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iosvisionosreality-composer-pro

VisionOS: Reduce building time of rkassets package

we have a new VisionOS project, our reality composer pro package takes more than 10 minutes to build from a clean build.

We are following all the Apple guidelines to maintain a good performances in app. Unfortunately we couldn't find any guidelines about the project setup and building performances.

What would be the best approach to speed up the building time? Is Modularisation a good option? Did you find any trick to make it faster?

Solution

  • Building time, loading time and performance of AR/VR assets

    Many factors can affect building time, loading time and performance of your app. However, the main rule is – the larger your app, the longer it will take to compile. The loading and compiling speed of app is undoubtedly influenced by the number of RCP scenes, hi-rez polygonal geometry, Pixar's USDZ variants, PBR shaders, textures, asset animation, physics, spatial sounds, lighting, particles, video, etc. Developers always want to "turn all the knobs to the maximum" in AR app, but they always need to maintain a balance between the visual representation of AR scene and the real capabilities of the hardware and software. Below I want to list a few important points that you need to pay attention to when creating assets for iOS, visionOS and macOS apps in RealityKit 4.0.

    Option Value
    The ultimate number of polygons in RealityKit's Scene iOS 100K / visionOS 200K
    What file format loads models faster? .reality, (in lesser extent .usdz)
    Acceptable resolution of JPG and PNG textures 2048 x 2048, (1024 x 1024 better)
    Acceptable number of MaterialX shaders in scene as little as possible
    Acceptable number of PBR shaders in scene as little as possible
    Is it good to use transparency in textures? yes, if very moderately
    What is the best shadow type for RealityKit? fake and baked shadows
    What's the best codec for RGBA video in AR? HEVC with Alpha
    How much character animation should a scene contain? moderate amount
    How much rigid body physics should a scene contain? moderate amount

    Honestly speaking, without changing any of the above in your app, there is little you can do to speed up a building time (if you build it on Mini or on Air). You will definitely need a Mac Pro to develop multi-level hi-rez games, because the number of build iterations will be uncountable. It makes no sense to compare a top Mac Pro and a weak laptop – compile time on Mac Pro will be significantly faster. Besides, compile time is negatively affected by a small amount of RAM, and you shouldn't compile in Debug Mode. However, in the case of 10-minutes-compile-time on your M1 machine, it's worth starting with textures. Ask yourself a few questions:

    • how many models in your project use USDZ variants?
    • how many textures are there in the project?
    • what is their resolution?
    • does each texture have 72 ppi ?
    • is it better to use bake textures for Unlit shader in a scene?
    • what's a color depth in your textures – 8-bit vs 16-bit?
    • do textures use a compression?
    • do they use the same color space and profile?
    • do you use procedural textures?
    • are there mostly square textures?
    • are you using 3-channel or 4-channel textures?
    • is it possible to avoid using the alpha where applicable?
    • what file format do textures use?
    • is it possible to combine several textures into one?
    • does textures' resolution use the power of 2 principle?