gsplat-unity

Gsplat

A Unity package for rendering 3D Gaussian Splatting (3DGS). Supports Unity 2021 and later.

The 3DGS rendering pipeline design of this package is inspired by PlayCanvas, which treats 3DGS objects similarly to transparent meshes that use a custom shader. With this approach, only an additional sorting pass needs to be inserted into each camera's command buffer. This design makes it easier to integrate 3DGS rendering into an existing pipeline, allows the draw calls for 3DGS objects to be correctly inserted into the existing rendering queue for transparent meshes (based on their bounding boxes), rather than rendering all 3DGS objects to a separate render texture as is done in aras-p/UnityGaussianSplatting.

That sounds great, but at what cost?

Most 3DGS assets are trained in Gamma space, following the official implementation. This means that the alpha blending for the Gaussians is also performed in Gamma space. Since there is no longer an additional render texture that would allow us to convert the color space after the alpha blending of 3DGS, you must ensure your project's color space (Edit > Project Settings > Player > Other Settings > Rendering > Color Space) is set to "Gamma" for the 3DGS assets to be rendered correctly (be aware that HDRP doesn't support Gamma mode). For projects using a linear color space, you must retrain the 3DGS asset with linear-space images. While this plugin offers a Gamma To Linear option as a workaround, converting the color space before alpha blending leads to incorrect results and will lower the 3DGS rendering quality.

Highlights

• Supports Built-in Render Pipeline (BiRP), URP and HDRP

• Gaussians can be correctly blended with transparent meshes based on their bounding boxes

• Supports reading & rendering PLY files with SH degrees 0-3

• Supports SPZ versions 1-4 with SH degrees 0-4

• Supports orthographic projection

• Compatible with MSAA

• Compatible with XR

  • XR Render Mode	BiRP	URP	HDRP
    Multi-pass	✓	✓	✗
    Single Pass Instanced	✗	✓	✗

• Cutouts to edit Gaussians Dynamically

• Supports global sorting

Platform Compatibility

The sorting pass, built upon b0nes164/GPUSorting, requires wave / subgroups operations which are only available in D3D12, Metal or Vulkan graphics APIs. WebGPU supports the subgroup operations but Unity has not implemented it. Anything using other graphics APIs will not work. I have only tested on Windows, Mac and Android, but the compatibility of this package should be similar to aras-p/UnityGaussianSplatting.

Usage

Install

After cloning or downloading this repository, open your Unity project (or create a new one). Navigate to Window > Package Manager, click the + button, select Install package from disk..., and then choose the package.json file from this repository.

Setup

First, ensure your project is using a supported Graphics API. For Windows: in Edit > Project Settings > Player > Other Settings, uncheck Auto Graphics API for Windows. Then, in the Graphics APIs for Windows list, add Vulkan or Direct3D12 and remove any other options. Unity will require a restart to switch the Graphics API. You may need to perform similar steps for other platforms.

Note that for Android, you also need to uncheck Apply display rotation during rendering in Player > Settings for Android > Other Settings > Vulkan Settings, as this package currently does not support rendering in the native display orientation.

The next steps depend on the Render Pipeline you are using:

• BiRP: Does not need any extra setup.
• URP: Add Gsplat URP Feature to the URP renderer settings.
  • Find the Universal Renderer Data your project is using (this will default to Assets/Settings/PC_Renderer in a new URP project), click the Add Renderer Feature button, and choose Gsplat URP Feature.
  • If you are using Unity 6 or later, the Render Graph "Compatibility Mode" in URP settings must be turned off! This is off by default in new URP projects.
• HDRP: Add Custom Pass volume object in your scene and a Gsplat HDRP Pass entry to it. The injection Point should be set to Before Transparent.

Import Assets

Copy or drag & drop the PLY/SPZ file anywhere into your project's Assets folder. The package will then automatically read the file and import it as a derived class of Gsplat Asset. The package supports two compression modes for the asset: Uncompressed and Spark (packed). The default mode is Spark, which is inspired by spark.js. You can change the compression mode in the inspector of the imported Gsplat Asset.

The Opacity Prune Threshold import option removes splats whose opacity (after sigmoid) is below the threshold at import time. Since overdraw of many overlapping translucent splats is the main rendering cost of Gaussian Splatting, pruning nearly transparent splats can significantly improve frame rate, and also reduces memory usage and load time. Set the slider in the inspector of the imported asset and press Apply to reimport; the Console then logs how many splats were pruned (e.g. [Gsplat Import] scene.ply: pruned N / M splats (x.x%)). Start around 0.01–0.05 and increase while checking the visual result (thin fog-like details disappear first — as a reference, a threshold of 0.05 removed about 40% of the splats on one of our scans with little visible change). Setting it back to 0 and reimporting fully restores the original data. Currently only supported for .ply import.

Add Gsplat Renderer

Create or choose a game object in your scene, and add the Gsplat Renderer component on it. Point the Gsplat Asset field to one of your imported Gsplat Assets. Then it should appear in the viewport.

The SH Degree option sets the order of SH coefficients used for rendering. The final value is capped by the Gsplat Asset's SH Bands.

The Gamma To Linear option is offered as a workaround to render Gamma Space Gsplat Assets in a project using the Linear Space. This will degrade the rendering quality, so changing the color space of the project or retraining the 3DGS asset is the recommended approach. If your project uses a linear color space and you do not wish to retrain your 3DGS assets, it is recommended to use aras-p/UnityGaussianSplatting.

The Brightness option allows post-hoc scaling of the Gsplat Asset's brightness. This is functional regardless of color space choices, but will degrade quality if the project and assets are in Gamma Space. This can be most smoothly controlled via the Log Brightness slider.

The Async Upload option enables streaming data from RAM to VRAM, which can help reduce lags when loading the GsplatRenderer or setting its enable property to true. When enabled, the renderer can optionally draw before upload completes (Render Before Upload Complete), which will render the asset with whatever data has been uploaded so far.

Additional Documentation

• Implementation Details

Project Using Gsplat

• HiFi-Human/DynGsplat-unity - A Unity package for rendering and playing dynamic gaussian splatting sequences

License

This project is released under the MIT license. It is built upon several other open-source projects:

• playcanvas/engine, MIT License (c) 2011-2024 PlayCanvas Ltd
• aras-p/UnityGaussianSplatting, MIT License (c) 2023 Aras Pranckevičius
• b0nes164/GPUSorting, MIT License (c) 2024 Thomas Smith
• sparkjsdev/spark, MIT License (c) 2025 WORLD LABS TECHNOLOGIES, INC.
• nianticlabs/spz, MIT License (c) 2024 Niantic Labs
• oleg-st/ZstdSharp, MIT License (c) 2021 Oleg Stepanischev