Learn the ropes - Dynamic rope simulation in Poser?

  • There are various kinds of rope figures available for Poser, mostly using individually poseable parts and sometimes "easypose" settings for general bending, spirals, etc.. Who ever tried to bend such a rope into a complex shape knows about the hassle involved. And you always have to guess how the correct shape would look like in your scene and bend accordingly. I am not doing animations, but for these it would mean even more tedious work!

    Wouldn't it be cool if you could just make a rope, hose, wire or cable react to the objects in your scene like in the real world? Wouldn't you like to be able to hang a rope between two buildings and let your hero glide down on it using the old rubber-chicken-with-a-pulley-in-the-middle and the rope bends physically correct? Or let your character hold one end of a rope in his hand and the rest curls on the ground like it should? Or even make him skip a rope or shoot a grappling hook with a rope attached?

    Not having found any hints on the web, I came up with the idea to use the built-in Bullet physics to simulate a rope. Good old Andy is supposed to hold a rope in his hands that drops from a few centimetres above and it should just bend like a real rope does.


    Mind that my interface units are in centimetres.
    I put Andy in the scene and as my rope I created an elongated cylinder from the morphing primitives (more polygons than the normal cylinder) which I subdivided twice. I set Andy's hands and arms as choreographed objects and the rope as the only soft dynamic object.

    I tried various combinations of the parameters involved, but the rope always jumps around, bends not very rope-ish and finally jumps off the screen at the end of the simulation. The screen shot shows the last frame before it jumps into nirvana. More internal pressure leads to an inflation, less to a flattening. And the end caps always come off (marked red). Bummer!

    I also tried another simulation with rope and ground alone where I added a self-constraint to one rope cap to let it hang down on the ground. As soon as the loose end hit the ground, it started to jump like crazy and disappeared.

    Summary: My attempt to turn a cylinder into a rope using Bullet physics completely failed. A brief try with the cloth simulation was even worse.

    Question: Is it somehow possible to physically simulate a rope in Poser at all?

  • First, check to see if you have enough polys along the length of the rope, what would be the Y axis in zero position. When I set it up, that one seems a little big for what you want. The rope will only bend at the edges of each poly. Try 4 or 5 subdivisions.

    If that doesn't help, you might try adding some animated constraints to the ends of the rope to tell it where to go.

  • I've certainly done it with cloth simulation before but as @redphantom said, you do need lots of polys to do it properly. I've also done it with chains, for that I have a simple ribbon that I simulate then export the ribbon to Blender and convert the outer edge to a curve, then create a chain link and use an array fitted to the curve. If you have a cylinder and cloth sim it, the "rope" will tend to flatten. Which is why I would do something similar to what i described with a chain if I were doing rope.

    Also check out http://www.morphography.uk.vu/~cagepage/looper/loopy.html which has some automated riope / chain / loop creation scripts


  • @amethystpendant Wow, that Mr Looper page looks pretty awesome! I will try it out as soon as I got some time on my hands.

  • I managed to get necklaces working quite nicely in the cloth room, so you might find something useful in this thread if you want to try the cloth room route https://forum.smithmicro.com/topic/1517/experiments-in-creating-necklaces-etc-for-use-in-poser-s-cloth-room

  • @amethystpendant Thanks for the link to the quite elaborate article.
    I mostly understand what it's about, but it seems like this will not help me to find a way to easily use dynamic ropes. I looked at the web site of Bullet physics and I saw that there was a simulation type "rope" added some time ago. Maybe this is needed for this special kind of object. I presume this did not make it into Poser, though.

  • I do not know if anyone has used this physics plug in in Poser Pro 11 But I would love to know:


    There is a really nice chain turning on cog animation showing it in action:

    Has anyone used this?

  • Well I tried to figure out how to do this myself with the built in Physics so far I have got this:
    0_1494067457174_Screen Shot 2017-05-06 at 6.43.04 AM.png
    It hangs nicely I used 16 cubes flattened to 10%. I made them rigid objects, and I had to use 2 constraints on each. With only 1 constraint they would twist around. It took me about an hour or 2 to figure out how to add and correctly position the constraints. Then the 2 cilinders are choreographed objects. I let it hang a little more so I could also visualize how a hanging chain would look.

    They next step will be to do the animation.

  • @david_macrae Looks interesting, but to me it seems the physics plugin was like Bullet Physics before it was built into Poser 10 / Pro 2014.

    Your approach to do the same with Bullet looks great! Maybe to get my rope done, I should connect short rigid cylinders with hinges instead of treating the rope as one large cylinder...

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  • Yes I think they must have just bought it and incorporated it. Anyway I was thinking the same thing as I tried using one long cylinder for rope and it did not work out too well for me. Anyway here is the animation. Took the above and added one animated target to the first block them moved it in a circle with 6 keyframes and ran the sim.

    alt text

    Click on the imaged to see the animated gif.

    Tomorrow I will try for rope I just had a power outage. A tree fell on a power line.

  • OK back to this. I used a dynamic easy pose rope in my library. It was a figure with 100 bones in it. I believe it was a freebie. This is what I like in bullet (it does not need to be a prop like cloth sim.

    Anyway it is fairly easy once you learn the trick. Set up a new bullet sim. select objects, select soft dynamic and check rope.

    Then go down object select rope and constraints tab. Select paint icon and select it. Select weight and set it to .002. then go down to set all click it and select set all to target weight.

    Then go back up same panel and select more constrained and lightly paint two ends.

