Bending stuff
TangoAlpha
Posts: 4,584
Is there an easy way of bending something, such that it conforms to the shape of another object in a scene (or just sags)?
I have three specific scenarios in mind:
1. A rope that passes over a pulley, fixed at one end and a hook attached to the other.
2. A rope that passes from one post to another, and sags in between (like a red carpet barrier)
3. Cables that wrap around the sides of a building, but also wrap around obstacles such as window sills, aircon units or anything else that might get in the way.
Assuming for simplicity that my rope/cable is a simple cylinder with lots of segments (i.e. not a billion-poly splined spiral), my initial thought is to attach bones to the cylinder and pose it. Can I then take the bones off, when posing is complete, assuming I don't want it to be user posable?
For scenario 2, another thought that occurred is to use soft body physics - not quite sure how or if that would work, but I'm hoping I could effectively drape the rope in a fashion similar to dynamic cloth in Poser (i.e. position, add gravity and run a sim on it). Possibly that would also allow by dangling hook rope to sway in the wind, or rich to and fro, like a wrecking ball?
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Comments
In your first option using bones, you might be able to avoid having to rig the thing, by instead using a simple soft selection, editing the rope/cable in the assembly room after spreading it between the two areas where it's fixed. And then, if it's to become an animation, you could apply the soft-body physics to the end of the rope with the hook, and soft-body attach the top end to the pulley.
Just some thoughts. But I'm sure that others here have some tidier answers ;)
As you point out, you have a number of good options. One is to use the polyline tool and use the sweep function in the vertex modeler to extend the rope along any shaped path that you would want. Effective use of that depends on your skill with placing the polyline points where you want them. Practice makes perfect, there. The thread on temple vines has a discussion, especially 3DAGE examples here.
http://www.daz3d.com/forums/discussion/38770/P75
As you point out, you could just insert any cylinder type shape and then use the bone tools to rig a bendable rope. Note, the spline modeler might also be a good choice for something along those lines. EvilProducer mentions the spline method in a thread I will link to in connection to modifiers.
Furthermore, the "modifier" function can even be used to transform a primitive in this way. I used modifiers for my rope here (and EP brings up the spline modeler later in the same thread).
http://www.daz3d.com/forums/discussion/36508/P15
There is no right way to do it, except that you need to get the results that you want. Polyline? yes if you want. Bones and rigging? yes, if you want? Spline modeler? Yes, if you want. Primitives and modifiers? Even that would work, but frankly I only did that because the challenge was to use modifiers.
The thing about a rig for the ropes is that if you were to detach it, the model will revert back to it's original shape. You could leave the rig in place as I don't think that should be big on memory. Plus, if you later decide to animate the scene you'll have that option. If you really want to remove the rig and retain the pose, you could export as a .obj file and make sure that the export morphs and/or poses option is enabled.
It is true that I don't think the Spline modeler gets the love it deserves, but if you have specific points the ropes and cables must go over, then the rigged cable or the polyline method are the way to go. The reason I say this is because the Spline Modeler doesn't have a model in Assembly room option like the VM does.
I almost forgot! If you're doing a rigged rope, there will need to be enough cross sections to allow a good bend. This example of Christmas lights I made as a holiday gift is about as low as I could go without sharp bends at the joints. You're a better modeler than I am, so you may see some ways to do it better.
http://www.sharecg.com/v/73481/view/5/3D-Model/Carrara-rigged-Holiday-Light-String
I spent a day trying to get the magazines to sag around over each other in my banner using the bend/twist modifier. Towards the end I gave up and bought SHAPER at inagoni.com. Didn't actually get a chance to install it yet, but next time I need to get things sagging in a specific way.... It was like $12 or $15.
Ah, that's a shame. There's no Convert option to fix the ploys, like with Smoothing? Is that also true for the end state of the physics sim?
I think the physics sim will produce the most realistic sag for stringing rope/cable between 2 points, but if the distance between end points is 10ft, the total cable length might need to be 11ft. Do I need to pre-bend an 11ft cylinder to fit between the points, or can the physics sim stretch a 10ft cylinder by an appropriate amount? (BTW, I learned the shape of a sagging cable is called a catenary - it even has a formula! http://home.earthlink.net/~w6rmk/math/catenary.htm )
There are quite a few ropes & cables I'll need to rig - services from utility poles, etc, flair on the side of buildings, bits of props and so on. (a lot of this is planning ahead, but I'm thinking about the workflow...) One idea I had for props was a bunch of market stalls with a rope of lights strung between them, so Diomede, your Christmas lights set idea is quite prescient :)
If you create a tube thing, and add bones, then bend it,. you should be able to export as OBJ,. (with morphs and skinning) (option)
then you'll get a bent tube object, which can be imported into carrara again,. without any bones.
