Bevel should not create vertex meshes when only two edges at a vertex are beveled. #44742

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Howard Trickey · 2015-05-17T18:19:19+02:00

Howard Trickey commented

2015-05-17 18:19:19 +02:00

A user request is to be more like a competing program on bevels at vertices where exactly two edges (among many) are beveled.
Here is a picture showing what is desired: . The example blend file is here: beveltest-01.blend

The current Blender bevel code attempts to keep non-beveled edges going having the same direction as they had before the bevel, in the belief that those edges may be important to the silhouette of the model. Also, in the case where there is only one non-beveled edge on a given side of the bevel, then artists like an effect that looks like loop slide along that edge when you bevel. Following the first principle, if there are more than one non-beveled edge on a given side of a bevel, the current code makes a polygon at the bevel juncture. In the attached picture, the artist would prefer not doing that, even if it means changing the angles of some of the non-beveled edges.

I have a patch that implements the desired behavior but would like the patch reviewed, so am putting some context for the reason for this patch into this task. I'll update this task when I've uploaded the patch.

A user request is to be more like a competing program on bevels at vertices where exactly two edges (among many) are beveled. Here is a picture showing what is desired: ![blenderbevelVSmaya-01.jpg](https://archive.blender.org/developer/F175881/blenderbevelVSmaya-01.jpg). The example blend file is here: [beveltest-01.blend](https://archive.blender.org/developer/F175883/beveltest-01.blend) The current Blender bevel code attempts to keep non-beveled edges going having the same direction as they had before the bevel, in the belief that those edges may be important to the silhouette of the model. Also, in the case where there is only one non-beveled edge on a given side of the bevel, then artists like an effect that looks like loop slide along that edge when you bevel. Following the first principle, if there are more than one non-beveled edge on a given side of a bevel, the current code makes a polygon at the bevel juncture. In the attached picture, the artist would prefer not doing that, even if it means changing the angles of some of the non-beveled edges. I have a patch that implements the desired behavior but would like the patch reviewed, so am putting some context for the reason for this patch into this task. I'll update this task when I've uploaded the patch.

Howard Trickey commented

2015-05-17 18:19:19 +02:00

Changed status to: 'Open'

Howard Trickey self-assigned this 2015-05-17 18:19:19 +02:00

Howard Trickey commented

2015-05-17 18:19:19 +02:00

Added subscribers: @ideasman42, @Sergey

Howard Trickey commented

2015-05-17 18:30:46 +02:00

Here is a patch that adds the new functionality under control of a parameters variable called new_vmesh. I enabled that parameter by default but you can disable it (by code editing) if you want to see the old behavior.

newvmeshpatch.diff

(I made this patch on windows so apologize if CRLFs make it annoying to use. Not sure if that will be the case.)

If we like the effect of this patch, there's the question of which of these three things to do:

make it a user-visible option (but there isn't a good name for this: something like "Avoid vertex polygons" is the best I can come up with)
make it an option in the internal interface and code, and use do_versions to select between the new and old code depending on the blender version, so as not to break old models that have bevel modifiers and maybe liked the old effect. (If I do this, I might make the internal variable called something like "bevel_algorithm_version" so that future changes to the algorithm could use the same field for do_versions).
just let old versions of bevel modifiers get the new behavior and hope no-one minds too much

Opinions on which of these three options to use?

By the way, there's another difference between what Blender does and what the competing software does at vertices where just one edge is beveled and there are multiple segments and there are more than 1 unbeveled edge into the vertex: they just pick one of those edges to slide along and then make a polygon to deal with the remainder. I haven't decided whether I want to do that too (the artist didn't complain about that behavior) but I suppose if I were going to do that it could be done all at once, rather than in two steps. I think I'd rather do it in two steps.

Here is a patch that adds the new functionality under control of a parameters variable called new_vmesh. I enabled that parameter by default but you can disable it (by code editing) if you want to see the old behavior. [newvmeshpatch.diff](https://archive.blender.org/developer/F175885/newvmeshpatch.diff) (I made this patch on windows so apologize if CRLFs make it annoying to use. Not sure if that will be the case.) If we like the effect of this patch, there's the question of which of these three things to do: 1) make it a user-visible option (but there isn't a good name for this: something like "Avoid vertex polygons" is the best I can come up with) 2) make it an option in the internal interface and code, and use do_versions to select between the new and old code depending on the blender version, so as not to break old models that have bevel modifiers and maybe liked the old effect. (If I do this, I might make the internal variable called something like "bevel_algorithm_version" so that future changes to the algorithm could use the same field for do_versions). 3) just let old versions of bevel modifiers get the new behavior and hope no-one minds too much Opinions on which of these three options to use? By the way, there's another difference between what Blender does and what the competing software does at vertices where just one edge is beveled and there are multiple segments and there are more than 1 unbeveled edge into the vertex: they just pick one of those edges to slide along and then make a polygon to deal with the remainder. I haven't decided whether I want to do that too (the artist didn't complain about that behavior) but I suppose if I were going to do that it could be done all at once, rather than in two steps. I think I'd rather do it in two steps.

blender-admin commented

2015-06-02 15:25:05 +02:00

This issue was referenced by fd1ea5e3db

This issue was referenced by fd1ea5e3db5a66848dc532423340dce2d08ab599

Howard Trickey commented

2015-06-02 16:20:07 +02:00

Changed status from 'Open' to: 'Resolved'

Howard Trickey closed this issue

2015-06-02 16:20:07 +02:00

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Bevel should not create vertex meshes when only two edges at a vertex are beveled. #44742