tree 4823afdb2e8eb02e1c13ec97e9a6916da6d4549f
parent 10c3776b4432cb319157bd0fa3e219e94e2580be
author Michael Ludwig <michaelludwig@google.com> 1535659698 -0400
committer Skia Commit-Bot <skia-commit-bot@chromium.org> 1535662261 +0000

Support input color argument to process() function in sksl .fp files

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This expands sksl's capabilities with .fp files. Previously, it was possible to declare "in fragmentProcessor foo" and emit it automatically when "process(foo);" was called. This adds a variant of process that takes a second argument, which must be a half4 expression. This argument specifies the value, or dynamic expression calculated earlier in the parent shader, to use as sk_InColor by the child.

The CL is longer than anticipated because of properly handling dependencies between previous sksl statements and the input to the child. The original writeEmitCode() collected all extra emission code (the calls to build->emitChild) and put them before any call to codeAppendf. This makes it impossible to use a parent's variable, or the output of another child, as the input for process.

To solve this, there is now a flushEmittedCode() function that takes over the logic of outputting the extra emission code and the necessary codeAppendf calls. When invoked, it (by default) only appends completed sksl statements, and places any current expression back at the beginning of the output stream. It now updates fFormatArgs and fExtraEmitCodeCode as it consumes their contents. This allows writeFunctionCall() for a call to "process" to flush all previous statements before it adds its emit child code.

Bug: skia:
Change-Id: I63c41af6f3e0620aa890d10d14436ee6244f0051
Reviewed-on: https://skia-review.googlesource.com/148395
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>