title: What is the range of OpenGL texture ID?
body: <p>I have an object which owns a property Texture_ID. I need to initialize the value for Texture_ID in constructor, so I want some value unused by OpenGL to present that the texture is not yet set. </p>
  
  <p>I don't know whether zero (0) is a good value? If there is a range that OpenGL applies to texture IDs, I want a value out of this range. Any idea?</p>