FBX Runtime Exporter documentation

The FBX Runtime Exporter plugin allows you to seamlessly export objects from your Unity scene into FBX format, both at runtime and within the Unity Editor.

What gets exported

Nothing else is captured: lights, cameras, particles, physics colliders, LOD groups and scripts are outside what an FBX file carries here.

Platforms and requirements

• Unity version: 2021.3 or newer.
• Supported platforms: Windows, Linux — the Editor on either, and standalone builds for either.

Export from the Unity Editor

Right-click the object in the Hierarchy window and choose Export → FBX.

The FBX Exporter window opens with that object as its subject. Set the options, press Export, and the window closes and refreshes the asset database.

Materials that ship with the sample scene are authored for the built-in render pipeline. In a URP or HDRP project they render magenta, and the plugin offers to convert them the first time it loads — see Sample materials in URP and HDRP.

Export from code

The same class does the work in the Editor and in a build:

using UnityEngine;
using DevEloop.FBXExport;

public class ExportButton : MonoBehaviour
{
    public GameObject objectToExport;

    public void OnExportClick()
    {
        if (!FbxExporter.IsFbxExportSupported)
            return;                       // not Windows or Linux

        string outputFbxPath = System.IO.Path.Combine(
            Application.persistentDataPath, objectToExport.name + ".fbx");

        FbxExporter fbxExporter = new FbxExporter();
        fbxExporter.ExportAnimations = true;
        fbxExporter.ModelScale = 100.0f;

        if (fbxExporter.ExportObjectToFbx(objectToExport, outputFbxPath))
            Debug.Log("Exported to " + outputFbxPath);
    }
}

ExportObjectToFbx(GameObject model, string outputFbxFilename) returns true on success. It creates the output directory if it is missing, and logs the reason for every failure it can detect — a missing model, an empty path, an unreadable mesh, a bone outside the exported hierarchy, an unsupported platform. The call is synchronous and does its work on the main thread, so a large character with textures will stall a frame; run it from a button, not from Update.

FbxExporter properties

An FbxExporter instance keeps no state between calls — it clears its internal tables at the start of every export — so one instance can be reused, or a new one created per export, whichever reads better.

Meshes must be readable in a build

In the Editor the plugin can read any mesh. In a build it cannot: Unity uploads mesh data to the GPU and frees the CPU copy unless the model asset has Read/Write Enabled ticked in its import settings. An unreadable mesh is skipped with

“the … mesh isn’t readable. It can’t be exported into FBX”

and the rest of the model still exports. This is the single most common surprise with runtime export, because it never appears while you are testing in the Editor. Tick Read/Write Enabled on every model you intend to export at runtime, and test in a real build.

Animation

Turn on ExportAnimations and, for every node in the exported hierarchy, the plugin collects clips from an Animation component (all of its states) and from an Animator component (all of the clips in its RuntimeAnimatorController). Each clip becomes an animation take in the FBX, named after the clip.

How the curves are produced depends on the clip and on where you are running:

Baking poses the model, samples it, and restores the original transforms and blendshape weights afterwards, so the scene is left as it was found.

Two consequences worth knowing. AnimationFps only matters when a clip is baked, and raising it makes the export longer and the file larger. And a clip that animates a node not present in the exported hierarchy is reported and skipped — if you export a child and its Animator drives bones above it, those curves have nowhere to go. Each such node produces a warning naming the clip and the path, so the console tells you exactly which ones were dropped.

Blendshape animation needs the animated node to carry a SkinnedMeshRenderer that was itself exported; a blendshape curve pointing at a node without one is skipped with a warning.

Terrain

A terrain is not a mesh, so the plugin builds one: the heightmap is resampled to a 128 × 128 grid and given the terrain’s base material. That resolution is fixed, and it is a deliberate trade — a full-resolution terrain mesh is enormous. Layer blending is not baked: the exported mesh carries the base material’s texture, not the splatmap-blended surface you see in the scene.

Two things to watch. The Terrain component has to be on the object you export — the plugin looks for it on the root you pass in, not on children — so right-click the terrain object itself. And ExportTerrainTrees instantiates every tree instance as a real GameObject before exporting; on a terrain with thousands of trees that is a slow export and a very large file. The temporary objects are destroyed once the file is written.

Materials and textures

Materials are matched by shader property name, which is why Built-In, URP and HDRP all work without configuration:

Unity stores normal maps in a packed two-channel format, so a normal map is decoded back to ordinary RGB before it is embedded — otherwise it would arrive in Blender as a blue-and-red image. Every texture is read through the GPU into a Texture2D and encoded as PNG, which means compressed, non-readable and render textures all export fine, at the cost of a full-size PNG per texture. Materials and textures are deduplicated across the whole model, so a texture shared by ten materials is embedded once.

The FBX material model has three texture slots. Metallic, smoothness, occlusion and height maps are read out of the material but have nowhere to go in the file, so plan on reconnecting those in the target application.

Sample materials in URP and HDRP

The materials in Assets/DevEloop/FbxExporter/Materials use the built-in pipeline’s Standard shader, so in a URP or HDRP project the sample scene renders magenta. The first time the plugin loads in such a project it offers to convert them; decline and it will not ask again. You can also run the conversion at any time from the main menu:

• Tools → DevEloop → FBX Exporter → Convert Sample Materials to Active Render Pipeline
• Tools → DevEloop → FBX Exporter → Convert Selected Materials to Active Render Pipeline — the same conversion for any built-in-pipeline materials you have selected in the Project window.

This affects the bundled sample assets only. The exporter itself needs no conversion — it reads every pipeline’s materials as they are.

Converting to HDRP is lossy in one respect: HDRP wants metallic, smoothness and occlusion packed into a single mask map, so separate maps cannot be carried over and only the scalar values are converted. The plugin logs a warning naming each material this applies to.

Sample scene

Assets/DevEloop/FbxExporter/Scenes/FbxExporterSample.unity has both workflows in one scene: an Export Objects button that exports at runtime through FbxExporterSample.cs, and the same objects to right-click in the Hierarchy for the Editor path. In the Editor the button opens a save dialog; in a build it writes to Application.persistentDataPath. It is the quickest way to confirm the plugin works, and a working reference for wiring the API to your own UI.

Coordinates, units and conventions

Unity is left-handed and Y-up; FBX is right-handed. The plugin mirrors the X axis of every position, rotation, vertex, normal and blendshape delta, and reverses triangle winding to match, so a model arrives in Blender or Maya oriented the way it looked in Unity rather than inside out.

Units are Unity’s: one unit exports as one FBX unit unless you set ModelScale. Most DCC tools work in centimetres, where a character exported at scale 1 arrives a hundred times too small — ModelScale = 100 is the usual fix.

Rotation is exported as quaternion curves, so an animation cannot suffer gimbal flips introduced by an Euler conversion.

Troubleshooting

Support

Include your Unity version, platform, what you exported and the full console output — the plugin logs the reason for every failure it can detect.

dev.eloop@outlook.com

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