3D curve - bevel profile not deformed at corners to cope with 'shrinking' effect (works OK with 2D curves). #47230

New Issue

daniel · 2016-01-24T21:00:23+01:00

daniel commented

2016-01-24 21:00:23 +01:00

System Information
windows xp, windows 7

Blender Version
Broken: (example: 2.76b f337ea)
Worked: (2.63a r46461)

Short description of error
when you bevel curve in 3D type it does not carry the same profile along the lenght as it should.
in 2.63a version it works better than in the newer ones but is also far from correct and acceptable working. when the curve turn in angle different than 90 degree the starting profile changes but should stay the same.nothing helps.none of changing settings. curve points etc
Exact steps for others to reproduce the error
open the attached file in 2.63a version and in 2.76b and look at the curve at the right which is 3D type. they look different, in 2.63a correct.
curve_bevel.blend

**System Information** windows xp, windows 7 **Blender Version** Broken: (example: 2.76b f337ea) Worked: (2.63a r46461) **Short description of error** when you bevel curve in 3D type it does not carry the same profile along the lenght as it should. in 2.63a version it works better than in the newer ones but is also far from correct and acceptable working. when the curve turn in angle different than 90 degree the starting profile changes but should stay the same.nothing helps.none of changing settings. curve points etc **Exact steps for others to reproduce the error** open the attached file in 2.63a version and in 2.76b and look at the curve at the right which is 3D type. they look different, in 2.63a correct. [curve_bevel.blend](https://archive.blender.org/developer/F277089/curve_bevel.blend)

daniel commented

2016-01-24 21:00:23 +01:00

Changed status to: 'Open'

daniel commented

2016-01-24 21:00:23 +01:00

Added subscriber: @midan-3

Ignatz commented

2016-01-25 11:30:23 +01:00

Added subscriber: @ignatz

Ignatz commented

2016-01-25 11:30:23 +01:00

I downloaded the above file and played around with it.

I would have to agree that there is something seriously wrong with the projection of a curve along a curve.

It seems to work well enough in the 2D mode, but once in 3D mode the profile form is corrupted where the curve takes an angle or bend.

It is also worth noting that while testing this out I tried subdividing the curve while in edit mode to add extra points. I then moved these points off of the original plane of the curve (in Y) while in the shape 3D setting. Again, the profile was compromised at every bend or curve. The odd behaviour, however, was if one then toggled into the shape 2D setting. At that moment, all of my editing of the positions of the points (in Y) of the curve were lost. All points of the curve were simply mapped back into a single plane, the Y offset information and/or rotation of the angles of the arms of the points being trashed. Pressing the shape 3D button at the point did not restore the missing point information (although a simple UNDO would do so. This is pretty questionable behaviour.

It is perhaps best if some talented programmer put eyes on this function. It would be a real plus for the model-building, especially for those who want to do mechanical or architectural work.

I downloaded the above file and played around with it. I would have to agree that there is something seriously wrong with the projection of a curve along a curve. It seems to work well enough in the 2D mode, but once in 3D mode the profile form is corrupted where the curve takes an angle or bend. It is also worth noting that while testing this out I tried subdividing the curve while in edit mode to add extra points. I then moved these points off of the original plane of the curve (in Y) while in the **shape 3D** setting. Again, the profile was compromised at every bend or curve. The odd behaviour, however, was if one then toggled into the **shape 2D** setting. At that moment, all of my editing of the positions of the points (in Y) of the curve were lost. All points of the curve were simply mapped back into a single plane, the Y offset information and/or rotation of the angles of the arms of the points being trashed. Pressing the **shape 3D** button at the point did not restore the missing point information (although a simple **UNDO** would do so. This is pretty questionable behaviour. It is perhaps best if some talented programmer put eyes on this function. It would be a real plus for the model-building, especially for those who want to do mechanical or architectural work.

Bastien Montagne commented

2016-01-29 12:41:02 +01:00

Added subscribers: @Sergey, @mont29

Bastien Montagne commented

2016-01-29 12:41:02 +01:00

Can confirm the issue, kinda unsure whether this is real bug or known limitation though, @Sergey should know?

@ignatz I wonder why you’d expect from a 2D curve to keep 3D coordinates…

Can confirm the issue, kinda unsure whether this is real bug or known limitation though, @Sergey should know? @ignatz I wonder why you’d expect from a 2D curve to keep 3D coordinates…

Bastien Montagne changed title from ~~curve 3D type bevel issue~~ to 3D curve - bevel profile not deformed at corners to cope with 'shrinking' effect (works OK with 2D curves).

