title: OpenGL DirectX XNA Vertex uniqueness When use or not Indices?
body: <p>This is what I am getting when reading a FBX  File</p>
  
  <pre><code>Normals Count        = 6792
  TextureCoords Count =  6792
  Faces =                2264
  Vertices =             3366
  </code></pre>
  
  <p>What I dont get is why I have less Vertices than Normals / TextCoords</p>
  
  <p>I need your help to understand when I should use Index Buffer and when not</p>
  
  <p>Index buffers help to reduce bandwidth to the Graphics Card, got it.
  Index buffers help to not repeat the vertex with the SAME data, got it.</p>
  
  <p>Let's say I have a model with 1000 Vertices and 3000 Faces formed from those Vertices,
  thus an Index Buffer of  9000 elements  (3 indices per face)</p>
  
  <p>I have 1000 unique Positions array  but 9000 unique TextCoords plus Normals array</p>
  
  <p>If the Vertices were only the Position, that is the best scenario for the Index Buffer,  no redundant Vertices</p>
  
  <p>But it happens that I also have TextureCoords and Normals, and per face they can have different values per Position, in other words, the Position shared between faces but with different attributes for each face</p>
  
  <p>So the uniqueness of the Vertex will be  -Position AND TextureCoord AND Normal-</p>
  
  <p>It will be unlikely I have repeated vertices with that full combination then the Indices are useless, right?</p>
  
  <p>I will need to repeat the Position for each TextureCoord AND Normal </p>
  
  <p>In the end seems I can't take advantage of having only 1000 Indexed-Positions</p>
  
  <p>Then my point is ,  I don't need Indices  right?  or am I missunderstanding the concepts?</p>