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Double Sided #58

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mrdoob opened this Issue Aug 3, 2017 · 2 comments

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mrdoob commented Aug 3, 2017

I think double sided is currently not being exported.

screen shot 2017-08-03 at 3 00 27 pm

Files:
doublesided.zip

@UX3D-nopper UX3D-nopper added the wontfix label Aug 3, 2017

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UX3D-nopper Aug 3, 2017

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Correct, but it is not a bug.
It has been decided - in glTF 2.0 - that double sided is a material and not a mesh attribute:
https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/schema/material.schema.json
If you need double sided, please use the the glTF 2.0 PBR node groups.

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UX3D-nopper commented Aug 3, 2017

Correct, but it is not a bug.
It has been decided - in glTF 2.0 - that double sided is a material and not a mesh attribute:
https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/schema/material.schema.json
If you need double sided, please use the the glTF 2.0 PBR node groups.

@UX3D-nopper UX3D-nopper closed this Aug 3, 2017

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emackey Aug 4, 2017

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Yep. Also, Blender's use of "Double Sided" here refers to what OpenGL 1.0 calls TWO_SIDED_LIGHTING, which is a bit of fixed-function math that is replaced by programmable shaders in WebGL. It was decided in glTF 2.0 that the double-sided flag refers specifically to backface culling, not two-sided lighting, and that glTF materials (when not culled) always use two-sided lighting.

Blender has a backface culling flag, but it refers to individual viewports, not individual materials, so doesn't translate to glTF.

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emackey commented Aug 4, 2017

Yep. Also, Blender's use of "Double Sided" here refers to what OpenGL 1.0 calls TWO_SIDED_LIGHTING, which is a bit of fixed-function math that is replaced by programmable shaders in WebGL. It was decided in glTF 2.0 that the double-sided flag refers specifically to backface culling, not two-sided lighting, and that glTF materials (when not culled) always use two-sided lighting.

Blender has a backface culling flag, but it refers to individual viewports, not individual materials, so doesn't translate to glTF.

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