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GLB Export

Basic GLB Export​

Requirements​

  • one uv map
  • one material for all diffuse, one material per any GLSL shaders. For example, if there is a sword with the blade intended to be a shader, there would be one material which contains the texture information of the handle/hilt/etc, and one separate material for the blade marked to be overwritten by the GLSL shader in-engine.
  • make sure to have a principled bsdf material setup
    • diffuse texture should be connected to color input and colorspace set to srgb
    • occlusion/metalness/roughness texture should have a "seperate rgb"" attached to it and each R G B channel should be connected to the appropriate metalness , roughness inputs as well as a gltf occlusion node that would be appended from a seperate blend file. colorspace should be set to non color
    • normal map texture should connect to a normal map node and then to the normal input of the principled bsdf shader. colorspace is set to non-color
  • optimized mesh
  • any animations you wish to include with the model should be pushed down to the nla editor as strips

Step by Step​

  • select object
  • go to File
  • select Export
  • select GLTF 2.0 (.glb/.gltf)
  • choose remember settings
  • input appropriate setting in the right hand settings panel also accessed via the gear icon
  • choose appropriate filename
  • click export

GLTF Settings​

In the gltf export menu to the right there are several tabs to go through and set options on

  • Include
    • selected objects
  • Transform
    • +Yup
  • Geometry
    • Apply Modifiers
    • Uv's
    • Normals
    • Materials - Export
    • Images - Jpeg Format (set this to automatic if you wish to retain your iamges as png)
    • Compression - enable if draco compression is supported
  • Animation
    • you can leave these as they if you have animations to export
    • you can disable these if you are exporting a static asset

Ktx2 Texture Compression​

Textures can take up a lot of space and make world loading slower for less powerful machines. Ktx2 texture compression significantly reduces the file size for pre-existing GLB files without having much of an affect on the quality of the models. Follow these steps to compress the models:

gltfpack -i inputfilename.glb -cc -tc -o outputfilename.glb

Video Tutorial:​

https://youtu.be/vlCJYbp4bi8

Draco mesh Compression​

The models having draco mesh can have issues with the previous (meshoptimizer) ktx2 compression method. For such models, this method is helpful.

  • Install the tool using this command:

     npm install --global @gltf-transform/cli

  • once installed, Use this command to compress using etc1s:

    gltf-transform etc1s inputmodel.glb modeletc1s.glb

  • After that use this command for draco compression:

    gltf-transform draco modeletc1s.glb modeletc1sdraco.glb

For reference, visit this site: https://gltf-transform.donmccurdy.com/cli.html