Previously, if a surface was transformed, it repainted as a whole,
regardless of the computed repaint region. As damage regions determine
repaint regions and whether a surface is considered for drawing at all,
this lead to disappearing surfaces if all surfaces were considered
transformed. Also transparent transformed surfaces were redrawn without
the surfaces below being properly redrawn, leading to alpha-saturation.
Fix that by making texture_region() use the proper global-to-surface
coordinate transformation for texture coordinates. This makes it
possible to call texture_region() also for transformed surfaces.
As texture coordinates may now lie outside the valid texture image, the
fragment shader is modified to check the fragment texture coordinates.
The special path texture_transformed_surface() is no longer used and is
removed.
This change fixes many of the rendering artifacts related to transformed
surfaces.
Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>
Pekka Paalanen
0e151bb487