2016-01-29 12:43:18 +01:00

Ignatz commented

2016-01-29 14:25:50 +01:00

I do not feel that the new title of this bug "bevel profile not deformed at corners to cope with 'shrinking' effect", actually describes the problem correctly.

The bevel profile should not 'shrink' at the corners. The truth of the matter is that the original profile should be projected onto the plane that exactly divides the two legs of the curve in 3D space.

I have attempted to demonstrate this with the attached blend file and associated images.

In the first image (pipes_01.jpg) at 'A' you have the behaviour of in blender of using a curve circle as a bevel object along a curve. It easy to see that where the curve takes a turn the profile is not correct. The profile of the circle along the curve is compromised and most definitely shrunk. But this should not be.

At 'B' in the same image I have attempted to show the series of straight tube sections that one would expect to recieve form the 3D bevel object function.

At 'C'and'D' I have attempted to actually distill the desired corner profiles out my assemby of tubes. This is something which I could only achieve in a very crude way. Blender does not give me the tools with which to achieve this desired result.

The second image (pipes_02.jpg) shows the desired corner profiles (1, 2 & 3) more clearly.

mock-up 3D projection.blend

I do not feel that the new title of this bug "bevel profile not deformed at corners to cope with 'shrinking' effect", actually describes the problem correctly. The bevel profile should not 'shrink' at the corners. The truth of the matter is that the original profile should be projected onto the plane that exactly divides the two legs of the curve in 3D space. I have attempted to demonstrate this with the attached blend file and associated images. In the first image (**pipes_01.jpg**) at **'A'** you have the behaviour of in blender of using a curve circle as a bevel object along a curve. It easy to see that where the curve takes a turn the profile is not correct. The profile of the circle along the curve is compromised and most definitely shrunk. But this should not be. At **'B'** in the same image I have attempted to show the series of straight tube sections that one would expect to recieve form the 3D bevel object function. At **'C'**and**'D'** I have attempted to actually distill the desired corner profiles out my assemby of tubes. This is something which I could only achieve in a very crude way. Blender does not give me the tools with which to achieve this desired result. The second image (**pipes_02.jpg**) shows the desired corner profiles (1, 2 & 3) more clearly. [mock-up 3D projection.blend](https://archive.blender.org/developer/F278700/mock-up_3D_projection.blend) ![pipes_01.jpg](https://archive.blender.org/developer/F278701/pipes_01.jpg) ![pipes_02.jpg](https://archive.blender.org/developer/F278703/pipes_02.jpg)

Ignatz commented

2016-01-29 19:06:14 +01:00

Have to point this out, too.

I know it is not usually done to confuse an issue by mixing more than one buggy function into a single report.

However, since I was curious about the performance of 3D curve as a bevel object on a curve I also decided to put eyes on the Follow Curve modifier.

I find that the Follow Curve modifier evidently also uses the same incorrect code routine. It might be worth it to examine that at the same time.

If you examine the attached file and images (especially 'follow_curve modifier 02.jpg') you will see that the mesh tube which is folloing the curve is becoming stretched and squeezed without reason. The Z-axis of the mesh profile is continuously altering its rotation with respect to the axis of the curve it is following. This is not good.

This is such an important model-building funtion that it really should be made to work correctly.

follow curve modifier problem.blend

Have to point this out, too. I know it is not usually done to confuse an issue by mixing more than one buggy function into a single report. However, since I was curious about the performance of **3D curve as a bevel object** on a curve I also decided to put eyes on the **Follow Curve modifier**. I find that the Follow Curve modifier evidently also uses the same incorrect code routine. It might be worth it to examine that at the same time. If you examine the attached file and images (especially 'follow_curve modifier 02.jpg') you will see that the mesh tube which is folloing the curve is becoming stretched and squeezed without reason. The Z-axis of the mesh profile is continuously altering its rotation with respect to the axis of the curve it is following. This is not good. This is such an important model-building funtion that it really should be made to work correctly. [follow curve modifier problem.blend](https://archive.blender.org/developer/F278865/follow_curve_modifier_problem.blend) ![follow_curve modifier 01.jpg](https://archive.blender.org/developer/F278866/follow_curve_modifier_01.jpg) ![follow_curve modifier 02.jpg](https://archive.blender.org/developer/F278868/follow_curve_modifier_02.jpg)

daniel commented

2016-01-30 21:43:24 +01:00

I would like to spot that this is very old issue and very important and basic in modelling(but unuseful in this form right now). Please devs to make the thing works as expected

Ignatz commented

2016-01-30 23:31:01 +01:00

I politely suggest viewing the linked video for examples of how this very necessary feature is employed within the Sketchup program.

https://www.youtube.com/watch?v=oX6bn0Q0pIM

Obviously, the function is different within Blender, but the modeling application of the function is what is important.

