RaycastHit.textureCoord

Description

The uv texture coordinate at the collision location.

A ray is fired into the scene. The textureCoord is the location where the ray has hit a collider. RaycastHit._textureCoord is a texture coordinate when a hit occurs. A Vector2 zero is returned if no mesh collider is present in the GameObject.

// Attach this script to a camera and it will paint black pixels in 3D 
// on whatever the user clicks. Make sure the mesh you want to paint 
// on has a mesh collider attached.

var cam: Camera;

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


function Update () {
	// Only when we press the mouse
	if (!Input.GetMouseButton(0))
		return;

	// Only if we hit something, do we continue
	var hit : RaycastHit;
	if (!Physics.Raycast(cam.ScreenPointToRay(Input.mousePosition), hit))
		return;

	// Just in case, also make sure the collider also has a renderer
	// material and texture. Also we should ignore primitive colliders.
	var rend : Renderer = hit.transform.GetComponent.<Renderer>();
	var meshCollider = hit.collider as MeshCollider;

	if (rend == null || rend.sharedMaterial == null ||
		rend.sharedMaterial.mainTexture == null || meshCollider == null)
		return;

	// Now draw a pixel where we hit the object
	var tex : Texture2D = rend.material.mainTexture as Texture2D;
	var pixelUV : Vector2 = hit.textureCoord;
	pixelUV.x *= tex.width;
	pixelUV.y *= tex.height;

	tex.SetPixel(pixelUV.x, pixelUV.y, Color.black);

	tex.Apply();
}

// Write black pixels onto the GameObject that is located
// by the script. The script is attached to the camera.
// Determine where the collider hits and modify the texture at that point.
//
// Note that the MeshCollider on the GameObject must have Convex turned off. This allows
// concave GameObjects to be included in collision in this example.
//
// Also to allow the texture to be updated by mouse button clicks it must have the Read/Write 
// Enabled option set to true in its Advanced import settings.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {

	public Camera cam;

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

	void Update()
	{
		if (!Input.GetMouseButton(0))
			return;

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

		Renderer rend = hit.transform.GetComponent<Renderer>();
		MeshCollider meshCollider = hit.collider as MeshCollider;
		
		if (rend == null || rend.sharedMaterial == null || rend.sharedMaterial.mainTexture == null || meshCollider == null)
			return;

		Texture2D tex = rend.material.mainTexture as Texture2D;
		Vector2 pixelUV = hit.textureCoord;
		pixelUV.x *= tex.width;
		pixelUV.y *= tex.height;

		tex.SetPixel((int)pixelUV.x, (int)pixelUV.y, Color.black);
		tex.Apply();
	}
}

See Also: Physics.Raycast, Physics.Linecast, Physics.RaycastAll.