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Wrong transparent node setup in GLTF import
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Description

System Information
Operating system: Linux and Windows
Graphics card: NVidia GTX 1060 6GB

Blender Version
Broken: 2.80, a3b88c917299, 2019-04-10

Short description of error
The GLFT/GLB importer has wrong transparency factor on transparent materials for Transparent BSDF

Exact steps for others to reproduce the error
My usecase is a bit more complex since I generate my glb files from a threejs scene. But steps to reproduce are:

  • create an object3D in threejs with this material MeshStandardMaterial( { color: new THREE.Color(0xDDDDDD), transparent: true, opacity: 0.2, shininess: 10000, transparencyMode: 2 })
  • export a glb file
  • open a new scene in blender 2.80
  • import the glb

The material nodes are setup correctly but the factor for the mix shader should take the opacity value of the glb material for the transparent BSDF node.

Details

Type
Bug

Event Timeline

Brecht Van Lommel (brecht) edited projects, added Add-ons; removed BF Blender.

Please attach the .glb file to reproduce the issue.

Here is the glb. You need to scale it to 0.01 after import since our measurement in the threejs scene is in cm, not meters.
Besides: The UV maps are messed up, too. But I'm still trying to find our where the problem is.

Julien DUROURE (julien) lowered the priority of this task from Needs Triage by Developer to Needs Information from User.Apr 15 2019, 11:38 AM

I not agree with the analysis.
Factor of the mixShader node will do the following : 1 for transparent, 0 for opaque.
The Add node is used as factor. So if you have an alpha of 0.2, you have to set factor to 0.8.
The second image is wrong, because add 0.8 and 0.2 --> full transparent because of factor of 1.0

Note that Principled shader now has an Alpha value too…

Anyway, More than a week without reply or activity. Due to the policy of the tracker archiving for until required info/data are provided.