Editor: Make IOR configurable. #28028
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| @@ -111,6 +111,11 @@ function SidebarMaterial( editor ) { | |||
| const materialReflectivity = new SidebarMaterialNumberProperty( editor, 'reflectivity', strings.getKey( 'sidebar/material/reflectivity' ) ); | |||
| container.add( materialReflectivity ); | |||
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| // ior | |||
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| const materialIOR = new SidebarMaterialNumberProperty( editor, 'ior', strings.getKey( 'sidebar/material/ior' ), [ 1, 2.333 ], 3 ); | |||
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The documentation states that MeshPhysicalMaterial.ior has a range of [1, 2.333]. However, there are glTF assets with a higher IOR value. E.g. https://github.com/KhronosGroup/glTF-Sample-Assets/tree/main/Models/DispersionTest uses 2.42. Should we allow a higher range in the editor e.g. [ 1, 3 ]?
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Do we know where that range come from? The glTF docs don't seem to specify an upper bound:
Valid values for ior are numbers greater than or equal to 1. In addition, a value of 0 is allowed.
But I agree that a max of something like 3 is good enough.
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glTF allows IOR values of 0, disallows values between 0 and 1 (exclusive), and allows 1 to infinity (inclusive).
2.42 is a typical value for diamonds according the KHR_materials_ior spec, but values >2 are otherwise physically unusual. Occasionally I see glTF files containing ior=0 or ior=1000+, these are not physically-plausible but are occasionally useful to give ...
"...full weight to layer, i.e., the Fresnel term evaluates to 1 independent of the view or light direction. It is useful in combination with KHR_materials_specular to seamlessly support the specular-glossiness workflow."
In other words, it's a trick that is very useful when converting materials from the spec/gloss PBR workflow to the metal/rough workflow.
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Thanks for the feedback. I'll merge the PR with the current settings so it aligns to the documentation. But it seems we should reconsider the current IOR range and think about adapting the glTF policy.
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If we need an example with higher IOR, a good way to test is to start with this model:
It shows two bottles, one metal/rough and one spec/gloss. We don't support spec/gloss, so the latter will appear white in the editor:
If you convert the second bottle to metal/rough...
gltf-transform metalrough input.glb output.glb
... then the second bottle will include a material with ior=1000, and both bottles should appear identical:
Related issue: -
Description
This PR makes sure the
iorproperty ofMeshPhysicalMaterialcan directly be configured and not just indirectly viareflectivity.