Commit 243d0f899e443cd931c78aba7489382dff79edbb
2020-10-08T21:54:45
Vulkan: Avoid content restore by detecting no-op stencil Previously, as long as stencil was enabled, it was considered that it is also being modified. This caused stencil invalidate to be undone in a number of situations, such as: - glEnable(GL_STENCIL_TEST); // with func/ops default - glDrawArrays(); - glInvalidateFramebuffer([GL_STENCIL_ATTACHMENT]); - glClear(GL_DEPTH_BUFFER_BIT); - Close render pass In the above scenario, invalidation of stencil was undone at the end of render pass. In this change, the following cases are considered read-only stencil: - Func = GL_NEVER, stencilFail = GL_KEEP - Func = GL_ALWAYS, stencilPassDepth* = GL_KEEP - stencilFail = GL_KEEP, stencilPassDepth* = GL_KEEP Note that while the above scenario is fixed for no-op stencil, a similar issue persists if stencil was not no-op. The reason stencil invalidate is undone in that case is due to the fact that it's assumed any command after the invalidate call will be a draw call that outputs to stencil, but that is not the case with the glClear call in this example. Bug: angleproject:4836 Change-Id: Ie2ea2d52b7c8ee2394f5456773a7ef434e2b2b16 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2461465 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Ian Elliott <ianelliott@google.com>