Freestyle wireframe-only rendering is broken with Ztrans faces (lines disappear when Ztrans alpha and Ztrans spec are set to zero / lines behind transparent faces are not rendered / marked edges are not sometimes rendered when faces overlap) #46978

New Issue

lauri järvenpää · 2015-12-15T13:03:49+01:00

2015-12-15 13:03:49 +01:00

System Information
OSX 10.11.2 / Macbook Pro Retina 15" Mid 2014 / GeForce GT 750M

Blender Version
Broken: 2.76b (also broken in 2.76)

Short description of error
Rendering wireframes with controllable wire thickness requires using Freestyle but Freestyle requires filled faces even when rendering only edges. To only render edges and make the faces invisible one must set Ztrans alpha to zero.

When other line objects are behind line-only objects their lines are culled (however ordinary objects are rendered properly)
When both Ztrans alpha and spec are set to zero no lines are rendered
When faces overlap only some marked edges are rendered (even when faces are set to be transparent)

Exact steps for others to reproduce the error
Observe and render the attached .blend file.
freestyle-lineclipping.blend

**System Information** OSX 10.11.2 / Macbook Pro Retina 15" Mid 2014 / GeForce GT 750M **Blender Version** Broken: 2.76b (also broken in 2.76) **Short description of error** Rendering wireframes with controllable wire thickness requires using Freestyle but Freestyle requires filled faces even when rendering only edges. To only render edges and make the faces invisible one must set Ztrans alpha to zero. - When other line objects are behind line-only objects their lines are culled (however ordinary objects are rendered properly) - When both Ztrans alpha and spec are set to zero no lines are rendered - When faces overlap only some marked edges are rendered (even when faces are set to be transparent) **Exact steps for others to reproduce the error** Observe and render the attached .blend file. [freestyle-lineclipping.blend](https://archive.blender.org/developer/F268076/freestyle-lineclipping.blend)

lauri järvenpää commented

2015-12-15 13:03:49 +01:00

Changed status to: 'Open'

lauri järvenpää commented

2015-12-15 13:03:49 +01:00

Added subscriber: @hevonen

Sergey Sharybin commented

2015-12-15 14:17:50 +01:00

Added subscribers: @kjym3, @Sergey

Tamito Kajiyama was assigned by Sergey Sharybin

2015-12-15 14:17:50 +01:00

Sergey Sharybin commented

2015-12-15 14:17:50 +01:00

@kjym3, are you around to help us with freestyle? :)

Tamito Kajiyama commented

2015-12-15 14:24:28 +01:00

@Sergey Yes I am and thanks for the triage. Will look into the reported issue as soon as time permits.

Tamito Kajiyama commented

2015-12-15 16:17:44 +01:00

Freestyle requires filled faces to render lines along selected edges of the faces.

On the other hand, objects having a non-transparent material are considered a faced object (internally referred to as "vlak object" in Blender, where vlak means face in Dutch -- a terminology residual originating from the NaN era of Blender history). Freestyle ignores all objects having a transparent material and a wireframe material because they are considered not having faces.

These limitations are by design (documented so in the Blender manual) and not considered a bug. Consequently,

When both Ztrans alpha and spec are set to zero no lines are rendered

This is intended because of a non-vlak object (specifically Cube.007) due to a transparent material.

When other line objects are behind line-only objects their lines are culled (however ordinary objects are rendered properly)

Could you please specify by object name (e.g., "Cube.001") which objects the "line-only objects" are?

When faces overlap only some marked edges are rendered (even when faces are set to be transparent)

I am not sure which part of the supplied .blend file this statement actually refers to. I would appreciate it if you could elaborate it.

Notice that objects having a shadeless material are vlak objects even when they look transparent. Plus, Freestyle does not take account of face alpha transparency no matter how the transparency is specified (by materials and/or textures) and treats all faces as opaque (also documented in the manual). These features may explain what you get as a render from the demo scene.

Additional remark:

To only render edges and make the faces invisible one must set Ztrans alpha to zero.

You can obtain onnly Freestyle lines by turning off the Solid toggle in the render layer options. You don't really need to rely on a transparent material.

