Cycles renders invisible faces or Blender does not display them #40125

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Maverick · 2014-05-10T12:44:52+02:00

Maverick commented

2014-05-10 12:44:52 +02:00

System Information
win7 64 i7 gtx titan

Blender Version
blender-2.70-4a1b877-win64

Short description of error
Backface culling is disabled and double sided enabled however you cannot see the faces in edit mode or object mode.
Normals appear on these invisible faces though.

Exact steps for others to reproduce the error
Switch to Cycles rendered mode and you will see some faces covering the window.
(see attached file)

invisible_faces.blend

**System Information** win7 64 i7 gtx titan **Blender Version** blender-2.70-4a1b877-win64 **Short description of error** Backface culling is disabled and double sided enabled however you cannot see the faces in edit mode or object mode. Normals appear on these invisible faces though. **Exact steps for others to reproduce the error** Switch to Cycles rendered mode and you will see some faces covering the window. (see attached file) [invisible_faces.blend](https://archive.blender.org/developer/F88137/invisible_faces.blend)

Maverick commented

2014-05-10 12:44:52 +02:00

Changed status to: 'Open'

Maverick commented

2014-05-10 12:44:52 +02:00

Added subscriber: @dragostanasie

Maverick commented

2014-05-10 12:47:09 +02:00

![1.png](https://archive.blender.org/developer/F88138/1.png) ![2.png](https://archive.blender.org/developer/F88140/2.png)

Willi commented

2014-05-10 14:41:59 +02:00

Added subscriber: @willi-2

Willi commented

2014-05-10 14:41:59 +02:00

You've created several concave ngons here. I suggest: go to edit mode, select all and press Ctrl+T (triangulate). Now you see what's actually wrong. So I suggest you clean-up the mesh first, then try again. You have some double edges, too.

The problem I see with Blender is only that concave ngons in solid shading mode in the view port are not displayed as when rendered, however this can be a known limitation (let's see what a dev says about it).

You've created several concave ngons here. I suggest: go to edit mode, select all and press Ctrl+T (triangulate). Now you see what's actually wrong. So I suggest you clean-up the mesh first, then try again. You have some double edges, too. The problem I see with Blender is only that concave ngons in solid shading mode in the view port are not displayed as when rendered, however this can be a known limitation (let's see what a dev says about it).

Willi commented

2014-05-10 14:58:52 +02:00

For example:
invisible_faces_new.blend

Only use the mesh. UVmap has to be recreated.

For example: [invisible_faces_new.blend](https://archive.blender.org/developer/F88161/invisible_faces_new.blend) Only use the mesh. UVmap has to be recreated.

Maverick commented

2014-05-10 18:09:44 +02:00

I have a better example, minimal. This just renders badly. There seems to be a problem with the ngons.

These objects have been imported and not created by hand.

faces_bug.blend

I have a better example, minimal. This just renders badly. There seems to be a problem with the ngons. These objects have been imported and not created by hand. [faces_bug.blend](https://archive.blender.org/developer/F88219/faces_bug.blend)

Willi commented

2014-05-10 19:41:58 +02:00

I do not see a problem with this file.

Object mode:

Edit mode:

Rendered:

Note, I'm using CPU rendering.

I do not see a problem with this file. Object mode: ![Bild_323.JPG](https://archive.blender.org/developer/F88237/Bild_323.JPG) Edit mode: ![Bild_324.JPG](https://archive.blender.org/developer/F88239/Bild_324.JPG) Rendered: ![Bild_325.JPG](https://archive.blender.org/developer/F88241/Bild_325.JPG) Note, I'm using CPU rendering.

Brecht Van Lommel was assigned by Thomas Dinges

2014-05-11 10:42:49 +02:00

Thomas Dinges commented

2014-05-11 10:42:49 +02:00

Added subscriber: @ThomasDinges

Thomas Dinges commented

2014-05-11 10:42:49 +02:00

GPU rendering fails in the Viewport, CPU works fine here.

Switching to "Static BVH" type fixes it for GPU.

GPU rendering fails in the Viewport, CPU works fine here. Switching to "Static BVH" type fixes it for GPU.

Brecht Van Lommel commented

2014-05-12 15:02:11 +02:00

Changed status from 'Open' to: 'Archived'

Brecht Van Lommel closed this issue

2014-05-12 15:02:11 +02:00

Brecht Van Lommel commented

2014-05-12 15:02:11 +02:00

There's two different problems here. The first one is because of problematic ngons.

The other is because of float precision issues, due to the polygon being quite far from the origin, which gets worse due to imprecision of instancing. We'd like to improve precision here but this is not considered a bug at the moment.

There's two different problems here. The first one is because of problematic ngons. The other is because of float precision issues, due to the polygon being quite far from the origin, which gets worse due to imprecision of instancing. We'd like to improve precision here but this is not considered a bug at the moment.

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Cycles renders invisible faces or Blender does not display them #40125