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.

Note: A textureCoord requires the collider to be a MeshCollider.

// 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.