using System.Collections; using System.Collections.Generic; using UnityEngine; public class LineCircleIntersect : MonoBehaviour { public Transform a; public Transform b; public Transform circleCenter; public float radius; public float crossRadius = 0.5f;//交点圆圈大小 void OnDrawGizmos() { if (a == null || b == null || circleCenter == null) return; //交点1 var intersect1 = default(Vector2); //交点2 var intersect2 = default(Vector2); var intersectCount = BetweenLineAndCircle(circleCenter.position, radius, a.position, b.position, out intersect1, out intersect2); if (intersectCount > 0) Gizmos.DrawWireSphere(intersect1, crossRadius); if (intersectCount > 1) Gizmos.DrawWireSphere(intersect2, crossRadius); Gizmos.DrawLine(a.position, b.position); Gizmos.DrawWireSphere(circleCenter.position, radius); } /// <summary> /// /// </summary> /// <param name="circleCenter"></param> /// <param name="circleRadius"></param> /// <param name="point1"></param> /// <param name="point2"></param> /// <param name="intersection1">交点1</param> /// <param name="intersection2">交点2</param> /// <returns></returns> int BetweenLineAndCircle(Vector2 circleCenter, float circleRadius, Vector2 point1, Vector2 point2, out Vector2 intersection1, out Vector2 intersection2) { float t; var dx = point2.x - point1.x; var dy = point2.y - point1.y; var a = dx * dx + dy * dy; var b = 2 * (dx * (point1.x - circleCenter.x) + dy * (point1.y - circleCenter.y)); var c = (point1.x - circleCenter.x) * (point1.x - circleCenter.x) + (point1.y - circleCenter.y) * (point1.y - circleCenter.y) - circleRadius * circleRadius; var determinate = b * b - 4 * a * c; if ((a <= 0.0000001) || (determinate < -0.0000001)) { //没有交点的情况 intersection1 = Vector2.zero; intersection2 = Vector2.zero; return 0; } if (determinate < 0.0000001 && determinate > -0.0000001) { //一个交点的情况 t = -b / (2 * a); intersection1 = new Vector2(point1.x + t * dx, point1.y + t * dy); intersection2 = Vector2.zero; return 1; } //两个交点的情况 t = ((-b + Mathf.Sqrt(determinate)) / (2 * a)); intersection1 = new Vector2(point1.x + t * dx, point1.y + t * dy); t = ((-b - Mathf.Sqrt(determinate)) / (2 * a)); intersection2 = new Vector2(point1.x + t * dx, point1.y + t * dy); return 2; } }