Storage allocation was quite wrong in the general case.
1) We can't pass unsized texture formats to immutable storage
allocations, so we need to check for that.
2) Second, when allocating mutable storage on GLES, apparently
the driver is allowed to peek at the external pixel type. The
texture can then only get data in the pixel type passed
at storage allocation time.
(I guess that, for the sake of simplicity, the drivers are allowed
not to perform any pixel conversions.)
I'm still not convinced about the wording in the GLES2/3
specifications, but apparently ANGLE behaves this way, so we need
to fix this kind of allocation. Unfortunately the only way
is to ask, at storage allocation time, what's the external
pixel format/type, so we need to introduce an allocateStorage
overload taking those as arguments and using them for the
glTexImage* calls.
Task-number: QTBUG-41822
Task-number: QTBUG-42623
Change-Id: Idf745d549f01c5db3e56e86cf9b1f53a77cfccc6
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>
279317b067