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* Add the base of the example. May need refining and definitely fact-checking. * Start change to changelog. * Complete changelog change for repeated-compute. * Apply suggestion to fix typos. Co-authored-by: Alphyr <47725341+a1phyr@users.noreply.github.com> * Add storage-texture example which currently works native but needs to be changed to work for wasm. [no ci] * repeated-compute now works on the web. [no ci] * `storage-texture` now works on the web as well as native. * Format because I forgot to do that (ugh). * Add `storage-texture` to changelog. * Add `render-to-texture` example. * Not all the files got git added. Fixed it. * Add `render-to-texture` to changelog. * Make better readme's and add examples to said readme's. * Oops. Put the example updates in the wrong place. * Add `uniform-values` example. * Apply clippy suggestions. * Improved readme's and documentation. * Fmt. Turning into the Joker rn. * Make instructions for examples on the web more clear. \(Fmt and clippy happy\) * hello-workgroups It doesn't work. * Add basic comments and readme to hello-workgroups. * Add hello-synchronization example. Currently doesn't have any tests but those should be added later. * Forgot to check wasm compatibility for hello-synchronization. Fixed it. * Add test for hello-synchronization. * Make my examples downlevel defaults. * Make uniform-values downlevel defaults. (Forgot to do that last commit.) * Fix clippy doc complaints. * Didn't fully fix the docs last commit. Got it here I think. * Fix redundant bullet point in examples/hello-workgroups/README.md. * Trim down the introduction section of examples/hello-workgroups/README.md. * Add technical links section to examples/hello-workgroups/README.md. * Use idiomatic Rust comments, break up big text wall into paragraphs, and fix some spelling errors. * Move output image functions into examples/common and give output_image_wasm some upgrades. * Modify changelog for moving output_image_native and output_image_wasm into wgpu-example. * Fix output_image_wasm. (Formerly did not handle pre-existing output image targets.) * Make a multiline comment be made of single lines to be more ideomatic. * "Fix" more multiline comments. I think this is actually the last of them. * Make the window a consistant, square size that's convenient for viewing. * Make the window on uniform-values not endlessly poll, taking up 100% of the main thread in background at idle. Also, change layout a little and make native use nanos by default for logging. * Make execute in hello-synchronization return a struct of vecs instead of using out parameters. * Didn't realize the naming of wgpu_example::framework so I moved my common example utility functions into wgpu_example::utils. * Add add_web_nothing_to_see_msg function to replace all the instances of adding "open the console" messages across the examples. * Add small documentation to add_web_nothing_to_see_msg and change it to use h1 instead of p. * Add documentation to output_image_native and output_image_wasm in examples/common. * Do better logging for output image functions in wgpu-example::utils. * Remove redundant append_child'ing of the output image element in wgpu-example::utils::output_image_wasm. * Fix error regarding log message for having written the image in wgpu-example::utils::output_image_native. * Fmt. * In examples/README.md, re-arrange the examples in the graph to be in alphabetical order. * Fix changlog item regarding wgpu-example::utils and the output image functions. * Move all the added examples into one changelog item that lists all of them. * Updated table in examples/README.md with new examples. Added new features to the table to accurately represent the examples.\n\nFor the new features, not all old examples may be fully represented. * Fix inaccurate comment in hello-workgroups/src/shader.wgsl. * Update examples/README.md to include basic descriptions of the basic examples as well as hints on how examples build off of each other. * Remove `capture` example. See changelog entry for reasoning. * Fix typo in hello-workgroups/shader.wgsl * Change the method of vertex generation in the shader code of render-to-texture to make it more clear. * Modify/correct message in repeated-compute/main.rs regarding the output staging buffer. * Update message in uniform-values/main.rs about writing the app state struct to the input WGSL buffer. * Add notice in repeated-compute/main.rs about why async channels are necessary (portability to WASM). * Revise comment in uniform-values/main.rs about why we don't cast the struct using POD to be more clear. * Change uniform-values to use encase for translating AppState to WGSL bytes. * Cargo & Clippy: My two best friends. * Add MIT-0 to the list of allowed liscences. * Fix docs for wasm. --------- Co-authored-by: Alphyr <47725341+a1phyr@users.noreply.github.com>
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hello-synchronization
This example is
- A small demonstration of the importance of synchronization.
- How basic synchronization you can understand from the CPU is preformed on the GPU.
A Primer on WGSL Synchronization Functions
The official documentation is a little scattered and sparse. The meat of the subject is found here but there's also a bit on control barriers here. The most important part comes from that first link though, where the spec says "the affected memory and atomic operations program-ordered before the synchronization function must be visible to all other threads in the workgroup before any affected memory or atomic operation program-ordered after the synchronization function is executed by a member of the workgroup." And at the second, we also get "a control barrier is executed by all invocations in the same workgroup as if it were executed concurrently."
That's rather vague (and it is by design) so let's break it down and make a comparison that should make that sentence come a bit more into focus. Barriers in Rust fit both bills rather nicely. Firstly, Rust barriers are executed as if they were executed concurrently because they are - at least as long as you define the execution by when it finishes, when Barrier::wait finally unblocks the thread and execution continues concurrently from there. Rust barriers also fit the first bill; because all affected threads must execute Barrier::wait in order for execution to continue, we can guarantee that all (synchronous) operations ordered before the wait call are executed before any operations ordered after the wait call begin execution. Applying this to WGSL barriers, we can think of a barrier in WGSL as a checkpoint all invocations within each workgroup must reach before the entire workgroup continues with the program together.
There are two key differences though and one is that although Rust barriers don't enforce that atomic operations called before the barrier are visible after the barrier, WGSL barriers do. This is incredibly useful and important though and is demonstrated in this example.
Another is that WGSL's synchronous functions only affect memory and atomic operations in a certain address space. This applies to the whole 'all atomic operations called before the function are visible after the function' thing. There are currently three different synchronization functions:
storageBarrierwhich works in the storage address space and is a simple barrier.workgroupBarrierwhich works in the workgroup address space and is a simple barrier.workgroupUniformLoadwhich also works in the workgroup address space and is more than just a barrier. Read up on all three here.