RaycastHit.barycentricCoordinate

Description

The barycentric coordinate of the triangle we hit.

This lets you interpolate any of the vertex data along the 3 axes.

	// Attach this script to a camera and it will 
	// draw a debug line pointing outward from the normal 
	function Update () { 
	   // Only if we hit something, do we continue 
	   var hit : RaycastHit; 
	   if (!Physics.Raycast (Camera.main.ScreenPointToRay(Input.mousePosition), hit)) 
	      return; 

	   // Just in case, also make sure the collider also has a renderer 
	   // material and texture 
	   var meshCollider = hit.collider as MeshCollider; 
	   if (meshCollider == null || meshCollider.sharedMesh == null) 
	      return; 

	   var mesh : Mesh = meshCollider.sharedMesh; 
	   var normals = mesh.normals; 
	   var triangles = mesh.triangles; 

	   // Extract local space normals of the triangle we hit 
	   var n0 = normals[triangles[hit.triangleIndex * 3 + 0]]; 
	   var n1 = normals[triangles[hit.triangleIndex * 3 + 1]];    
	   var n2 = normals[triangles[hit.triangleIndex * 3 + 2]];    
	    
	   // interpolate using the barycentric coordinate of the hitpoint 
	   var baryCenter = hit.barycentricCoordinate; 

	   // Use barycentric coordinate to interpolate normal 
	   var interpolatedNormal = n0 * baryCenter.x + n1 * baryCenter.y + n2 * baryCenter.z; 
	   // normalize the interpolated normal 
	   interpolatedNormal =  interpolatedNormal.normalized; 
	    
	   // Transform local space normals to world space 
	   var hitTransform : Transform = hit.collider.transform; 
	   interpolatedNormal = hitTransform.TransformDirection(interpolatedNormal); 

	   // Display with Debug.DrawLine 
	   Debug.DrawRay(hit.point, interpolatedNormal); 
	}

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    void Update() {
        RaycastHit hit;
        if (!Physics.Raycast(Camera.main.ScreenPointToRay(Input.mousePosition), out hit))
            return;
        
        MeshCollider meshCollider = hit.collider as MeshCollider;
        if (meshCollider == null || meshCollider.sharedMesh == null)
            return;
        
        Mesh mesh = meshCollider.sharedMesh;
        Vector3[] normals = mesh.normals;
        int[] triangles = mesh.triangles;
        Vector3 n0 = normals[triangles[hit.triangleIndex * 3 + 0]];
        Vector3 n1 = normals[triangles[hit.triangleIndex * 3 + 1]];
        Vector3 n2 = normals[triangles[hit.triangleIndex * 3 + 2]];
        Vector3 baryCenter = hit.barycentricCoordinate;
        Vector3 interpolatedNormal = n0 * baryCenter.x + n1 * baryCenter.y + n2 * baryCenter.z;
        interpolatedNormal = interpolatedNormal.normalized;
        Transform hitTransform = hit.collider.transform;
        interpolatedNormal = hitTransform.TransformDirection(interpolatedNormal);
        Debug.DrawRay(hit.point, interpolatedNormal);
    }
}