Bridge tool fails in a few cases #48365

New Issue

Leon Cheung · 2016-05-07T03:38:58+02:00

Leon Cheung commented

2016-05-07 03:38:58 +02:00

System Information
Win8.1 64bit | GTX680

Blender Version
Broken: v2.77 3045011
Worked: N/A

Short description of error
After testing the fix for #48356, I found there are a few other cases failed. Not sure if it deserves further attention.

Exact steps for others to reproduce the error

bridge_example.blend

**System Information** Win8.1 64bit | GTX680 **Blender Version** Broken: v2.77 3045011 Worked: N/A **Short description of error** After testing the fix for #48356, I found there are a few other cases failed. Not sure if it deserves further attention. ![bridge_case.png](https://archive.blender.org/developer/F309649/bridge_case.png) **Exact steps for others to reproduce the error** [bridge_example.blend](https://archive.blender.org/developer/F309653/bridge_example.blend)

Leon Cheung commented

2016-05-07 03:38:59 +02:00

Changed status to: 'Open'

Leon Cheung commented

2016-05-07 03:38:59 +02:00

Added subscriber: @ZhangYu

Campbell Barton commented

2016-05-08 18:46:44 +02:00

Added subscriber: @ideasman42

Campbell Barton commented

2016-05-08 18:46:45 +02:00

Currently the method used to calculate bridge direction relies on the face regions not being planar to each-other.

Probably the best solution in this case is to always use the use the face winding when its defined for both loops (instead of relative orientation).

Currently the method used to calculate bridge direction relies on the face regions _not_ being planar to each-other. Probably the best solution in this case is to always use the use the face winding when its defined for both loops (instead of relative orientation).

Campbell Barton commented

2016-05-09 08:23:58 +02:00

Note, e0e7d94f79 fixes the cases where boundary edges were being removed.

Note, e0e7d94f79 fixes the cases where boundary edges were being removed.

Campbell Barton was assigned by Sergey Sharybin

2016-05-17 17:52:50 +02:00

Sergey Sharybin commented

2016-05-17 17:52:50 +02:00

Added subscriber: @Sergey

Campbell Barton commented

2016-08-03 06:32:33 +02:00

Changed status from 'Open' to: 'Archived'

Campbell Barton closed this issue

2016-08-03 06:32:33 +02:00

Campbell Barton commented

2016-08-03 06:32:33 +02:00

Summary if the problem, bridge is split into 2 steps.

The bridge is calculated and connected.
The edges from the bridge are then subdivided and made into a curve.

In the case where both loops are on a flat plane, its possible that the curve direction selected is different to the winding direction used when connecting the bridge.

For this to work as expected, either:

the bridge normals used for calculating the initial bridge would need to be passed to the subdivision function.
the winding of faces would need to be evaluated to calculate the normals for the curve.

Note that its possible to use an entirely different method of calculating handles, however this would need to be applied only for flat cases, which are tricky to detect since there would be some threshold which loops would not be considered flat, and this may give unpredictable behavior.

This whole situation is kind of a corner case, when bridging between 2 loops which are exactly aligned next to eachother, then applying curvature -it's not very obvious what the outcome should be regarding curvature. Using face normals one can be selected, so its possible of course. But still something the bridge tool isn't really setup to solve well.

Closing this report. If someone likes to solve its fine, but this is really at the limit of whats supported by this tool.

Summary if the problem, bridge is split into 2 steps. - The bridge is calculated and connected. - The edges from the bridge are then subdivided and made into a curve. In the case where both loops are on a flat plane, its possible that the curve direction selected is different to the winding direction used when connecting the bridge. For this to work as expected, either: - the bridge normals used for calculating the initial bridge would need to be passed to the subdivision function. - the winding of faces would need to be evaluated to calculate the normals for the curve. Note that its possible to use an entirely different method of calculating handles, however this would need to be applied only for `flat` cases, which are tricky to detect since there would be some threshold which loops would not be considered flat, and this may give unpredictable behavior. This whole situation is kind of a corner case, when bridging between 2 loops which are exactly aligned next to eachother, then applying curvature -it's not very obvious what the outcome should be regarding curvature. Using face normals one can be selected, so its possible of course. But still something the bridge tool isn't really setup to solve well. Closing this report. If someone likes to solve its fine, but this is really at the limit of whats supported by this tool.

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Bridge tool fails in a few cases #48365