/// Evaluates the point on the <see cref="Ray2D"/> at a specified distance from its origin.
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/// </summary>
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/// <param name="ray">The <see cref="Ray2D"/> to evaluate.</param>
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/// <param name="distanceFromOrigin">The distance from the origin along the <see cref="Ray2D"/>'s direction.</param>
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/// <returns>A <see cref="Vector2D"/> representing the point at the given distance on the <see cref="Ray2D"/>.</returns>
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public static Vector2D Evaluate(Ray2D ray, float distanceFromOrigin)
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=> ray.Origin + ray.Direction * distanceFromOrigin;
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/// <summary>
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/// Calculates the closest point on the <see cref="Ray2D"/> to the specified point.
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/// </summary>
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public static Vector2D ClosestPointTo(Ray2D ray, Vector2D point)
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{
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Vector2D originToPoint = ray.Origin.FromTo(point);
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float dot = ray.Direction.Dot(originToPoint);
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return ray.Origin + ray.Direction * dot;
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}
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/// <summary>
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/// Checks if two <see cref="Ray2D"/>s are approximately equal within a specified epsilon range.
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/// </summary>
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/// <param name="left">The first <see cref="Ray2D"/>.</param>
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/// <param name="right">The second <see cref="Ray2D"/>.</param>
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/// <param name="epsilon">The epsilon range.</param>
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/// <returns><see cref="true"/> if the <see cref="Ray2D"/>s are approximately equal; otherwise, <see cref="false"/>.</returns>
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public static bool ApproximatelyEquals(Ray2D left, Ray2D right, float epsilon = float.Epsilon)
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=> left.Origin.ApproximatelyEquals(right.Origin, epsilon) && left.Direction.ApproximatelyEquals(right.Direction, epsilon);
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/// <summary>
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/// Determines whether the specified object is equal to the current <see cref="Ray2D"/>.
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/// </summary>
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/// <param name="obj">The object to compare with the current <see cref="Ray2D"/>.</param>
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/// <returns><see cref="true"/> if the specified object is equal to the current <see cref="Ray2D"/>; otherwise, <see cref="false"/>.</returns>
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public override bool Equals(object? obj) => obj is Ray2D ray2D && this == ray2D;
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public bool Equals(Ray2D other) => this == other;
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/// <summary>
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/// Generates a hash code for the <see cref="Ray2D"/>.
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/// </summary>
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/// <returns>A hash code for the <see cref="Ray2D"/>.</returns>
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public override int GetHashCode() => System.HashCode.Combine(Origin, Direction);
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/// <summary>
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/// Converts the <see cref="Ray2D"/> to its string representation.
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/// </summary>
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/// <returns>A string representation of the <see cref="Ray2D"/>.</returns>
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public override string ToString() => $"{nameof(Ray2D)}({Origin}, {Direction})";
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}
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/// <summary>
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/// Provides extension methods for the <see cref="Ray2D"/> struct.
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/// </summary>
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public static class Ray2DExtensions
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{
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/// <inheritdoc cref="Ray2D.GetLine(Ray2D, float) />
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public static Line2D ToLine(this Ray2D ray, float distance) => Ray2D.GetLine(ray, distance);
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/// <inheritdoc cref="Ray2D.Evaluate(Ray2D, float) />
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public static Vector2D Evaluate(this Ray2D ray, float distanceFromOrigin) => Ray2D.Evaluate(ray, distanceFromOrigin);
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/// <inheritdoc cref="Ray2D.ClosestPointTo(Ray2D, Vector2D) />
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public static Vector2D ClosestPointTo(this Ray2D ray, Vector2D point) => Ray2D.ClosestPointTo(ray, point);
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/// <inheritdoc cref="Ray2D.ApproximatelyEquals(Ray2D, Ray2D, float)" />
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public static bool ApproximatelyEquals(this Ray2D left, Ray2D right, float epsilon = float.Epsilon) => Ray2D.ApproximatelyEquals(left, right, epsilon);
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}
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