msaa: Test that the "centroid" interpolation qualifier works correctly.

This patch adds tests to verify that:

- When GL_MULTISAMPLE is disabled, the "centroid" keyword is ignored,
  and interpolation is performed at pixel centers (consistent with the
  GL rules for non-antialiased rendering).

- When GL_MULTISAMPLE is enabled and the "centroid" keyword is used,
  interpolation is performed at a location within the boundary of the
  triangle.  The test also verifies that errors introduced into
  derivatives are kept within reasonable bounds.

- When GL_MULTISAMPLE is enabled and the "centroid" keyword is absent,
  derivatives are accurate.

Verified using nVidia's proprietary binary driver for Linux.

Reviewed-by: Chad Versace <chad.versace@linux.intel.com>

0 files changed, 0 insertions, 0 deletions