* add comment for ClipInp::path_ix
* update comment for SceneBuilder drawtags
* remove copy of blend data through info buffer. Instead, update EndClip's DrawMonoid::scene_offset to point to the same scene data of the associated EndClip.
* Add comment about avoiding NaNs to inverse alpha divisions
* Change inverse alpha computations to use max(a, epsilon) rather than +
* Emit alpha component in blit fragment shader (enables support for partially transparent windows)
This just a collection of minor fixes to various things I noticed while looking over the code.
Adds a `Device::poll` call to the winit example.
Removes some lingering unnecessary `<f32>`s in the blit shaders.
Removes a duplicated bbox entry in the shared shader inclusion code and collapses nested `concat!`s.
Finally, it reintroduces the computation of separated alpha in the output of fine which I removed in a previous PR. This allows the `render_to_texture` mode to be useful for generating images that can be properly blended over other content. The blit shader has been changed to accommodate this.
A number of things weren't being computed correctly for strokes,
including bounding boxes and also incorrectly applying y_edge logic
(which is only correct for fills).
This creates a new Renderer type that offers fairly simple render_to_texture and render_to_surface methods, the latter of which handles the final blit internally. Also adds a util module with some helpers for device and surface creation.
There is a new winit example in piet-wgsl/examples/winit that shows how to make use of it all. This should be fairly trivial to adapt to glazier/xilem.
* add writeable image support to engine
* add external resources to engine
* update fine to output to a texture
* copy over original piet-gpu test scenes
* put it all in a pretty (resizable!) window
This adds a new dependency on peniko, reintroduces kurbo for geometry (!), removes the now defunct types from piet-scene and updates all the test scenes to use the new types.
This is a checkpoint of partly completed work. Much of the GPU side is done, very little of the CPU side.
For clips, the clip_els bindings (binding 6 of draw_leaf) are not added. Clip logic is missing from coarse. The overflow buffer is missing from fine, as is its size calculation in coarse (but it should work as long as the max depth fits within BLEND_STACK_SPLIT).
For gradients, the texture binding is missing (binding 6) is missing from fine, as is the infrastructure in engine to deal with texture resources, and of course porting over the logic to fill it.
The code is not tested, bugs may lurk.
Still one flaw, fat lines aren't expanded with strokes in path coarse rasterization. But that's a small visual ding, and can be fixed
That said, there is some really strange stuff going on in tile_alloc. It's using storage to do a uniform broadcast (the result of bump allocation for the workgroup), which is not great at all. It should be using workgroup storage, but on my mac it behaves as if the workgroup barrier is not in place. Investigating.
All streams of the scene are combined into a single buffer. This is very much like existing piet-gpu, however the various outputs from the compute stages (whether computed on CPU or GPU) will retain their separate bindings, which is more native to WGSL.
There's a touch of ergonomics loss, in particular when we do transforms we'll need to unmarshal them by hand, but I think overall not too bad.
This lets us use https://github.com/wgsl-analyzer/wgsl-analyzer for writing the wgsl files.
The imports (for wgsl-analyzer) have to be machine specific at the moment - to use this you need to configure .vscode/settings.json yourself. The alternative is to point them at static files on GitHub, which is tempting to make things easier, but would potentially go out of sync with what is actually used.
Starting an experimental port to WGSL shader language, using wgpu to run the examples. As of this commit, it's quite hacky and takes some shortcuts, but does render paths to a grayscale texture.
