different render result using screw modifier #51451

New Issue

Nicola · 2017-05-10T15:35:59+02:00

Nicola commented

2017-05-10 15:35:59 +02:00

System Information
windows 10, nvidia 970gtx (381.89)

Blender Version
Broken: 2.78.5 717d85f

Short description of error
different render result using screw modifier

Exact steps for others to reproduce the error
with the attached file strange_error.blend

rendering the object created with screw modifier, get the result on first png
rendering the object converted in mesh, get the result on second png

{F594320}

**System Information** windows 10, nvidia 970gtx (381.89) **Blender Version** Broken: 2.78.5 717d85f **Short description of error** different render result using screw modifier **Exact steps for others to reproduce the error** with the attached file [strange_error.blend](https://archive.blender.org/developer/F594319/strange_error.blend) - rendering the object created with screw modifier, get the result on first png - rendering the object converted in mesh, get the result on second png {[F594320](https://archive.blender.org/developer/F594320/original_screw.png)}![edited_screw.png](https://archive.blender.org/developer/F594327/edited_screw.png)

Nicola commented

2017-05-10 15:35:59 +02:00

Changed status to: 'Open'

Nicola commented

2017-05-10 15:35:59 +02:00

Added subscriber: @NicolaFrascati

Joel Godin commented

2017-05-10 18:04:03 +02:00

Added subscriber: @FloridaJo

Joel Godin commented

2017-05-10 18:04:03 +02:00

I'm not seeing the issue. Can you list the steps taken from the start?
I did this:

add curve, move from origin, add screw modifier.
render
Convert to mesh from curve,
render

I don't see any difference.

I'm not seeing the issue. Can you list the steps taken from the start? I did this: 1) add curve, move from origin, add screw modifier. 2) render 3) Convert to mesh from curve, 4) render I don't see any difference.

Nicola commented

2017-05-10 18:34:52 +02:00

In #51451#432952, @FloridaJo wrote:
I'm not seeing the issue. Can you list the steps taken from the start?
I did this:

add curve, move from origin, add screw modifier.

render

Convert to mesh from curve,

render

I don't see any difference.

using the .blend file attached:

select render in new window from render tab
hit render as it is and saving in slot 1 (the object is a curve+screw mod+subsurf+mirror)
change to slot 2
convert the object to mesh
hit render again and see the difference

> In #51451#432952, @FloridaJo wrote: > I'm not seeing the issue. Can you list the steps taken from the start? > I did this: > 1) add curve, move from origin, add screw modifier. > 2) render > 3) Convert to mesh from curve, > 4) render > > I don't see any difference. using the .blend file attached: - select render in new window from render tab - hit render as it is and saving in slot 1 (the object is a curve+screw mod+subsurf+mirror) - change to slot 2 - convert the object to mesh - hit render again and see the difference

Joel Godin commented

2017-05-10 19:37:53 +02:00

Couple of things I noticed. (may or may not mean anything)

If I create a similar object from curve from scratch, it does not do as your file does.
On your file if I apply 'location' it changes the object shape.
If I go to the curve object data panel and change from 3D to 2D and back to 3D the viewport render matches the final render.

I think there may be a clue in 3) but I'll defer to someone more knowledgeable on this.

Couple of things I noticed. (may or may not mean anything) 1) If I create a similar object from curve from scratch, it does not do as your file does. 2) On your file if I apply 'location' it changes the object shape. 3) If I go to the curve object data panel and change from 3D to 2D and back to 3D the viewport render matches the final render. I think there may be a clue in 3) but I'll defer to someone more knowledgeable on this.

Nicola commented

2017-05-11 08:18:18 +02:00

In #51451#432978, @FloridaJo wrote:
Couple of things I noticed. (may or may not mean anything)

If I create a similar object from curve from scratch, it does not do as your file does.

the same for me

On your file if I apply 'location' it changes the object shape.

the same for me also here on my file, it seems it change the origin to center of world space and I don't know why

If I go to the curve object data panel and change from 3D to 2D and back to 3D the viewport render matches the final render.

I think there may be a clue in 3) but I'll defer to someone more knowledgeable on this.

do you mean on my file or on a new? Because on my file it completely change the curve shape and I can't go back to original if I do as you wrote, I've to undo the operation.

I think there's something wrong with the management of curve origin position, and maybe with the curve+modifiers,
but are only my suppositions

> In #51451#432978, @FloridaJo wrote: > Couple of things I noticed. (may or may not mean anything) > > 1) If I create a similar object from curve from scratch, it does not do as your file does. - the same for me > 2) On your file if I apply 'location' it changes the object shape. - the same for me also here on my file, it seems it change the origin to center of world space and I don't know why > 3) If I go to the curve object data panel and change from 3D to 2D and back to 3D the viewport render matches the final render. > > I think there may be a clue in 3) but I'll defer to someone more knowledgeable on this. - do you mean on my file or on a new? Because on my file it completely change the curve shape and I can't go back to original if I do as you wrote, I've to undo the operation. I think there's something wrong with the management of curve origin position, and maybe with the curve+modifiers, but are only my suppositions

Joel Godin commented

2017-05-11 14:48:17 +02:00

On 3) I mean I hit the 2D tab and it changes to the rendered shape (the smaller circle) and when I go back to the 3D tab, it does not change back, it stays the smaller (more correct) shape.

ronan ducluzeau commented

2017-05-11 16:40:37 +02:00

Added subscriber: @zeauro

ronan ducluzeau commented

2017-05-11 16:40:38 +02:00

There is no bug, here.

You just did not set same number of steps for screw modifier for Viewport and for Render.
There are only 6 steps for Render against 72 for Viewport.

So, subdivision surface modifier will affect the resulting geometry differently, producing a more important shrinking on an hexagonal shape than on a circular basis made of 72 sides.
You just have to precise same number of render steps to obtain same result.

There is no bug, here. You just did not set same number of steps for screw modifier for Viewport and for Render. There are only 6 steps for Render against 72 for Viewport. So, subdivision surface modifier will affect the resulting geometry differently, producing a more important shrinking on an hexagonal shape than on a circular basis made of 72 sides. You just have to precise same number of render steps to obtain same result.

Joel Godin commented

2017-05-11 16:52:30 +02:00

Changed status from 'Open' to: 'Archived'

Joel Godin closed this issue

2017-05-11 16:52:30 +02:00

Joel Godin self-assigned this 2017-05-11 16:52:30 +02:00

Joel Godin commented

2017-05-11 16:52:30 +02:00

Added subscriber: @RonanZeegers

Joel Godin commented

2017-05-11 16:52:30 +02:00

@RonanZeegers Good catch.
Closed.

@RonanZeegers Good catch. Closed.

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different render result using screw modifier #51451