*

Assets/Scenes/RaycastMath.cs

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+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+using static OpticalSurface2D;
+
+public class RaycastMath
+{
+    public struct RaycastResult2D {
+        public Vector2 Point;
+        public Vector2 Normal;
+    }
+
+    public static bool RaycastCircle(Ray2D ray, float radius, ref RaycastResult2D result) {
+        var vToCircleCenter = Vector2.zero - ray.origin;
+
+        bool isInsideCircle = vToCircleCenter.magnitude < radius;
+
+        var d = Vector2.Dot(vToCircleCenter, ray.direction.normalized);
+
+
+        if(d < 0 && ray.origin.magnitude > radius) {
+            return false;
+        }
+
+        var p = ray.origin + ray.direction.normalized * d;
+
+        var v = Vector2.zero - p;
+
+        var rayCenterDistance = v.magnitude;
+        if (rayCenterDistance > radius) {
+            return false;
+        } else if (rayCenterDistance == radius) {
+            result.Point = p;
+            result.Normal = p.normalized;
+        } else {
+
+            float m = Mathf.Sqrt(radius * radius - rayCenterDistance * rayCenterDistance);
+
+            if (isInsideCircle) {
+                result.Point = p + ray.direction.normalized * m;
+                result.Normal = result.Point.normalized;
+            } else {
+                result.Point = p - ray.direction.normalized * m;
+                result.Normal = result.Point.normalized;
+            }
+        }
+        return true;
+    }
+
+
+    public static bool RayLineIntersection(Vector2 rayOrigin, Vector2 rayDirection, Vector2 lineOrigin, Vector2 lineDirection, ref Vector2 hitPoint) {
+        Vector2 rayTangent = new Vector2(-rayDirection.y, rayDirection.x);
+
+        float distanceToLine = Vector2.Dot(lineOrigin - rayOrigin, rayTangent);
+        float origin2ExtensionDistance = distanceToLine / Vector2.Dot(-rayTangent, lineDirection);
+        hitPoint = origin2ExtensionDistance * lineDirection + lineOrigin;
+
+        return Vector2.Dot(hitPoint - rayOrigin, rayDirection) > 0.0f;
+    }
+
+    public static bool RayLineSegmentIntersection(Vector2 rayOrigin, Vector2 rayDirection, Vector2 lineOrigin, Vector2 lineP2, ref Vector2 hitPoint) {
+        Vector2 rayTangent = new Vector2(-rayDirection.y, rayDirection.x);
+
+        Vector2 lineDirection = lineP2 - lineOrigin;
+
+
+        float distanceToLine = Vector2.Dot(lineOrigin - rayOrigin, rayTangent);
+        float origin2ExtensionDistance = distanceToLine / Vector2.Dot(-rayTangent, lineDirection);
+        hitPoint = origin2ExtensionDistance * lineDirection + lineOrigin;
+
+        if (Vector2.Dot(hitPoint - rayOrigin, rayDirection) < 0.0f) {
+            return false;
+        }
+
+        var d = Vector2.Dot(hitPoint - lineOrigin, lineDirection.normalized);
+        if (d < 0.0f || d > lineDirection.magnitude) {
+            return false;
+        }
+
+        return true;
+    }
+}