The WebGPU graphics API provides useful graphics features. But it also has some limitations you need to be aware of:
Although WebGPU unlocks useful graphics features, there are a few it doesn’t support yet:
WebGPU is currently experimental and not supported by all browsers and devices. For more information, refer to the MDN Web docs on Accessing a device and Browser compatibility. For browser support, refer to Can I use: WebGPU.
There are a few limitations to compute shader in Web.
You can use structured buffers, RWStructuredBuffer, but not RWBuffer in compute shaders.
Limited read-write storage texture formats
WebGPU only supports a limited set of texture formats for read-write storage textures in compute shaders. HLSL doesn’t explicitly state the access type of a storage texture, so it’s based on usage.
RWTexture2D<float> tex; // storage texture
tex[uv] = 1.0f; // write only
tex[uv] += 1.0f; // read-write
Write-only storage textures are generally much better supported. Refer to Texture format limitations.
In WebGPU, you must only call barrier functions from uniform control flow. Otherwise, WebGPU fails to compile the shader. Uniform control flow ensures that all threads in a thread group follow the same execution path and reach the barrier simultaneously.
The following are HLSL barrier functions:
GroupMemoryBarrierGroupMemoryBarrirWithGroupSyncDeviceMemoryBarrierDeviceMemoryBarrierWithGroupSyncAllMemoryBarrierAllMemoryBarrierWithGroupSyncWebGPU doesn’t support async compute.
WebGPU doesn’t provide support for the following features:
Wave Intrinsics (WaveBasic, WaveVote, WaveBallot, WaveMath, WaveMultiPrefix)
QuadShuffle
Int64
Native16Bit
WebGPU doesn’t support synchronous readback of buffer or texture data from the GPU to the CPU. The following functions will not work:
Instead, use the AsyncGPUReadback API to read buffer or texture data from the GPU to the CPU. For screen captures, use ScreenCapture.CaptureScreenshotIntoRenderTexture along with AsyncGPUReadback.
For information about WebGPU texture format capabilities, refer to the W3 documentation on WebGPU. Some formats are more restrictive than on other APIs, especially for storage texture usage.
For example, WebGPU doesn’t support RGBA8 or RHalf as a read-write storage texture format. If you do create a RenderTexture with that format, you must set enableRandomWrite to false, which is the default value.
However, WebGPU supports RFloat as a storage texture format, so if you create a RenderTexture with RFloat format, enableRandomWrite doesn’t need to be false.
You can use SystemInfo.GetCompatibleFormat to find a format that will work for a given usage.
The output type of a fragment shader must have a greater or equal number of channels as the target render texture format.
If the RenderTexture is RGBA, it has 4 channels. The fragment shader must output a float4 or half4. If it returns a float or half, WebGPU will encounter an error because there are channels of the render texture that will be uninitialized.
If a RenderTexture is R8, it has 1 channel. The fragment shader can then output a float or half. The fragment shader can also return a float4 or half4, and the extra output channels will be ignored.
The number of textures you can access from a shader is limited to 16 on many platforms. This limit can hit by the terrain renderer, especially with layer textures. This can make terrain rendering problematic for WebGPU. It is recommended that you limit the number of terrain texture layers you use.
Unity Web supports dynamic font rendering similar to other Unity platforms. However, Unity Web doesn’t have access to the fonts installed on the user’s machine, so if you want to use any fonts, include them in the project folder (including any fallback fonts for international characters, or bold/italic versions of fonts), and set as fallback font names.
Unity Web only supports Baked Global Illumination. Realtime Global Illumination isn’t currently supported in Web. Also, Unity Web supports non-directional lightmaps only.
You can’t use VideoClipImporter to import video clips to your Unity project because it might increase the initial asset data download size and prevent network streaming. To use video playback in Web:
URL option in the VideoPlayer component.StreamingAssets directory to use the built-in network streaming of your browser.Due to limited available memory in Web, don’t include unwanted shader variants because it can lead to unnecessary memory usage. Therefore, it’s recommended to familiarize yourself with shader variants and shader stripping. Also, take extra care to ensure that you don’t add shaders with too many variants (for example, Unity’s Standard Shader) to the Always-included Shaders section in Graphics Settings.