How do I rig a bow string?
Hey everyone! I'm trying to make models for practice and to import into a game I'm making. I'm really sucky at modelling currently, so keep in mind that I'm not markedly advance and consequently don't know many of the advanced techniques/terms.
Either way, so I made this bow:
I'm trying to rig it. I followed this tutorial: http://elyzius.blogspot.com/2013/02/tutorial-rigging-bow-in-3ds-max.html and got to the wire parameter part, but after that everything seemed to be falling apart. I got the bones in the main bow figure to work and deform appropriately, but I can't seem to do the same for the bow string. I've been at this for around 5 hours but I've run out of ideas which is why I decided to just go ahead and ask. I looked all over google but didn't find any other resources I could use or replicate.
I'll take anything I can get at this point. The bow doesn't have to bend, getting the bow string to be able to pull back realistically will suffice as I learned how to rig the bow handle itself already I think. The results from mark dygert in this thread: http://www.polycount.com/forum/showthread.php?t=105385 look perfect but I can't replicate it. If you need any additional screenshots of different angles and whatnot please ask. Thanks!
Either way, so I made this bow:
I'm trying to rig it. I followed this tutorial: http://elyzius.blogspot.com/2013/02/tutorial-rigging-bow-in-3ds-max.html and got to the wire parameter part, but after that everything seemed to be falling apart. I got the bones in the main bow figure to work and deform appropriately, but I can't seem to do the same for the bow string. I've been at this for around 5 hours but I've run out of ideas which is why I decided to just go ahead and ask. I looked all over google but didn't find any other resources I could use or replicate.
I'll take anything I can get at this point. The bow doesn't have to bend, getting the bow string to be able to pull back realistically will suffice as I learned how to rig the bow handle itself already I think. The results from mark dygert in this thread: http://www.polycount.com/forum/showthread.php?t=105385 look perfect but I can't replicate it. If you need any additional screenshots of different angles and whatnot please ask. Thanks!
Replies
This is extremely simple, and it's the method I almost always use for bows and crossbows: http://www.polycount.com/forum/showpost.php?p=1668223&postcount=7
If you follow that thread closely, that pops up a few times. So really, I think you should do the 2 bone rig and not make it any more complex than it needs to be.
Or the string's made of feathers
Currently one bone controls the string deformation, one dummy controls the movement of the whole string, one bone controls the doformation of the bow base, and one dummy controls the movement of the whole bone. The last dummy controls the movement of the whole bow. I'm wondering if that's overkill and if it would be more efficient/better to make the bow move correctly in relation to the deformation so I could just attach the string to the bow, or if this is the way it's generally done.
The skin weighting (and the timing of the animation) isn't helping it at all. If you adjust the skin weights and smooth them out it will help quite a bit.
The one thing that the more complex rig does, that the two bones don't do, is collapse the end points. The second bone just brings the tips straight back and they stretch, but in reality they would move back and toward the center of the bow and never stretch.
In games and film reality and physical perfection are often suspended for many many reasons, it doesn't have be physically accurate to look right. Most of the time no one notices or cares and the lighter rig is much easier to work with.
"Why do our characters deform like ass!?"
"Well... I blew our entire tech budget on rigging up the bow."
But seriously you can get better results with what you have (and some better timed animation) before you take a step up to something more complex.
The next step you should take before jumping into solvers or lookAt's is to just use bones and rotate. If that doesn't work for you, you can apply HI solvers. If you get crazy anal about the string then you can use lookat constraints, but really, you shouldn't have to go that far.
I see, thanks for the advice
What do you mean with adjust the weights and smooth them out? This is what the colors of my weights currently look like
And for what you said about next step being using bones and rotating them, do you just mean making more bones and rotating them individually instead?
Also thanks again for the advice. I don't really need it to look excessively realistic because I'm going to use it for my game, and they're going to be pretty zoomed out either way. But I still want it to be at least decently good so I can get more experience.
The bow, realistically, doesn't stretch, which it does if you use Translation only in Mark's example (which isn't wrong); however, this isn't usually too noticeable and would be good enough to save on joint counts or whatever etc.
Instead, the bow should bend from being pulled by the string, therefore using new joints to rotate the bow's ends instead would be a more accurate presentation. Expressions and other tricks would make it easier so that the bow bends according to the string's pull and you don't have to manually rotate them.
Whether this visual improvement is worth it at the intended view distance, that's up to you.
Oh okay, thanks! I don't think it is but I think I'm going to try it later on anyways so I can see how it's done. Thanks a lot for the help guys! On to making a medieval character now!
Don't be scared of animating chains of bones in a case like this, its actually very easy to do. Select all of the bones, set your pivot to "local" and "use pivot point center" (the only option if you have autokey turned on) and then rotate the bones. Each bone will rotate from its pivot.
If you mirror the bones correctly (using bone tools) you can select all of the bones and both sides bend the right way, meaning you basically have one simple way to control the draw back of your bow.
You're not even using any expressions, solvers or advanced rigging, just simple bones and rotations, nothing heavy, nothing complex and damn near bullet proof, no one is going to break this rig unless they want to.
Hey thank you so much for helping me this long, and everyone else too! I did what you said and I think it's much better than what I had before. Again, thank you!
I still suck at this but thanks to you I've gotten a lot better than before! Here is the result: