private void Init(InkCanvas canvas)
 {
     material           = GetComponent <MeshRenderer>().sharedMaterial;
     defaultMainTexture = canvas.GetMainTexture(material.name);
     paintMainTexture   = canvas.GetPaintMainTexture(material.name);
     defaultNormalMap   = canvas.GetNormalTexture(material.name);
     paintNormalMap     = canvas.GetPaintNormalTexture(material.name);
     defaultHeightMap   = canvas.GetHeightTexture(material.name);
     paintHeightMap     = canvas.GetPaintHeightTexture(material.name);
     StartCoroutine(TextureLerp());
 }