Cineversity

Hi

I’ve modelled a potato using a standard sphere and I’ve added some displacement and y-scale. I removed the poles at both ends with a quad layout and unwrapped the uv. It is nicely textured now and I would like the skin to peel of from the top on a helix path toward the bottom in one long peel.

Any tips are welcome!

Hi pixel phil,

The modeling should have been done with this in mind.

I would see two ways to create a peel in a helix way.

• Re-topolgize with the pen tool to create a peel in the way you need, then animate from there.

• Project a Helix [spherical] and scale up a tiny bit. Use this for a Spline Knife [R18] for all four sides [selected].  Since the Split allows only to filter by selected, not by visible.

This gives you the polygons in a peel shape. With Split and selected only as suggestion [Knife]. I tried several ways, but this seems to be the fastest.

• Another way would be to project a plane around with a Shear Deformer first to get the Top row connect on one side with the second row on the other, to have a sequence of polygons.

Either way, a Spline and/or Joint set up will then peel the polygons. To rotate the helix by 180º, I found it a good starting place as Joint position. I haven’t found a quick way to weight them automatically, though.

I explored each of these ways to a certain degree, to give you the kind of information to select one and explore it with your model, which I do not know at all.

All the best

Screenshots, just sketches, nothing final:
https://www.amazon.com/clouddrive/share/IYQQPE4apnydtOCP49uiC760zp82WQqDQ2U7p4mbheu?ref_=cd_ph_share_link_copy
https://www.amazon.com/clouddrive/share/KGCd20I3NPYtC66VQ6UdBSoI2wbNlVFsB98PEORRQG6?ref_=cd_ph_share_link_copy
https://www.amazon.com/clouddrive/share/IhWlRopFjJOAO5pNCbj44398Ebm2UbBKK4Dts56g1od?ref_=cd_ph_share_link_copy

Post edited.

thank you, polygon pen. great tool!

Hi pixel phil,

I have tried many ways, but I think a good polygon typology is a good start. The animation of such is of course no simple.

I though also to just use a long polygon stripe “Wrapped” [Helix/projected] around the potato. This needs then to overlap, and an alpha channel to define the “peel-shape” (e.g., BodyPaint 3D). This would allow to have a more realistic edge where the cut is. Baking texture, displacement, etc. might be a good technique to use here as well.

Either way, start with a simple model, to get the method you like, then go to the fine-detailed one. It is always tempting to detail too much and build up an resistance to start over with it, not my suggestion.

It is one of the more complex animations (if it should look naturalistic and not procedural), hence why I suggest to start with a simple model first.

All the best

The quick workflow.

Wrap a plane with a Bend Deformer around the object, just close not tight. Or what ever your animation needs. Just so you get a close cover.

Then make this editable, and apply a material set to spherical. Check that the Texture Sphere (Texture Mode) covers the whole object. Delete the UV tag. Then Tags>Generate UVW Coordinates.

“Displacement-Bake” this object, by pulling the main object in the Bake field - Source . (Potato) Use a high bit depth and resolution!

Delete the UV tag from the object with the deformer, and copy the UV Tag from the Baked object to the Deformed. Load the Displacement and set the same values (Height and Method—e.g., Intensity Centered)

Switch the object with the bake tag to invisible.

Render. The Deformed Object should look similar. This deformed and displaced object can now be animated without losing the surface information of the main object (Potato).

I have tried also stronger structures, since I do not know your object, I hope that works for your model as well.

I have attached an example file:
https://www.amazon.com/clouddrive/share/J1Bibl836yFNbnlamoEb9FXACJ4vS0ecXokfgL8UV01?ref_=cd_ph_share_link_copy

All the best

P.S.: If you have created a PenTool Stripe, you might like to explore this little set up.

Click on the Xpresso Tag and go to the Attribute Manager>User Data. Change the Spline interface.

This can be animated. A and B can be in-visible for editor and/or rendering.

https://www.amazon.com/clouddrive/share/RSX94Yne9UHfGmGFUL0OmH4TpOZIcJXRUqcsYVaeNUD?ref_=cd_ph_share_link_copy
…and animated
https://www.amazon.com/clouddrive/share/kbRmRA75cchL11ktqgdNIHk39A4XMU0q9v8QY4pFE2K?ref_=cd_ph_share_link_copy

Side note: If the stripe has more points than in this example, where it has two, I would set up a different way, so the edge (perpedicular to the stripe) will get the information at once.

How to get a Helix along an object?

Have a look at this screen-shot
https://www.amazon.com/clouddrive/share/6iehLcQCOp39b7Qu9YAcnB6hfOX5XcXXnlHhu1EZPIV?ref_=cd_ph_share_link_copy

• I have select all the vertical edges (Ring Selections+Shift Click along one edge-sequence)
• Mesh>Commands…>Edge To Spline (Check the [point] directions!)
• Then created Nulls,( Segment count times vertical amount wanted)
• Xpresso Set up
• Place the all Nulls in a Tracer, copied it, and deleted the first Nulls (amount subtracted equal to segments) then in the second the last Nulls (amount subtracted equal to segments). So the two can create a Loft.

(One could create more Tracer/Null combinations to create more refined Surfaces with the Loft. This would be done by changing the math for the off-set, e.g., off-setting the off-set ;o)

Just an idea and here is the XPresso example for it:
https://www.amazon.com/clouddrive/share/8C16P8QyDHUNN1hBNOLvT68D7K4kodndwnEjo3pZe61?ref_=cd_ph_share_link_copy

This stripe can be used now with the ideas above to bake the displacement, for example.

The most exciting options is given by placing a Range Mapper between the Divide node and the Off-set input, and then play with the Spline-Curve-Interface!
Check out this one minute video clip:
https://www.amazon.com/clouddrive/share/7DHGn3pwvkkXSUqckd5LAwWVoiuCinxHvew2B3XYrMv?ref_=cd_ph_share_link_copy
The updated file is here:
https://www.amazon.com/clouddrive/share/dvIh4iijGKnbyPcDrje3SX4G8NIURyJu9wNBE4SASJ3?ref_=cd_ph_share_link_copy

To deform the example more to a potato, one needs to deform the sphere and the spline in the same way, use for the spline a “Current State To Object”, and drag that new “version” on to the Object-Node to have that update spline working.
Example is here:
https://www.amazon.com/clouddrive/share/SWkGa0H0lpQcpaELIDN5mXnNRuLcZ1orhfthQKWBgvx?ref_=cd_ph_share_link_copy

Enjoy.