Safari Technology Preview 91 gets beta support for the WebGPU JavaScript API and WSL

3 min read

Yesterday, Apple announced that Safari Technology Preview 91 now supports the beta version of the new WebGPU graphics API and its shading language, Web Shading Language (WSL). You can enable the WebGPU beta support by selecting Experimental Features > WebGPU in the Developer menu.

The WebGPU JavaScript API

WebGPU is a new graphics API for the web that aims to provide “modern 3D graphics and computation capabilities.” It is a successor to WebGL, a JavaScript API that enables 3D and 2D graphics rendering within any compatible browser without the need for a plug-in. It is being developed in the W3C GPU for the Web Community Group with engineers from Apple, Mozilla, Microsoft, Google, and others.

Read also: WebGL 2.0: What you need to know

Comparing WebGPU and WebGL

WebGPU is different from WebGL in the respect that it is not a direct port of any existing native API, but a similarity between the two is that they both are accessed through JavaScript. However, the team does have plans to make it accessible through WebAssembly as well in the future.

In WebGL, rendering a single object requires writing a series of state-changing calls. On the other hand, WebGPU combines all the state-changing calls into a single object named pipeline state object. It validates the state after the pipeline is created to prevent expensive state analysis inside the draw call. Also, wrapping an entire pipeline state in a single function call reduces the number of exchanges between Javascript and WebKit’s C++ browser engine.

Similarly, resources in WebGL are bound one-by-one, while WebGPU batches them up into bind groups. The team explains, “In both of these examples, multiple objects are gathered up together and baked into a hardware-dependent format, which is when the browser performs validation. Being able to separate object validation from object use means the application author has more control over when expensive operations occur in the lifecycle of their application.

The main focus area of WebGPU is to provide improved performance and ease of use as compared to WebGL. The team compared the performance of the two using the 2D graphics benchmark, MotionMark. The performance test they wrote measured how many triangles each with different properties were rendered while maintaining 60 frames per second. Each triangle was rendered with a different draw call and bind group.

WebGPU showed a substantially better performance than WebGL:

WebGPU Performance

Source: Apple

WHLSL is now renamed to WSL

In November last year, Apple proposed a new shading language for WebGPU named Web High-Level Shading Language (WHLSL), which was source-compatible with HLSL. After receiving the community feedback, they updated the language to be compatible with OpenGL Shading Language (GLSL), which is a pretty commonly used language among the web developers. Apple renamed this version of the language to Web Shading Language (WSL) and describes it as “simple, low-level, and fast to compile.”

Read also: Introducing Web High Level Shading Language (WHLSL): A graphics shading language for WebGPU

There are many Web developers using GLSL today in WebGL, so a potential browser accepting a different high-level language, like HLSL, wouldn’t suit their needs well. In addition, a high-level language such as HLSL can’t be executed faithfully on every platform and graphics API that WebGPU is designed to execute on,” the team wrote.

Check out the official announcement by Apple to know more in detail.

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