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refactor: moved 2D primitives from Physics2D to Core

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Syntriax
2025-03-17 21:57:09 +03:00
parent 9ecf0b900f
commit 183966d239
17 changed files with 408 additions and 413 deletions
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Engine.Core/Primitives/Line2D.cs Normal file
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using System;
using System.Diagnostics.CodeAnalysis;
namespace Syntriax.Engine.Core;
/// <summary>
/// Represents a 2D line segment defined by two endpoints.
/// </summary>
/// <param name="from">The starting point of the <see cref="Line2D"/> segment.</param>
/// <param name="to">The ending point of the <see cref="Line2D"/> segment.</param>
/// <remarks>
/// Initializes a new instance of the <see cref="Line2D"/> struct with the specified endpoints.
/// </remarks>
[System.Diagnostics.DebuggerDisplay("From: {From.ToString(),nq}, To: {To.ToString(),nq}, Direction: {Direction.ToString(),nq}, Length: {Length}")]
public readonly struct Line2D(Vector2D from, Vector2D to)
{
/// <summary>
/// The starting point of the <see cref="Line2D"/> segment.
/// </summary>
public readonly Vector2D From = from;
/// <summary>
/// The ending point of the <see cref="Line2D"/> segment.
/// </summary>
public readonly Vector2D To = to;
/// <summary>
/// The reversed <see cref="Line2D"/> segment.
/// </summary>
public readonly Line2D Reversed => new(To, From);
/// <summary>
/// The normalized direction <see cref="Vector2D"/> of the <see cref="Line2D"/> segment.
/// </summary>
public readonly Vector2D Direction => From.FromTo(To).Normalize();
/// <summary>
/// The length of the <see cref="Line2D"/> segment.
/// </summary>
public readonly float Length => From.FromTo(To).Length();
/// <summary>
/// The squared length of the <see cref="Line2D"/> segment.
/// </summary>
public readonly float LengthSquared => From.FromTo(To).LengthSquared();
/// <summary>
/// The equation of the <see cref="Line2D"/> defined by this <see cref="Line2D"/> segment.
/// </summary>
public static Line2DEquation GetLineEquation(Line2D line)
{
Vector2D slopeVector = line.From.FromTo(line.To);
float slope = slopeVector.Y / slopeVector.X;
float yOffset = line.From.Y - (slope * line.From.X);
return new Line2DEquation(slope, yOffset);
}
/// <summary>
/// Determines whether the specified <see cref="Vector2D"/> lies on the <see cref="Line2D"/>.
/// </summary>
public static bool Intersects(Line2D line, Vector2D point)
=> Line2DEquation.Resolve(GetLineEquation(line), point.X).ApproximatelyEquals(point.Y);
/// <summary>
/// Calculates the parameter 't' representing the point's position on the <see cref="Line2D"/> segment.
/// </summary>
public static float GetT(Line2D line, Vector2D point)
{
float fromX = MathF.Abs(line.From.X);
float toX = MathF.Abs(line.To.X);
float pointX = MathF.Abs(point.X);
float min = MathF.Min(fromX, toX);
float max = MathF.Max(fromX, toX) - min;
pointX -= min;
float t = pointX / max;
// FIXME
// I don't even know, apparently whatever I wrote up there doesn't take into account of the direction of the line
// Which... I can see how, but I am also not sure how I can make it take into account. Or actually I'm for some reason
// too unmotivated to find a solution. Future me, find a better way if possible, please.
if (!Lerp(line, t).ApproximatelyEquals(point))
return 1f - t;
return t;
}
/// <summary>
/// Checks if the <see cref="Line2D"/> segment intersects with another <see cref="Line2D"/> segment.
/// </summary>
public static bool Intersects(Line2D left, Line2D right)
{
int o1 = Vector2D.Orientation(left.From, left.To, right.From);
int o2 = Vector2D.Orientation(left.From, left.To, right.To);
int o3 = Vector2D.Orientation(right.From, right.To, left.From);
int o4 = Vector2D.Orientation(right.From, right.To, left.To);
if (o1 != o2 && o3 != o4)
return true;
if (o1 == 0 && OnSegment(left, right.From)) return true;
if (o2 == 0 && OnSegment(left, right.To)) return true;
if (o3 == 0 && OnSegment(right, left.From)) return true;
if (o4 == 0 && OnSegment(right, left.To)) return true;
return false;
}
/// <summary>
/// Checks if the point lies within the <see cref="Line2D"/> segment.
