The important aspect is that it allows knowing the uniforms that will
be used by a set of processors without having to create ProgramImpls.
GrProcessor subclasses specify uniforms at creation time in a similar
style to how GrGeometryProcessors already specify attributes. That is,
they initialize a span of structs describing the uniform which may
contain void uniforms that are skipped. Unlike attributes, the struct
contains an offset into the processor where the data is stored.
GrUniformAggregator is used to collect the uniforms from all processors
that compose a draw and mangle their names. The ProgramImpl subclasses
query the aggregator for their uniform names when emitting code.
The old system for uniforms is left intact and only three processors,
one GP, one FP, and one XP, are updated to use the new system.
Some pieces that are missing before everything can be moved over:
-support for uniforms not owned by GrProcessor (e.g. rt-adjust)
-support for samplers
-helpers for common patterns
(e.g. GrGeometryProcessor::ProgramImpl::setupUniformColor(),
and the various matrix helpers on ProgramImpl)
Bug: skia:12182
Change-Id: I21c1b7a8940eb9b8aad003f5a2569e43977a33d2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/440841
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
10c9f36bdd