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RaycastHit.triangleIndex

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public int triangleIndex;

Description

The index of the triangle that was hit.

Triangle index is only valid if the collider that was hit is a MeshCollider.

// This script draws a debug line around mesh triangles
// as you move the mouse over them.
using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour { Camera cam;

void Start() { cam = GetComponent<Camera>(); }

void Update() { RaycastHit hit; if (!Physics.Raycast(cam.ScreenPointToRay(Input.mousePosition), out hit)) return;

MeshCollider meshCollider = hit.collider as MeshCollider; if (meshCollider == null || meshCollider.sharedMesh == null) return;

Mesh mesh = meshCollider.sharedMesh; Vector3[] vertices = mesh.vertices; int[] triangles = mesh.triangles; Vector3 p0 = vertices[triangles[hit.triangleIndex * 3 + 0]]; Vector3 p1 = vertices[triangles[hit.triangleIndex * 3 + 1]]; Vector3 p2 = vertices[triangles[hit.triangleIndex * 3 + 2]]; Transform hitTransform = hit.collider.transform; p0 = hitTransform.TransformPoint(p0); p1 = hitTransform.TransformPoint(p1); p2 = hitTransform.TransformPoint(p2); Debug.DrawLine(p0, p1); Debug.DrawLine(p1, p2); Debug.DrawLine(p2, p0); } }

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