Like with interpolatAtSample this is also not really implementing the
according sampling and will only work correctly for pixels that are fully
covered, but since softpipe only supports one sample this is good enough
for now.
v2: Correct spelling (Roland Scheidegger)
Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>