Animate unrolling sail

In my model I have a rolled up triangular sail around a rope:


The sail is currently modelled as a mesh. However I want to have an animation unrolling the sail and I am unsure how to get about.
I could imagine to have one part where the triangular sail moves in (left to right in the image) but only the part below the “rope” would be visible combined with somehow reducing the amount of the rolled up sail.
Especially this second part I am clueless. In addition the sail has a pattern, that would also move while the sail is unrolled.

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Hi @hotzst,

A lot will depend on what you’re intention is in terms of visible details, the more convincing the animation has to appear the more elaborate the setup will need to be, but in general what you’re after is quite straightforward.

The sail will need to be modelled unwound, with a high poly count to allow it to be wrapped smoothly. It will also need to be properly UVmapped to maintain texture integrity. The sail is then animated ( with simple keying ) to travel along a path that is spiral at one end and then straightens out. The sail and the Spiral both need to be parented to a third object ( like the mast ) if you want to animated the whole ship moving too. Any addition ‘tackle’ will need hand animating to match the unfurl, this is where it would get complicated :wink:.

This is what a basic setup looks like. And I’ve also attached the Blend file for you to explore. There are other ways of acheiving the same thing with path curve deformations etc, but those are too much to cover in this post.

sail_unwind.blend (1.1 MB)

The texture on this sail is procedural to demonstrate that texturing works. You can obviously use a regular image map.

Cheers,
Dj.

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Thanks, this looks definitely more useful than what I imagined. Any tips on how you set up the curve path along which the sail is animated? Or is this just tedious work?

Hi,

I used the spiral path generator that is in 2.79:

image

then simply extruded ( the ‘e’ key in vertex selection ) on the outside end one to straighten the path out. It’s a bit of trial and error because the length of the spiral part of the path has to be long enough to allow the sail to fully wrap up, if it isn’t the sail will continue past the end of the spiral ( on the inside ) and intersect itself as it emerges along a tangent of it’s last vertex. Hand constructing such a spiral is not excessively tedious, and will have the aesthetic advantage of not being ‘perfect’.

Dj.

Created a tutorial video of the process: https://youtu.be/jnB7sjYcQI0

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