FXWars! Catapult! (Trebuchet) : Westiemad


This is the small humble area when my work will hopefully take place, although this cloth and hair trigger simulation does have me a bit jumpy.


Mental notepad. (brain storming may not make sense to any readers)

Things to condiser during the simulation process.

Resolution of objects, naming, constraints, extensive testing on simple models to prove concepts.

Model, mostly done in its simple form, not that i’m a master modeler by any ways or means.

Textures, planar projections.

Dynamics, fields, hair or weighted CVs, possible dust, and maybe fluid effects (cause they look nice).

Main things to look into, unhitching of the rope, could be tricky. Cloth holding sack, either cloth, or softbody with a wrap deformer and some low res version for collision detection.

Software: maya 6


Note, sort out the crappy facets on render, they are new since i broke mental ray playing with it last night. I know its not a good render before you tut aswell.


ok, originality is not my strong point. Its a classic boring one.

To do - rig up arm so it swings


    - simulate rope

    - come up with some funky ideas

    - finish the actual model before doing any of the above.


ok i did a quick test to try and get the motion of the main arm right, so feedback on this would be nice. Next simulate ropes and pullies. I haven’t played with dynamics in years.

To think of, way of winding down arm and attaching hook, (for look only).

http://members.lycos.co.uk/westiemad/blast1.avi (1.12mb playblast)


that is freaking unbelievable.

Very VERY nice job.

I wish I could make mine like that.


I can help you make one if you want? It wasn’t as hard as I’d thought, although I tend to bark up the wrong tree for a while. If you have any questions m8 i’ll help as much as I can.


ok, have made something to throw, it was rope, but they also made brackets on a ball obect, so i’ve done that, its no simpler just different. Here is the render for throwing the object (it doesn’t go as far as it looks, e.g. its not an ICBM)If this was a real catapult I’d have smashed it to bits twice and killed the blokes loading it with a few miss fires, still as long as i didn’t get hurt…


Still to do:
Ropes, particles, enviroment, object to hit. “Tart up catapult”.


Looking Good :slight_smile:

I want to see it knock something big down!

BTW… I added you to my buddy list on Yahoo Messenger.



That ball strikes me as falling very slowly? Eh, not that I got my dynamics all proper either so I’m not one to talk. I just… ah… think maybe it falls too slowly? :slight_smile: Or the scene scale is bigger than I think, that could be it.

Other than that, looks good. I’d suggest concentrating on the physics first, then the model later, because just getting the dynamics all nice and solid will take work.


i think it might be the angle of the shot and the way its thrown, I started to make a sort of tower thing, not finished but u get the general idea.


Hey man, put a lot of thought and R&D into your wall destruction before building something too elaborate there. If you try to run a simulation with a ton of bricks and want them all to be rigid-bodies, you will end up calculating for a year! I ran a simple test with about 300 bricks and a simple ball and I couldn’t even get past frame 2 (I waited about 15 seconds and decided it wasn’t practical). Your best bet will be to have a number of proxy objects that are collision objects, maybe 50 blocks tops. Have a collision event that says when they are hit, they bust up into smaller, instanced rocks that go flying. This will likely be the method I’m going to end up using but I figure before you put much time into a big elaborate tower, I’d warn you about the calc time.


they won’t all be on the same collision layer, but I understand totally what your saying. I blew up a columb into bits and it took a night to render the 10 second shot. That is a complex as I think I’ll make it, and not all the blocks will be seperate, depending where i get the ball to hit it, i may combine a lot into 1 object. I chose the tower to be semi smashed to bits already to lessen the amount of work needed to do. I’m sure when i actually get round to having to make the simulation I’ll PM you with a “you were right”.

Thanks for the feedback tho, and await that PM.


ok 10 mins this morning on the projectile. Not finished, but its a different. Can you guess what it will be when its finished?


I can’t remember the name of them, but when it is finished that thing looks like it will contain a (clay?) pot with oil and a wick, so it will explode on impact. If I’m right, then you will know what I am talking about :wink:

And looks good!


pretty much, its gonna contain a fire, which can then happily streak across the sky. I might change it slightly tho.


trying to be a bit more adventurous (sp) this time, I’ve made a new catapult this time its on wheels, apparently wheeled ones through a third further? I will teather it to the ground using ropes, but will allow it a bit of movement.


Awesome man, wheels is the way to go! I am going to commence building my final model tonight and going to put wheels on mine as well. I don’t know if the dynamics sims will accurately transfer inertia all the way down through the model (the entire model will have to be a rigid body or multiple rigid bodies) or not but it should be cool to see how it works out. Post some more details when you get to the dynamic part.


Your catapult looks good and i cant wait to see the fireball across the sky.
The reason the wheel thing works is that instead of waisting energy on the ground you use the hevyer weight at the “front” as a propelat for the catapult (PS: it will get back, but then the ball is fired and wont be affected by it) and therefor gives the ball extra speed. This will not work if the ball is to heavy (I think) because then the force will be equal.
Good luck!


Looks good! The wooden boards are awesome.