Blender 2.48(a) Shrinkwrap modifier offset bug?

General Forums Blender and CG Discussions
#1

I’ve been experimenting with the shrinkwrap modifier in 2.48a. And have a question about the offset value (allows value of zero and greater than zero).

My setup:

  • I added a sphere.
  • I added an open ended cylinder.
  • I then used the multi-cut knife tool (20 cuts) to add some segmentation along the length.
  • The sphere sits in the center of the cylinder and has a larger radius than the cylinder.
  • The sphere diameter is also about two-thirds the height of the cylinder.
  • Added the shrinkwrap modifier to the cylinder.
  • Target is the sphere
  • Type is projection
  • The positive toggle is selected (all other projection type toggles are un-selected)
  • SS Levels is 0

When I set the offset value to non-zero the surface of the cylinder moves inside that of the sphere. I would have expected the surface of the cylinder to move outward away from the surface of the sphere.

Can anyone else replicate this? Is this as it should be?

I tried flipping the normals to see if this would affect how the offset is applied but no change in the behavior.

** EDIT ** Here is the blend

Got some time to upload the blend file. Offset is 0.03 but offsets into the sphere instead of away from it.

Shringwrap test Blend

#2

is it a normals issue?

#3

That was my first thought. And could very well be I suppose but flipping the normals of either mesh don’t seem to change anything about the shrinkwrap projection. Just want to see if anyone can duplicate this with 2.48 or 2.48a before making a bug report.

#4

Got some time to upload the blend file. Offset is 0.03 but offsets into the sphere instead of away from it.

Shringwrap test Blend

#5

Hi FMM :slight_smile:
For me it’s OK. When object is smaller than target object , like in your .blend file , it needs to be stretching/growing (not shrinking) to target size because is smaller , and is touching target from inside.
Here is image with object which partially lays inside and partially outside of target-sphere. And you can see the object is partially shrinking and partially stretching to sphere faces.
That’s my opinion.
Cheers.

http://img375.imageshack.us/img375/650/shrinkwrapdu9.jpg

And .blend file : shrinkwrap2.zip.

#6

My apologies, just noticed your reply. Thank you for the image and the blend.

It’s not something I expected to see, but I see your point and it is not something I had considered. So not a bug I guess. Perhaps it’s an option that could be added though. i.e. “Force outside” or something. Anyway, was testing it out and it seemed odd.