2023-12-07 10:55:49 +03:00
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using System;
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using System.Collections.Generic;
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using System.Diagnostics.CodeAnalysis;
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using Microsoft.Xna.Framework;
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namespace Syntriax.Engine.Physics2D.Primitives;
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public record Line(Vector2 From, Vector2 To)
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{
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public Vector2 Direction => Vector2.Normalize(To - From);
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public float Length => (From - To).Length();
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public float LengthSquared => (From - To).LengthSquared();
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public LineEquation LineEquation
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{
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get
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{
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Vector2 slopeVector = To - From;
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float slope = slopeVector.Y / slopeVector.X;
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float yOffset = From.Y - (slope * From.X);
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return new LineEquation(slope, yOffset);
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}
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}
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public bool Intersects(Vector2 point)
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=> Resolve(point.X).ApproximatelyEquals(point);
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public float GetT(Vector2 point)
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{
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float fromX = MathF.Abs(From.X);
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float toX = MathF.Abs(To.X);
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float pointX = MathF.Abs(point.X);
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float min = MathF.Min(fromX, toX);
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float max = MathF.Max(fromX, toX) - min;
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pointX -= min;
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return pointX / max;
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}
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public bool Exist(List<Vector2> vertices)
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{
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for (int i = 0; i < vertices.Count - 1; i++)
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{
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Vector2 vertexCurrent = vertices[i];
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Vector2 vertexNext = vertices[i];
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if (From == vertexCurrent && To == vertexNext) return true;
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if (From == vertexNext && To == vertexCurrent) return true;
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}
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Vector2 vertexFirst = vertices[0];
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Vector2 vertexLast = vertices[^1];
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if (From == vertexFirst && To == vertexLast) return true;
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if (From == vertexLast && To == vertexFirst) return true;
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return false;
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}
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public float IntersectionParameterT(Line other)
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=> ((other.From.X - From.X) * (To.Y - From.Y) - (other.From.Y - From.Y) * (To.X - From.X)) /
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((other.To.Y - other.From.Y) * (To.X - From.X) - (other.To.X - other.From.X) * (To.Y - From.Y));
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public Vector2 Resolve(float x)
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=> new Vector2(x, LineEquation.Resolve(x));
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public Vector2 ClosestPointTo(Vector2 point)
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{
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// Convert edge points to vectors
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var edgeVector = new Vector2(To.X - From.X, To.Y - From.Y);
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var pointVector = new Vector2(point.X - From.X, point.Y - From.Y);
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// Calculate the projection of pointVector onto edgeVector
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float t = (pointVector.X * edgeVector.X + pointVector.Y * edgeVector.Y) / (edgeVector.X * edgeVector.X + edgeVector.Y * edgeVector.Y);
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// Clamp t to the range [0, 1] to ensure the closest point is on the edge
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t = Math.Max(0, Math.Min(1, t));
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// Calculate the closest point on the edge
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float closestX = From.X + t * edgeVector.X;
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float closestY = From.Y + t * edgeVector.Y;
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return new Vector2((float)closestX, (float)closestY);
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}
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public Vector2 IntersectionPoint(Line other)
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=> Vector2.Lerp(From, To, IntersectionParameterT(other));
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public bool Intersects(Line other)
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{
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int o1 = PhysicsMath.Orientation(From, To, other.From);
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int o2 = PhysicsMath.Orientation(From, To, other.To);
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int o3 = PhysicsMath.Orientation(other.From, other.To, From);
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int o4 = PhysicsMath.Orientation(other.From, other.To, To);
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if (o1 != o2 && o3 != o4)
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return true;
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if (o1 == 0 && PhysicsMath.OnSegment(From, other.From, To)) return true;
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if (o2 == 0 && PhysicsMath.OnSegment(From, other.To, To)) return true;
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if (o3 == 0 && PhysicsMath.OnSegment(other.From, From, other.To)) return true;
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if (o4 == 0 && PhysicsMath.OnSegment(other.From, To, other.To)) return true;
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return false;
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}
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public bool Intersects(Line other, [NotNullWhen(returnValue: true)] out Vector2? point)
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{
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point = null;
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bool result = Intersects(other);
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if (result)
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point = IntersectionPoint(other);
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return result;
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}
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2023-12-07 11:14:18 +03:00
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public bool ApproximatelyEquals(Line other)
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=> From.ApproximatelyEquals(other.From) && To.ApproximatelyEquals(other.To);
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2023-12-07 10:55:49 +03:00
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}
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