Improving Game Performance: How to Reduce FBX File Sizes in Unity

Posted on 07.06.2023 — Author: @Mentolatux

FBX, a versatile 3D model format, is commonly utilized in gaming, animation, and film due to its capacity to support various data types, such as geometry, textures, lighting, and energy. However, game developers often face challenges with the size of FBX files, which can be pretty significant. These substantial file sizes can lead to issues like extended loading times, increased memory usage, and an overall decline in performance, particularly on resource-limited platforms like mobile devices or WebGL.

Unity, a game engine with widespread usage, offers a variety of methods to enhance performance by optimizing FBX assets.

One such method is mesh compression.

Unity's Mesh Compression feature allows the ability to regulate the amount of data used to store your 3D models' details, directly influencing the size of your FBX files. By leveraging algorithms, mesh compression approximates your mesh data and decreases the bit count required to represent it.

Unity provides four options for mesh compression: Off, Low, Medium, and High. Higher compression results in smaller file sizes but compromises the model's visual quality. Therefore, it's crucial to strike a balance between performance and quality. A low or medium compression level frequently reduces file sizes without noticeably impacting visual quality.

Import Settings

Additional import settings can also aid in minimizing your FBX file sizes, such as:

Read/Write Enabled: By disabling this setting, Unity can remove the mesh data copy from system memory once uploaded to the GPU, reducing memory usage by half. However, this setting must remain enabled if your script requires runtime mesh data access. Optimize Mesh Data: Enabling this setting discards unnecessary data from the mesh not needed for the assigned material, potentially shrinking the file size. Mesh Compression: As previously mentioned, you can regulate the compression level applied to the mesh, potentially causing a significant reduction in file size, especially for complex meshes. Blend Shapes: Disable this option if your model doesn't utilize blend shapes to prevent unneeded data storage. Animation Compression: If your FBX file incorporates animations, consider applying animation compression to reduce the size of your animation data significantly.

Asset Bundles and Addressable Assets

Unity's Asset Bundles and Addressable Assets system present another effective solution for optimizing your game's loading and memory usage. Rather than loading all assets simultaneously, this system enables you to organize and load only the required support for a specific scene or gameplay context, reducing memory usage and potentially the size of your game's binary.

Asset Bundles can group and load assets during runtime, lessening your game's initial load time and memory usage. Likewise, the Addressable Assets system allows assets to be loaded using an address, offering more dynamic and efficient asset loading.

Mesh Simplification

One more method for reducing FBX file sizes involves simplifying the mesh. Various third-party tools can decrease a mesh's polygon count without significantly impacting its visual quality. By reducing the complexity of your 3D models, you can substantially shrink the size of the FBX files and enhance your game's runtime performance.

In conclusion, while FBX files offer a robust and flexible format for 3D model data, they also introduce challenges with size and performance. Unity provides various built-in tools and settings to combat these challenges, including mesh compression, asset bundles, and import setting optimizations. Furthermore, developers can utilize third-party tools for mesh simplification and file size reduction. Combining these strategies enables the creation of efficient, high-performance games, even on resource-limited platforms.

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