２D線分計算Class

線分と線分の交差判定や交差点、線分と点との最短距離、外積と法線を求める等の２Ｄでよく使う処理をまとめたClass

ClassLine.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

//線分class
public class ClassLine
{
    public Vector2 p1;//開始点
    public Vector2 p2;//終了点

    //線分コンストラクタ
    public ClassLine(Vector2 p1, Vector2 p2)
    {
        this.p1 = p1;
        this.p2 = p2;
    }
    //複製
    public ClassLine Clone()
    {
        return new ClassLine(p1, p2);
    }
    //ベクトル
    public Vector2 v
    {
        get { return p2 - p1; }
    }
    //2点間の距離
    public float distance
    {
        get { return Vector2.Distance(p1, p2); }
    }
    //外積
    public float cross(Vector2 p1, Vector2 p2)
    {
        return p1.x * p2.y - p2.x * p1.y;
    }
    //平行
    public bool isParallel(ClassLine line)
    {
        return cross(v, line.v) <= Vector2.kEpsilon;
    }
    //法線
    public Vector2 normal
    {
        get
        {
            return Vector2.Perpendicular(v);
        }
    }
    //最近点
    public Vector2 nearestPoint(Vector2 point)
    {
        Vector2 v1 = point - p1;
        float dot = Vector3.Dot(v, v1);

        Vector2 p = p1 + v * dot / v.sqrMagnitude;
        if (Vector2.Dot(p - p1, v) < 0) { p = p1; }
        else if (Vector2.Distance(p1, p) > distance) { p = p2; }

        return p;
    }
    //線分との交差判定
    public bool isCross(ClassLine line)
    {
        Vector2 v1 = p1 - line.p1;
        Vector2 v2 = p2 - line.p1;
        Vector2 v3 = line.p1 - p1;
        Vector2 v4 = line.p2 - p1;
        return cross(line.v, v1) * cross(line.v, v2) < 0 && cross(v, v3) * cross(v, v4) < 0;
    }
    //線分との交差点
    public Vector2 crossPoint(ClassLine line)
    {
        Vector2 v1 = line.p1 - p1;
        float nume = cross(v1, line.v);
        float deno = cross(v, line.v);
        float t = 0;
        if (deno != 0)
        {
            t = nume / deno;
        }
        return p1 + v * t;
    }
    //点との最短距離
    public float distanceFromPoint(Vector2 point)
    {
        return Vector2.Distance(nearestPoint(point), point);
    }
}