You can also make the bend really easily by using an Interpolated curve, in the Vertex Modeller,. (pic)
this is three clicks (see grey line)
once you make the Interpolated curve,. it can be adjusted by moving any part of it,. it remains flexible and interpolates the curve as you move it.
Hope it helps :)
In certain cases, you can use the plugin “Sparrowhawke-Belt Pulley”.
You adapt the pulleys to your objects and you make them transparent, if you want…
The belt (round or flat) is automatically created by the plugin.
http://www.youtube.com/watch?v=445RPcqFm0Q
http://www.sparrowhawke3d.com/Sparrowhawke3DPlugins.html
Ah, that's a shame. There's no Convert option to fix the ploys, like with Smoothing? Is that also true for the end state of the physics sim?
I think the physics sim will produce the most realistic sag for stringing rope/cable between 2 points, but if the distance between end points is 10ft, the total cable length might need to be 11ft. Do I need to pre-bend an 11ft cylinder to fit between the points, or can the physics sim stretch a 10ft cylinder by an appropriate amount? (BTW, I learned the shape of a sagging cable is called a catenary - it even has a formula! http://home.earthlink.net/~w6rmk/math/catenary.htm )
There are quite a few ropes & cables I'll need to rig - services from utility poles, etc, flair on the side of buildings, bits of props and so on. (a lot of this is planning ahead, but I'm thinking about the workflow...) One idea I had for props was a bunch of market stalls with a rope of lights strung between them, so Diomede, your Christmas lights set idea is quite prescient :)
If you mean converting a Spline object to a vertex object, yes you can. Just select Convert to Other Modeler under the Edit Menu. If you're going to do that, it would just be easier to do as Andy (3dage) suggested and use the interpolated curve in the vertex modeler, and model in the Assembly room.
You can get some nice effects with rigging as well. My ShareCG account also has a rigged velvet rope done purely as a proof of concept for a discussion on the forum some time ago. Take a peak at it if you wish.
I've had a first pass crack at the handrail rope. This is a small stage prop, although I suppose it could be a jetty or something along those lines. I made 2 rope sections, using Andy/3DAge's interpolated curve technique - one for the flat sections, and one for the steps. I used inch and a half diameter rope (which is 38 mm in new money, although my brain hasn't really caught up with modern measurements!). The bend is slightly more complex on the angled section, since the rope has to exit the post perpendicular, and I didn't want it to be too floppy.
The two sections were, naturally, replicated to each post position as appropriate.
I'll probably make a brass rope-end fitting for the last post, rather than trying to model a knot (although it would be an interesting exercise...)
I'm going to try using a displacement map for the twist. I don't know how it'll come out - suck it and see, I suppose. If it looks naff, I'll have to think about modelling it. But that's for another day :)
Dynamic hair... now that's an interesting twist!
Dynamic hair... now that's an interesting twist!
Got the idea from Stu when he used it for a felt looking Fedora in a gangster picture he did.
Your model is coming along nicely.
Carrara has a pretty good bump function. Most rope has a pretty tight spiral. A bump map may be sufficient for the texture.
Tried using physics on a long cylinder with many sections - gravity -50m. Exported as .obj at position end of sim, with morphs and skinning and brought it back - worked rather well :)
That looks good - I shall give it a try later. Did you attach the rope to the posts at both ends?
Yes...gave it two attach modifiers :)
This was done using a variation of what 3DAGE suggested. Since it is supposed to be wire, I didn't want a smooth sag, but I did want it to be relatively easy to create separate pieces that could be assembled across an uneven landscape. It is for the challenge so ignore the rest of the elements that need retexturing, etc.
Cool. If you have the time, it would be good to put that is the thread as a WIP image. My guess is that the whole section is filled in along the path in the VM?
My first try at physics was not too successful - great if I wanted flimsy cloth, but not for solid rope! I've tried adjusting the sliders, but with little difference - guess I just haven't found the right one yet!
Thanks. I was reassembling everything for my last Challenge WIP for this entry when I realized that there was another thread devoted to this kind of thing. I should be able to post the challenge WIP tonight if all goes well. I took a lot of things out so I could work on different pieces without the clutter, and because hair and replicators tend to slow things down, in my experience.
@Tim. You may already be aware of this, but just to make sure, there are two areas where there are useful settings for the softbody physics. One is the Modifiers tab, which includes the specific soft body settings. You might also want to take a look at the Effects tab, which includes density, bounce, and friction presets for different materials.
Ah, thanks - I wasn't. More sliders to play with! :-D