let the plaer draw in unity
// 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();
}
}