title: Vertex to Pixel Shader TEXCOORD interpolation precision issues
body: <p>I think I'm experiencing precision issues in the pixel shader when reading the texcoords that's been interpolated from the vertex shader.</p>
  <p>My scene constists of some very large triangles (edges being up to 5000 units long, and texcoords ranging from 0 to 5000 units, so that the texture is tiled about 5000 times), and I have a camera that is looking very close up at one of those triangles (the camera might be so close that its viewport only covers a couple of meters of the large triangles). When I pan the camera along the plane of the triangle, the texture is lagging and jumpy. My thought is that I am experiencing lack of precision on the interpolated texcoords.</p>
  <p>Is there a way to increase the precision of the texcoords interpolation?</p>
  <p>My first though was to let texcoord u be stored in double precision in the xy-components, and texcoord v in zw-components. But I guess that will not work since the shader interpolation assumes there are 4 separate components of single-precision, and not 2 components of double-precision?</p>
  <p>If there is no solution on the shader side, I guess I'll just have to tesselate the triangles into finer pieces? I'd hate to do that just for this issue though.. Any ideas?</p>
  <p>EDIT: The problem is also visible when printing texcoords as colors on the screen, without any actual texture sampling at all.</p>