title: What's the Meaning of Texture Coordinate in obj Files
body: <p>So here's the question: what do the values of texture coordinates represent? 
  For example, in my obj file, texture coordinates look like these:</p>
  
  <pre><code>vt 0.474178 0.050139
  vt 0.477308 0.050139
  vt 0.480438 0.050139
  vt 0.483568 0.050139
  </code></pre>
  
  <p>The size of my texture (bmp file) is 640*360. Does that mean (0.474178, 0.050139) in the obj file correspond to the (0.474178*640, 0.050139*360) point in the bmp file? That is, texture coordinates indicate the point position in bmp file by doing:</p>
  
  <pre><code> u*width_of_the_bmp,  v*height_of_the_bmp
  </code></pre>
  
  <p>And if I'm wrong, how can I get the corresponding correlation between vt and bmp point position? Because I want to get the RGB values for every vertex, and I can get the RGB values for every pixel in the bmp file, how to link these data together to get what I want? </p>