feat(SPLAT): Replace manual SPZ loader with NianticLabs WASM implementation and enable 4-th order spherical harmonics by raymondyfei · Pull Request #18267 · BabylonJS/Babylon.js

raymondyfei · 2026-04-09T21:34:54Z

This PR replaces the existing manual TypeScript implementation of the SPZ (Splat Zip) loader with NianticLab's official SPZ implementation compiled to WASM (see NianticLabs SPZ for more details). The package was shipped to NPMJS as @adobe/spz because Adobe is responsible for NPM package publication. The primary goal is to improve the consistency and maintainability of loading Gaussian Splatting files within Babylon.js, making it future-proof.

In particular, this PR enables the support of the latest features, such as loading the SPZs with SH4, and vendor-specific extensions.

In addition, we enable the rendering of 4th-order spherical harmonics as it's a shipped feature in the latest version of SPZ.

Changes:

Adds @adobe/spz as a dependency in the loaders package, and calls spz.loadSpzFromBuffer() to directly load the SPZ through the WASM library.
Removes the manual GZip decompression stream and the custom bit-reading logic previously used to parse the SPZ format.
Adds support for the safe-orbit-camera extension loaded from an SPZ file.
Adds support for 4th-order spherical harmonics rendering in both WebGL and WebGPU shaders, where we added two optional textures for holding the data.

Popov72 · 2026-04-10T09:08:25Z

/azp run

azure-pipelines · 2026-04-10T09:08:35Z

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bjsplat · 2026-04-10T09:09:55Z

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To prevent this PR from going to the changelog marked it with the "skip changelog" label.

bjsplat · 2026-04-10T09:09:56Z

Reviewer - this PR has made changes to one or more package.json files.

bjsplat · 2026-04-10T09:24:59Z

Snapshot stored with reference name:
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bjsplat · 2026-04-10T09:28:54Z

Interaction tests

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/18267/merge/testResults/interactionplaywright/index.html

bjsplat · 2026-04-10T09:44:28Z

Visualization tests for WebGPU

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/18267/merge/testResults/webgpuplaywright/index.html

bjsplat · 2026-04-10T09:52:34Z

WebGL2 visualization test reporter:

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/18267/merge/testResults/webgl2playwright/index.html

ryantrem · 2026-04-10T15:52:29Z

For the browser, it looks like the wasm is embedded in the js (not a separate .wasm file), so I guess there should be no separate download of a .wasm file or any .wasm hosting or csp or anything like that, which seems good.
For babylon native, we currently have no WebAssembly support, so I think making this change would mean losing support for splat/spz in native. :/

raymondyfei · 2026-04-10T18:55:24Z

I think making this change would mean losing support for splat/spz in native

Does Babylon Native use V8 or JavaScriptCore? I thought these two supported WebAssembly. Or is there anything we could do to add support?

sebavan · 2026-04-10T19:54:01Z

/azp run

azure-pipelines · 2026-04-10T19:54:11Z

Azure Pipelines successfully started running 1 pipeline(s).

bjsplat · 2026-04-10T19:56:06Z

Reviewer - this PR has made changes to one or more package.json files.

bjsplat · 2026-04-10T20:17:18Z

Interaction tests

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/18267/merge/testResults/interactionplaywright/index.html

ryantrem · 2026-04-10T20:17:51Z

I think making this change would mean losing support for splat/spz in native

Does Babylon Native use V8 or JavaScriptCore? I thought these two supported WebAssembly. Or is there anything we could do to add support?

BN works with V8, JavaScriptCore, Chakra, Hermes (via JSI), and there is some experimental work with QuickJS as well. I believe full wasm support is a bit split across V8/JSC and the host browser, and I also believe wasm is restricted on iOS unless it is in the browser (Safari). @bghgary thoughts?

bjsplat · 2026-04-10T20:31:58Z

Visualization tests for WebGPU

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/18267/merge/testResults/webgpuplaywright/index.html

bjsplat · 2026-04-10T20:36:55Z

WebGL2 visualization test reporter:

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/18267/merge/testResults/webgl2playwright/index.html

bghgary · 2026-04-10T20:48:17Z

We tested WebAssembly support on some JS engines, but I don't know the status off the top of my head. Either way, we have not tested WebAssembly much in Babylon Native so more investigation is required regardless. Maybe we could use the native version directly in Babylon Native? We have similar questions for Draco and KTX support.

raymondyfei · 2026-04-10T22:38:38Z

I also believe wasm is restricted on iOS unless it is in the browser

We've tested this for iOS 18 (Safari), and the SPZ module works. I'm not sure about other WASM features, though.

raymondyfei · 2026-04-10T22:47:21Z

We tested WebAssembly support on some JS engines, but I don't know the status off the top of my head.

I did some searching, and as of 2024, 99% of tracked browsers support WebAssembly 1.0 Wikipedia, and 2024 saw the last major holdout — Safari — add Tail Calls and Garbage Collection, completing cross-browser coverage. Uno Platform Note that Safari on iOS has supported Wasm since iOS 11, not iOS 15 (iOS 15 added improvements, not initial support). Even the extended 2.0 features already exceed 90% browser coverage. Wikipedia

Maybe we could use the native version directly in Babylon Native?

Perhaps this makes both proposed mitigations compelling: a native fallback for the shrinking pool of unsupported platforms, or, simpler still, feature-flagging WASM-dependent capabilities in Babylon Native when running on unsupported kernels?

Popov72 · 2026-04-11T08:55:05Z

/azp run

azure-pipelines · 2026-04-11T08:55:15Z

Azure Pipelines successfully started running 1 pipeline(s).

bjsplat · 2026-04-11T08:57:08Z

Reviewer - this PR has made changes to one or more package.json files.

bjsplat · 2026-04-11T09:16:16Z

Interaction tests

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/18267/merge/testResults/interactionplaywright/index.html

bjsplat · 2026-04-11T09:31:45Z

WebGL2 visualization test reporter:

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/18267/merge/testResults/webgl2playwright/index.html

bjsplat · 2026-04-11T09:32:53Z

Visualization tests for WebGPU

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/18267/merge/testResults/webgpuplaywright/index.html

Raymond Fei added 6 commits April 7, 2026 14:11

replace the SPZ loader with the WASM package

a06fb4c

perf opt

69be098

bump SPZ version

7914101

Merge branch 'master' into yfei/spz_wasm_loader

42a01ec

bump SPZ version

32aff3a

fix endings

1f49393

sebavan requested a review from CedricGuillemet April 9, 2026 22:20

Add 4th-order SH loading and rendering

0d6451c

raymondyfei changed the title ~~feat(SPLAT): Replace manual SPZ loader with NianticLabs WASM implementation~~ feat(SPLAT): Replace manual SPZ loader with NianticLabs WASM implementation and enable 4-th order spherical harmonics Apr 10, 2026

minor

37d11da

add unit tests for SPZ and 4-th order SHs

f431b32

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