title: texture coordinate precision
body: <p>I am calculating uv coordinates for a bitmap font texture.
  Texture size is 1024 x 1024. The uv coords are calculated on a pixel
  position base. Here is the code.</p>
  
  <pre><code>  uv_run   = ( int8_t* )&amp;bfs-&gt;uv[ bfs-&gt;st_ch_ind &lt;&lt; 2 ];
    t_c_size = sizeof( t_c ); 
    x_pos    = x_st_pix;
    y_pos    = y_pix_delta * ( bfs-&gt;col_numb - 1 ) + 28;    // !!! this delta 28 has been added to center the chars
  
    for( c1 = 0; c1 &lt; bfs-&gt;col_numb; c1++ )
    {
      /***********************/
      /*   process one row   */
      /***********************/
      for( c2 = 0; c2 &lt; bfs-&gt;row_numb; c2++ )
      {
           /*******************************************/      
           /*   position in texture = x_pos / y_pos   */
           /*   this is lower left corner -&gt; uv[ 0    */
           /*******************************************/    
           t_c[ 0 ].u = x_pos * uv_pix_fkt;
           t_c[ 0 ].v = y_pos * uv_pix_fkt;
  
  
           /*******************************************/      
           /*   go to lower right corner -&gt; uv[ 1 ]   */
           /*******************************************/    
           x_pos += x_pix_delta;
           t_c[ 1 ].u = x_pos * uv_pix_fkt;
           t_c[ 1 ].v = y_pos * uv_pix_fkt;
  
           /*******************************************/      
           /*   go to upper right corner -&gt; uv[ 2 ]   */
           /*******************************************/    
           y_pos += y_pix_delta;
           t_c[ 2 ].u = x_pos * uv_pix_fkt;
           t_c[ 2 ].v = y_pos * uv_pix_fkt;
  
           /*******************************************/      
           /*   go to upper left corner -&gt; uv[ 3 ]   */
           /*******************************************/    
           x_pos -= x_pix_delta;
           t_c[ 3 ].u = x_pos * uv_pix_fkt;
           t_c[ 3 ].v = y_pos * uv_pix_fkt;
  
           y_pos -= y_pix_delta;
           x_pos += x_pix_delta; 
           memcpy( uv_run, t_c, t_c_size );
           uv_run += t_c_size;            
      }
  
      x_pos = x_st_pix;
      y_pos -= y_pix_delta;
  </code></pre>
  
  <p>This calculation does not hit the exact ( thought to be ) destination.
  I have an offset in the y direction of about 28 pixels!!!
  The source data comes from a DDS compressed file that has been created with compressonator.
  I thought it is possible to hit every pixel on a texture with uv coos?</p>