[graphite] Define and write ssbo index attributes
Eventually we'll want this to index into a shared storage buffer of
render step uniforms, which can include another index into a buffer of
paint uniforms. But since we'll likely implement shared storage buffer
support for paint uniforms first, for now this can just index into the
paint uniform buffer directly.
Bug: b/238621785
Change-Id: I09c3cafb6e80a3cfe40e9a8304c1d50e75081738
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/566885
Commit-Queue: James Godfrey-Kittle <jamesgk@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
22 files changed
