This repo contains the new prototype for a new compute-centric 2D GPU renderer.
It succeeds the previous prototype, [piet-metal].
## Goals
The main goal is to answer research questions about the future of 2D rendering:
* Is a compute-centered approach better than rasterization ([Direct2D])? How much so?
* To what extent do "advanced" GPU features (subgroups, descriptor arrays) help?
Another goal is to explore a standards-based, portable approach to GPU compute.
## Non-goals
There are a great number of concerns that need to be addressed in production:
* Compatibility with older graphics hardware (including runtime detection)
* Asynchrony
* Swapchains and presentation
## Notes
A more detailed explanation will come. But for now, a few notes.
### Why not gfx-hal?
It makes a lot of sense to use gfx-hal, as it addresses the ability to write kernel and runtime code once and run it portably. But in exploring it I've found some points of friction, especially in using more "advanced" features. To serve the research goals, I'm enjoying using Vulkan directly, through [ash], which I've found does a good job tracking Vulkan releases. One example is experimenting with `VK_EXT_subgroup_size_control`.
The hal layer in this repo is strongly inspired by gfx-hal, but with some differences. One is that we're shooting for a compile-time pipeline to generate GPU IR on DX12 and Metal, while gfx-hal ships [SPIRV-Cross] in the runtime. To access [Shader Model 6], that would also require bundling [DXC] at runtime, which is not yet implemented (though it's certainly possible).
The case for wgpu is also strong, but it's even less mature. I'd love to see it become a solid foundation, at which point I'd use it as the main integration with [druid].
In short, the goal is to facilitate the research now, collect the data, and then use that to choose a best path for shipping later.