/// </summary>
public static bool OnSegment(Line2D line, Vector2D point)
{
if (point.X <= MathF.Max(line.From.X, line.To.X) && point.X >= MathF.Min(line.From.X, line.To.X) &&
point.Y <= MathF.Max(line.From.Y, line.To.Y) && point.Y >= MathF.Min(line.From.Y, line.To.Y))
return true;
return false;
}
/// <summary>
/// Determines whether two <see cref="Line2D"/> segments intersect.
/// </summary>
public static bool Intersects(Line2D left, Line2D right, [NotNullWhen(returnValue: true)] out Vector2D? point)
{
point = null;
bool result = Intersects(left, right);
if (result)
point = IntersectionPoint(left, right);
return result;
}
/// <summary>
/// Finds the point of intersection between two <see cref="Line2D"/> segments.
/// </summary>
public static Vector2D IntersectionPoint(Line2D left, Line2D right)
=> Vector2D.Lerp(left.From, left.To, IntersectionParameterT(left, right));
/// <summary>
/// Calculates the parameter 't' representing the intersection point's position on the <see cref="Line2D"/> segment.
/// </summary>
public static float IntersectionParameterT(Line2D left, Line2D right)
{
float numerator = (left.From.X - right.From.X) * (right.From.Y - right.To.Y) - (left.From.Y - right.From.Y) * (right.From.X - right.To.X);
float denominator = (left.From.X - left.To.X) * (right.From.Y - right.To.Y) - (left.From.Y - left.To.Y) * (right.From.X - right.To.X);
// Lines are parallel
if (denominator == 0)
return float.NaN;
return numerator / denominator;
}
/// <summary>
/// Linearly interpolates between the two endpoints of the <see cref="Line2D"/> segment using parameter 't'.
/// </summary>
public static Vector2D Lerp(Line2D line, float t)
=> Vector2D.Lerp(line.From, line.To, t);
/// <summary>
/// Calculates the closest point on the <see cref="Line2D"/> segment to the specified point.
/// </summary>
public static Vector2D ClosestPointTo(Line2D line, Vector2D point)
{
Vector2D edgeVector = line.From.FromTo(line.To);
Vector2D pointVector = point - line.From;
float t = (pointVector.X * edgeVector.X + pointVector.Y * edgeVector.Y) / (edgeVector.X * edgeVector.X + edgeVector.Y * edgeVector.Y);
t = MathF.Max(0, MathF.Min(1, t));
float closestX = line.From.X + t * edgeVector.X;
float closestY = line.From.Y + t * edgeVector.Y;
return new Vector2D((float)closestX, (float)closestY);
}
/// <summary>
/// Checks if two <see cref="Line2D"/> segments are approximately equal.
/// </summary>
public static bool ApproximatelyEquals(Line2D left, Line2D right)
=> left.From.ApproximatelyEquals(right.From) && left.To.ApproximatelyEquals(right.To);
}
/// <summary>
/// Provides extension methods for the Line struct.
/// </summary>
public static class Line2DExtensions
{
/// <summary>
/// Linearly interpolates between the two endpoints of the <see cref="Line2D"/> segment using parameter 't'.
/// </summary>
public static Vector2D Lerp(this Line2D line, float t) => Line2D.Lerp(line, t);
/// <summary>
/// The equation of the <see cref="Line2D"/> defined by this <see cref="Line2D"/> segment.
/// </summary>
public static Line2DEquation ToLineEquation(this Line2D line) => Line2D.GetLineEquation(line);
/// <summary>
/// Determines whether the specified <see cref="Vector2D"/> lies on the <see cref="Line2D"/>.
/// </summary>
public static bool Intersects(this Line2D line, Vector2D point) => Line2D.Intersects(line, point);
/// <summary>
/// Calculates the parameter 't' representing the point's position on the <see cref="Line2D"/> segment.
/// </summary>
public static float GetT(this Line2D line, Vector2D point) => Line2D.GetT(line, point);
/// <summary>
/// Checks if the <see cref="Line2D"/> segment intersects with another <see cref="Line2D"/> segment.
/// </summary>
public static bool Intersects(this Line2D left, Line2D right) => Line2D.Intersects(left, right);
/// <summary>
/// Determines whether two <see cref="Line2D"/> segments intersect.
/// </summary>
public static bool Intersects(this Line2D left, Line2D right, [NotNullWhen(returnValue: true)] out Vector2D? point) => Line2D.Intersects(left, right, out point);
/// <summary>
/// Checks if two <see cref="Line2D"/>s are approximately equal.
/// </summary>
public static bool ApproximatelyEquals(this Line2D left, Line2D right) => Line2D.ApproximatelyEquals(left, right);
}