Vertex-per-face normals generated by auto-smooth are not exported by collada exporter. #44900

New Issue

Drongle McMahon · 2015-05-30T23:12:35+02:00

Drongle McMahon commented

2015-05-30 23:12:35 +02:00

System: windows 7, gtx670
Blendr version: 2.74 dc15860 (and earlier) win64

Description: Vertex-per-face normals generated by auto-smooth are not exported by collada exporter.

Reproduction: File auto_smooth_export.blend: Make an 8-sided cylinder with triangle fan caps, with smooth shading, with auto-smooth active and with auto-smooth angle set to 80 degrees. This produces a smooth shaded cylinder with sharp edges around the caps. Duplicate the cylinder and name them "Source" and "Target". Add a Data Transfer modifier to "Target", using "source" as the source with evaluation in object spaces, transferring (replace) custom normals from "Nearest corner and Best Matching Face normal". Note that the vertex-per face normals displayed in the 3D view appear identical in "Target" and source both before and after adding the modifier. They are all either parallel with or perpendicular to the Z axis. Export each object separately with the Collada exporter checking only "Apply Modifier" and "Selection Only" options.

The file exported from "Source" has the smooth shading vertex normals unaffected by auto-smooth (i.e. those in the blue line vertex normal display). The file exporter from "Target" has the Vertex-per-face normals (purple lines). "Target" still has the transferred custom normals if its auto-smooth angle is set to 180 degrees. The distinction is immediately clear by inspecting the Z components of the normals, and can be visualised by importing into other software.

I don't know whether the internal representation of the "vertex-per-face normals" generated by auto-smooth is the same as that of the "custom normals" transferred by the Data Transfer modifier. Therefore I don't really know whether the fact that they are not exported is intended or is a bug. However, I did expect them to be exported, given their similar representation in the UI, and it would certainly be useful if they were. There is, however, the work-around by copying the normals from the duplicate, as illustrated here. So whether this is something that needs to be corrected or not is entirely up to the developers, depending on intent and practicability. I offer my apologies if this should be condidered as a feature request rather than as a bug.

auto_smooth_export.blend

System: windows 7, gtx670 Blendr version: 2.74 dc15860 (and earlier) win64 Description: Vertex-per-face normals generated by auto-smooth are not exported by collada exporter. Reproduction: File auto_smooth_export.blend: Make an 8-sided cylinder with triangle fan caps, with smooth shading, with auto-smooth active and with auto-smooth angle set to 80 degrees. This produces a smooth shaded cylinder with sharp edges around the caps. Duplicate the cylinder and name them "Source" and "Target". Add a Data Transfer modifier to "Target", using "source" as the source with evaluation in object spaces, transferring (replace) custom normals from "Nearest corner and Best Matching Face normal". Note that the vertex-per face normals displayed in the 3D view appear identical in "Target" and source both before and after adding the modifier. They are all either parallel with or perpendicular to the Z axis. Export each object separately with the Collada exporter checking only "Apply Modifier" and "Selection Only" options. The file exported from "Source" has the smooth shading vertex normals unaffected by auto-smooth (i.e. those in the blue line vertex normal display). The file exporter from "Target" has the Vertex-per-face normals (purple lines). "Target" still has the transferred custom normals if its auto-smooth angle is set to 180 degrees. The distinction is immediately clear by inspecting the Z components of the normals, and can be visualised by importing into other software. I don't know whether the internal representation of the "vertex-per-face normals" generated by auto-smooth is the same as that of the "custom normals" transferred by the Data Transfer modifier. Therefore I don't really know whether the fact that they are not exported is intended or is a bug. However, I did expect them to be exported, given their similar representation in the UI, and it would certainly be useful if they were. There is, however, the work-around by copying the normals from the duplicate, as illustrated here. So whether this is something that needs to be corrected or not is entirely up to the developers, depending on intent and practicability. I offer my apologies if this should be condidered as a feature request rather than as a bug. [auto_smooth_export.blend](https://archive.blender.org/developer/F182151/auto_smooth_export.blend)

Drongle McMahon commented

2015-05-30 23:12:35 +02:00

Changed status to: 'Open'

Gaia Clary was assigned by Drongle McMahon

2015-05-30 23:12:35 +02:00

Drongle McMahon commented

2015-05-30 23:12:35 +02:00

Added subscriber: @Drongle