Recently, while reading the code of Skia's new GPU backend "Graphite", I noticed that they did not use a technology like "libtess2" to triangulate paths, but instead used "stencil then cover" or its variants. Details can be found in their code (https://github.com/google/skia/blob/5d8b4bc3c7133e38dcae7b76cd708ed4649c13d1/src/gpu/graphite/Device.cpp#L1103-L1121) and in their implementation of the TessellateWedgesRenderStep (https://github.com/google/skia/blob/main/src/gpu/graphite/render/TessellateWedgesRenderStep.cpp).

In my opinion, "stencil then cover" has many benefits, such as not requiring triangulation techniques like libtess2, thus saving CPU time. Additionally, it can use a single render pass for convex paths without triangulation, and it's easier to design methods for parallel drawing of curves using GPUs without pre-computing vertices through CPU or compute shaders.

Of course, "stencil then cover" also has drawbacks, such as the need for 2-pass or 3-pass when drawing a path. However, since there is no switching of the RenderTarget during the process, it doesn't seem to have a significant impact on performance.

I'm curious as to why Impeller didn't choose the technical solution of "stencil then cover"? @chinmaygarde @bdero, would you mind enlightening me? Thank you!