This removes the GPU transform stage, changes shaders to reference transforms directly from the scene, and modifies the render context to maintain a transform stack.
This is the core logic for robust dynamic memory. There are changes to both shaders and the driver logic.
On the shader side, failure information is more useful and fine grained. In particular, it now reports which stage failed and how much memory would have been required to make that stage succeed.
On the driver side, there is a new RenderDriver abstraction which owns command buffers (and associated query pools) and runs the logic to retry and reallocate buffers when necessary. There's also a fairly significant rework of the logic to produce the config block, as that overlaps the robust memory.
The RenderDriver abstraction may not stay. It was done this way to minimize code disruption, but arguably it should just be combined with Renderer.
Another change: the GLSL length() method on a buffer requires additional infrastructure (at least on Metal, where it needs a binding of its own), so we now pass that in as a field in the config.
This also moves blend memory to its own buffer. This worked out well because coarse rasterization can simply report the size of the blend buffer and it can be reallocated without needing to rerun the pipeline. In the previous state, blend allocations and ptcl writes were interleaved in coarse rasterization, so a failure of the former would require rerunning coarse. This should fix#83 (finally!)
There are a few loose ends. The binaries haven't (yet) been updated (I've been testing using a hand-written test program). Gradients weren't touched so still have a fixed size allocation. And the logic to calculate the new buffer size on allocation failure could be smarter.
Closes#175
Adds a test to visualize the blend modes. Fixes a dumb bug in blend.h and also a more subtle issue where default blending is not the same as clipping, as the former needs to always push a blend group (to cause isolation) and the latter does not. This might be something we need to get back to.
This should fix the rendering, so it fairly closely resembles the Mozilla reference image. There's also a compile-time switch to disable sRGB conversion, which is (sadly) needed for compatible rendering.
Split the blend stack into register and memory segments. Do blending in registers up to that size, then spill to memory if needed.
This version may regress performance on Pixel 4, as it uses common memory for the blend stack, rather than keeping that memory read-only in fine rasterization, and using a separate buffer for blend stack. This needs investigation. It's possible we'll want to have single common memory as a config option, as it pools allocations and decreases the probability of failure.
Also a flaw in this version: there is no checking of memory overflow.
For understanding code history: this commit largely reverts #77, but there were some intervening changes to blending, and this commit also implements the split so some of the stack is in registers.
Closes#156
The blending math had two errors: first, colors were not separated for the purpose of blending (blending was wrongly applied to premultiplied values), and second, alpha was applied over-aggressively to the alpha channel.
This PR does *not* address the issue of gamma correctness. That is a complex issue and should probably be handled in the short term by disabling sRGB conversions and doing the internal math in sRGB color space rather than linear. This will degrade the quality of antialiasing but on the other hand give spec-compliant results for compositing.
We remove the plus-darker mode as its specification does not appear to be valid. The plus-lighter mode remains as it is quite useful for cross-fading effects.
Also the generated shaders were compiled on mac so the DXIL is unsigned. Those should be compiled on Windows before this PR is merged. (and we should figure out a better strategy for all that)
This commit implements actual rendering for the new piet-scene crate.
In particular, it adds a new EncodedSceneRef type in piet_gpu::encoder to store references to the raw stream data. This is used as a proxy for both PietGpuRenderContext and piet_scene::scene::Scene to feed data into the renderer.
Much of this is still hacky for expedience and because the intention is to be a transitional state that maintains both interfaces until we can move to the new scene API and add a wrapper for the traditional piet API.
The general structure and relationships between these crates need further discussion.
We always do BeginClip/EndClip if it's a solid tile and the blend mode
is not default.
Also fix missing entry in pipeline layout (affects Vulkan but not Metal).
This patch switches to a variable size encoding of draw objects.
In addition to the CPU-side scene encoding, it changes the representation of intermediate per draw object state from the `Annotated` struct to a variable "info" encoding. In addition, the bounding boxes are moved to a separate array (for a more "structure of "arrays" approach). Data that's unchanged from the scene encoding is not copied. Rather, downstream stages can access the data from the scene buffer (reducing allocation and copying).
Prefix sums, computed in `DrawMonoid` track the offset of both scene and intermediate data. The tags for the CPU-side encoding have been split into their own stream (again a change from AoS to SoA style).
This is not necessarily the final form. There's some stuff (including at least one piet-gpu-derive type) that can be deleted. In addition, the linewidth field should probably move from the info to path-specific. Also, the 1:1 correspondence between draw object and path has not yet been broken.
Closes#152
This just runs ninja on the piet-gpu/shaders on a Windows machine, so
translated shaders match the existing pipeline.
At some point, we'll rework this to reduce friction.
* Add blend and composition mode enums to API
* Mirror these in the shaders
* Add new public blend function to PietGpuRenderContext that mirrors clip
* Plumb the modes through the pipeline from scene to kernel4
This PR reworks the clip implementation. The highlight is that clip bounding box accounting is now done on GPU rather than CPU. The clip mask is also rasterized on EndClip rather than BeginClip, which decreases memory traffic needed for the clip stack.
This is a pretty good working state, but not all cleanup has been applied. An important next step is to remove the CPU clip accounting (it is computed and encoded, but that result is not used). Another step is to remove the Annotated structure entirely.
Fixes#88. Also relevant to #119
Also updates comment.
We know the implementation is incomplete and needs refinement, but it
seems useful to commit as a starting point for further work.
