The CPU fallback of the compute renderer needs ReadPixels data in OpenGL
format (origin at bottom left). Unfortunately, the OpenGL driver
automatically mirrors images in the Y-axis to match the top left origin
image.RGBA.
Remove the mirroring from the driver and introduce a DownloadImage to
restore the old behaviour.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
It is no longer necessary for outside users of package gpu to explicitly
initialize a specific driver. The Direct3D driver is already internal,
this moves the OpenGL driver internally as well. The rename to opengl is
to avoid the name clash with the low-level "gioui.org/internal/glimpl"
package that we're about to rename.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Elias Naur