Freestyle requires filled faces to render lines along selected edges of the faces. On the other hand, objects having a non-transparent material are considered a faced object (internally referred to as "vlak object" in Blender, where vlak means face in Dutch -- a terminology residual originating from the NaN era of Blender history). Freestyle ignores all objects having a transparent material and a wireframe material because they are considered not having faces. These limitations are by design ([documented so ](https://blender.org/manual/render/freestyle/introduction.html#known-limitations) in the Blender manual) and not considered a bug. Consequently, > * When both Ztrans alpha and spec are set to zero no lines are rendered This is intended because of a non-vlak object (specifically Cube.007) due to a transparent material. > * When other line objects are behind line-only objects their lines are culled (however ordinary objects are rendered properly) Could you please specify by object name (e.g., "Cube.001") which objects the "line-only objects" are? > * When faces overlap only some marked edges are rendered (even when faces are set to be transparent) I am not sure which part of the supplied .blend file this statement actually refers to. I would appreciate it if you could elaborate it. Notice that objects having a shadeless material are vlak objects even when they look transparent. Plus, Freestyle does not take account of face alpha transparency no matter how the transparency is specified (by materials and/or textures) and treats all faces as opaque (also [documented ](https://blender.org/manual/render/freestyle/introduction.html#known-limitations) in the manual). These features may explain what you get as a render from the demo scene. Additional remark: > To only render edges and make the faces invisible one must set Ztrans alpha to zero. You can obtain onnly Freestyle lines by turning off the Solid toggle in the render layer options. You don't really need to rely on a transparent material.

lauri järvenpää commented

2015-12-15 17:08:49 +01:00

Ah okay, thanks.

In the middle example cube.002 clips lines from cube.003 but cube.006 is rendered on the background without clipping. So Freestyle ignores transparencies but faces themselves are rendered via Blender internal and have proper transparency and Freestyle's clipped edges are just composited on top.

Overlapping edge rendering is visible at the lower right corner of the render (plane.009), on it's left is a ordinary wireframe for comparison. Some edges are not rendered (eg. low right corner edge is cut short). This is apparently also because Freestyle only thinks about faces and therefore there is z-test(?) which kills some lines with a competing face. Not a real problem in this case as I can just use hidden lines for a 2d object.

In my case I'm rendering BI shaded objects with multiple Freestyle wireframe overlays (for multiple colors) so I need solids. There was not enough layers in Blender to trivially make render passes via layers so I was just aiming for the easiest way to get the results.

Is it impossible to render cube.003 so that it's lines would not be clipped by cube.002 without using render passes (per object visible lines instead of full render visible lines)?

Ah okay, thanks. In the middle example cube.002 clips lines from cube.003 but cube.006 is rendered on the background without clipping. So Freestyle ignores transparencies but faces themselves are rendered via Blender internal and have proper transparency and Freestyle's clipped edges are just composited on top. Overlapping edge rendering is visible at the lower right corner of the render (plane.009), on it's left is a ordinary wireframe for comparison. Some edges are not rendered (eg. low right corner edge is cut short). This is apparently also because Freestyle only thinks about faces and therefore there is z-test(?) which kills some lines with a competing face. Not a real problem in this case as I can just use hidden lines for a 2d object. In my case I'm rendering BI shaded objects with multiple Freestyle wireframe overlays (for multiple colors) so I need solids. There was not enough layers in Blender to trivially make render passes via layers so I was just aiming for the easiest way to get the results. Is it impossible to render cube.003 so that it's lines would not be clipped by cube.002 without using render passes (per object visible lines instead of full render visible lines)?

Tamito Kajiyama was unassigned by Dalai Felinto

2019-12-23 16:37:22 +01:00

Jeroen Bakker commented

2020-01-27 09:16:13 +01:00

Added subscriber: @Jeroen-Bakker

Jeroen Bakker commented

2020-01-27 09:16:13 +01:00

Freestyle Line renderer is an unmaintained area in Blender. As we won't be solving this in the near future the tracker rules state that we need to register this as a known issue.

Too bad the original issue didn't had a screen shot so we could compare if the issue has improved.

Freestyle Line renderer is an unmaintained area in Blender. As we won't be solving this in the near future the tracker rules state that we need to register this as a known issue. ![#46978.png](https://archive.blender.org/developer/F8304482/T46978.png) Too bad the original issue didn't had a screen shot so we could compare if the issue has improved.

Philipp Oeser removed the

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Freestyle wireframe-only rendering is broken with Ztrans faces (lines disappear when Ztrans alpha and Ztrans spec are set to zero / lines behind transparent faces are not rendered / marked edges are not sometimes rendered when faces overlap) #46978