    Run sim. (I usually check live sim to test then unselect it clear sim and then run)

    0_1510728134541_Screen Shot 2017-11-15 at 12.53.17 AM (2).png

  • For the original poster instead of painting the ends you can paint where andy's hands are. then you will have to select more dynamic and paint the ends.
    0_1510728242404_Screen Shot 2017-11-15 at 1.31.01 AM (2).png

  • dynamic rope test

  • The problem with "dynamic rope" is that it's very difficult at times to keep "tubes" from collapsing, since retaining a closed object's volume isn't what the dynamics engine is supposed to be doing. (Cloth property changes help.)

    What I want is an automagic end-point-to-end-point simulation in "real time." There is a script on Sharecg with accompanying geometry/controls that let's you set up a connection points for a "chain" and then input sin/cos/tan yada values to automagically drape the chain from point to point, naturally, more or less. BUT, it doesn't respond to intersections at all, so you'll impale various figures along the way...

    Then, there's a script by... someone, maybe Nerd3D, called "follow me" or something to do with "telephone cord" that allows you to "draw" in a python generated 2d display what shape you want ANY rigged chain to follow. The rig does not need to be anything other than a sequential chain of bones, so nothing fancy there at all and it'll take any rig like that, even those with no IK. Draw how you want the rope/chain to look and, walla, it'll conform to that shape. But, just in one dimension, IIRC. (You may be able to rotate it along another axis, haven't checked.)

    The "best" solution using "known" features that I think are accessible, with my limited knowledge, would be a script that simply created a phantom 2D rope between two points, with a variable entered for gravity intensity, and then ran itself, first, through the dynamics engine with it's simplified geometry and, afterwards, spawned a static-prop rope mesh with the desired attributes of thickness and density of mesh. If, which is also possible, it instead generated a rigged rope that was preset with the appropriate number of user-selected bones, for fine tuning later, and pre-posed in the dynamically draped position... that would be awesome. :)

    (Better yet, a "Make Do Rope or Chain" between two points, automatically detecting all collisions, draping accordingly, and then "make do" it with the press of a button.. Yeah, that'd be great. One that adds/stretches as needed and drapes in real-time, I'd pay real good money for that. :) )

    PS - Most popular solutions revolve around "chains" because you can just create one oval as a base geometry, assign that multiple times to an automatically generated, sequentially numbered, chain rig and you're done. You can't do that with a "rope" since a base object won't orient itself to "look good." The little tubes wouldn't be contiguous geometry and they'd look like a demented chain of pixie straws or something. A "chain link" does not have that problem.

  • More practice weight painting on a dress figure and hair. That can now be posed with keyframe animation then have physics simulation on top of that.

    @morkonan self constraint helps with the collapsing tubes. But it takes some tries to weight paint and get all the setting right. And it will be different in each situation. I think it is another good tool in the tool belt. Of course, the trick is knowing all the tools and where and when to use each one.

    for example I think this works pretty well for the dress and hair here. Also I originally was interested in the rope because I am planning a city destruction scene where buildings collapse as I sowed elsewhere but also I want a telephone pole and the wire to fall and this technique works well for that with self constraints and one end weight painted. Similar to the rope above but that had two ends painted not just one.

  • @david_macrae said in [Learn the ropes - Dynamic rope simulation in Poser?]

    knowing all the tools and where and when to use each one.

    I very much agree. I know too little of some of Posers more intricate tools. (Bullet Physics, mostly, and Superfly optimization.)

    I'd want it for much the same thing as well as some "cheap" physics simulations for objects I can then export to work with other programs for fine-tuning. Since I've got Poser, why not use it, right? (I'm reminded of things like some of Stonemason's work, both sci-fi and historical/contemporary, and that of others, especially works with lots of hanging wires and "vines" that could be simulated to do all sorts of things other than just... sit there.

    Imagine trying to get a jungle tree to "sway" back and forth and having to deal with vines... You can't just one-click create them or easily repose them, you need to have them react. Trying to do that using the Cloth Room would be... uh... That's like trying to launch a Space Shuttle with a starter pistol...

    (Note: It is possible, using IK and parenting techniques, to get ropes/vines to react to a point being moved. But, they won't drape by themselves, don't react very well and ignore "gravity" at all times... That's OK for some quick stuff, but not for something one is going to spend a lot of effort creating, otherwise.)

    for example I think this works pretty well for the dress and hair here. Also I originally was interested in the rope because I am planning a city destruction scene where buildings collapse as I sowed elsewhere but also I want a telephone pole and the wire to fall and this technique works well for that with self constraints and one end weight painted. Similar to the rope above but that had two ends painted not just one.

    It's not bad, just a little stiff. But, depending on what's going on, it could be fine. (ie: There's not much "momentum" and recursive movement with resistance/momentum/etc.) Actually, with a sassy expression, that whole stiffness thing to the movement could give it a nice feel.

    Curious - You mentioned a "dynamic Easy-pose rope." I know, basically, "dynamics" and "Easy-Pose" stuffs, but have never heard/read the two mentioned in the same breath. Easy-Pose is old stuff, but great, and uses the same geometry restrictions for grouping/rigging that most Poser content uses. It's just great for dumping in a lot of IK and maths stuffs for movement, I guess.

    Do you mean the Easypose rope is hardwired for some sort of dynamics simulation capability? If so, can you point me to more info on that?

    On its use in Poser Physics, does Poser Physics require "rigged" figures or could one construct a basic rope that follows conventional "dynamic cloth" restrictions and just use that with Poser Physics?