You will notice all sorts of ways that the curve following along a curve is used to create architectural elements.

We cannot effectively do the same sorts of things given the limitations of the current code.

I politely suggest viewing the linked video for examples of how this very necessary feature is employed within the Sketchup program. https://www.youtube.com/watch?v=oX6bn0Q0pIM Obviously, the function is different within Blender, but the modeling application of the function is what is important. You will notice all sorts of ways that the curve following along a curve is used to create architectural elements. We cannot effectively do the same sorts of things given the limitations of the current code.

Campbell Barton commented

2016-02-01 13:40:36 +01:00

Added subscriber: @ideasman42

Campbell Barton commented

2016-02-01 13:40:36 +01:00

Think this is intentional, but checking on commits between 2.68a-2.69 (bisected down to 4941cafa09)

Think this is intentional, but checking on commits between 2.68a-2.69 (bisected down to 4941cafa09)

Sergey Sharybin was assigned by Campbell Barton

2016-02-02 07:32:38 +01:00

Sergey Sharybin commented

2016-04-26 15:09:47 +02:00

Changed status from 'Open' to: 'Archived'

Sergey Sharybin closed this issue

2016-04-26 15:09:47 +02:00

Sergey Sharybin commented

2016-04-26 15:09:47 +02:00

I can see why old behavior would be preferrable in certain cases, but as #36007 shows it's not always the case.

Surely some option could be added to support both cases, but then it all becomes to be quite tricky to work on splines: global option might be not granular enough, default value of that option is also another story. While curves in blender are really requiring some major refresh will consider this a TODO.

So thanks for the report, but closing it now.

I can see why old behavior would be preferrable in certain cases, but as #36007 shows it's not always the case. Surely some option could be added to support both cases, but then it all becomes to be quite tricky to work on splines: global option might be not granular enough, default value of that option is also another story. While curves in blender are really requiring some major refresh will consider this a TODO. So thanks for the report, but closing it now.

Marlon commented

2020-10-27 14:46:06 +01:00

Added subscriber: @MarlonBoettger

Marlon commented

2020-10-27 14:46:06 +01:00

It would be great if this could be fixed, it's annoying how curves compress the bevel at a sharp bend.

Baxter commented

2020-11-05 15:58:39 +01:00

Added subscriber: @8axter

Baxter commented

2020-11-05 15:58:39 +01:00

I would also love to see this finally working. Extruding along a curve is one of the most basic features. It works flawlessly in Sketchup, MAx, Maya.... Why wouldn't we deserve it in Blender? I tried all trick I found online and none of them makes my 3D curves to have the same thickness. They always get tapered + twisted i sharp corners.

Pablo Caracena commented

2020-11-19 02:41:21 +01:00

Added subscriber: @Pablo_Caracena

Pablo Caracena commented

2020-11-19 02:41:21 +01:00

Hi, thanks for developing Blender!

I just made this account to say that this seems to me like a necessary feature for any 3D software.

While you can fix it manually, it's very tedious and is something you can do easily in most other modeling softwares.

I think devs should give some priority to this feature, it's been almost 5 years.

Hi, thanks for developing Blender! I just made this account to say that this seems to me like a necessary feature for any 3D software. While you can fix it manually, it's very tedious and is something you can do easily in most other modeling softwares. I think devs should give some priority to this feature, it's been almost 5 years.

Nika-Kasradze commented

2023-06-25 21:33:35 +02:00

Please keep this issue open

EDIT:
Currently there is a related PR open regarding this issue: #108700
This fixes the issue ONLY IN GEOMETRY NODES as stated HERE by bruno.chartier
you can download the Blender patch version with this feature HERE

Please keep this issue open EDIT: Currently there is a related PR open regarding this issue: #108700 This fixes the issue ONLY IN GEOMETRY NODES as stated [HERE](https://blender.community/c/rightclickselect/BPcbbc/) by bruno.chartier you can download the Blender patch version with this feature [HERE](https://builder.blender.org/download/patch/PR108700/)

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3D curve - bevel profile not deformed at corners to cope with 'shrinking' effect (works OK with 2D curves). #47230