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Windows Mixed Reality Asset Converter

A command line tool to convert core GLTF 2.0 for use in the Windows Mixed Reality home, following the published documentation.

Note that this tool does not enforce any limits specified in the documentation (polygon count, texture size, etc.), so you might still encounter issues placing models if you do not conform to those limits.

Usage

WindowsMRAssetConverter <path to GLTF/GLB>

Optional arguments

  • -o <output file path>

    • Specifies the output file name and directory for the output GLB.
    • If the file is a GLB and the output name is not specified, the tool defaults to the same name as input + "_converted.glb".

  • -platform <all | desktop | holographic>

  • -min-version <1709 | 1803 | latest>

    • Default: 1709
    • Specifies the minimum version of Windows 10 supported by this asset.
    • The current options are 1709 (Fall Creators Update) and 1803 (Spring Creators Update), as well as latest which is currently the same as 1803.
    • Supporting Windows 10 version 1709 results in assets with a larger file size. If your app is compatible with Windows 10 1803+ only, it is recommended to set -min-version 1803.
    • This setting does not have any effect on the Holographic platform.

  • -lod <path to each lower LOD asset in descending order of quality>

    • Specifies a list of assets that represent levels of detail, from higher to lower, that should be merged with the main asset and used as alternates when the asset is displayed from a distance (with limited screen coverage).

  • -screen-coverage <LOD screen coverage values>

    • Specifies the maximum screen coverage values for each of the levels of detail, according to the MSFT_lod extension specification.

  • -share-materials

    • If enabled, creates assets that share materials between different levels of detail.
    • This assumes all LOD documents use the same indices for each material, and uses the textures from the most detailed level.

  • -temp-directory <temporary folder>

    • Default: system temp folder for the user
    • Allows overriding the temporary folder where intermediate files (packed/compressed textures, converted GLBs) will be placed.

  • -max-texture-size <Max texture size in pixels>

    • Default: 512
    • Allows overriding the maximum texture dimension (width/height) when compressing textures. The recommended maximum dimension in the documentation is 512, and the allowed maximum is 4096.

  • -replace-textures

    • If enabled, replaces all textures with their DDS compressed equivalents during the compression step.
    • This results in a smaller file size, but the resulting file will not be compatible with most glTF viewers.

Example

WindowsMRAssetConverter FileToConvert.gltf -o ConvertedFile.glb -platform all -lod Lod1.gltf Lod2.gltf -screen-coverage 0.5 0.2 0.01

The above will convert FileToConvert.gltf into ConvertedFile.glb in the current directory.

Pipeline overview

Each asset goes through the following steps when converting for compatibility with the Windows Mixed Reality home:

  1. Conversion from GLB - Any GLB files are converted to loose glTF + assets, to simplify the code for reading resources
  2. Texture packing - The textures that are relevant for the Windows MR home are packed according to the documentation using the MSFT_packing_occlusionRoughnessMetallic and MSFT_packing_normalRoughnessMetallic extensions as necessary
  3. Texture compression - All textures that are used in the Windows MR home must be compressed as DDS BC5 or BC7 according to the documentation. This step also generates mip maps for the textures, and resizes them down if necessary
  4. LOD merging - All assets that represent levels of detail are merged into the main asset using the MSFT_lod extension
  5. GLB export - The resulting assets are exported as a GLB with all resources. As part of this step, accessors are modified to conform to the glTF implementation notes in the documentation: component types are converted to types supported by the Windows MR home, and the min and max values are calculated before serializing the accessors to the GLB

Additional resources