Hair problem


hi all xsi users! im having a headache with xsi hair. i browsed through the archived threads about hair problems and still couldn’t quite solve my problem, so here i am posting my problem for u all to help me solve together.

im creating a character with long hair (a ghost) and was trying out the dynamics bcos i have plans for intensive animation for the character. the problem is, the hair’s collision with obstacles are not accurate. lemme post some pics to show u what i mean.

here’s a pic of the hairstyle without animation.


and so i made a cylinder to be animated against the hair, but once i hit the set obstacle button and pick the cylinder, the hair immediately screws up into this form!


anyway, i found out that i could fix it by dragging the timeline indicator back and forth until the hair simulates back to its original style, but we can already see that the hair is beggining to be affected by the cylinder even b4 the cylinder makes contact with the hair! note the curve of the hair


as the cylinder moves closer to the hair, the hair seems to avoid it spherically b4 contact, sort of like a magnetic thingy… it’s really not what i wanted. if the collision with the cylinder looks like this, how is it going to react against it’s body later on?! please help, and tell me whats wrong!

the setting for the obstacle is actual shape, push length=0.1

help appreciated!


Choose “XSI” as the collision type in the hair PPG (instead of average sphere), and correctly set the collision body to “mesh” in the cylinder obstacle PPG.

Ciao, ¡muh!


thebigMuh, u r a problem solver. :applause:

thanx a lot dude… but what’s with the “mesh” thingy u mention? i can’t follow that… is that a new thing in xsi4? im using xsi3.5.1 …

and one more thing, how do i disconnect the hair from a certain obstacle? there’s no such function in the hair module. i tried using the disconnect from obstacle in the simulate module but it wont work. and it’s not likely i will delete the obstacle object, because in this case, it’s the emitter. any solutions?


K, the setting is “Actual geometry”, not mesh, I didn’t have XSI open at the time.

Just delete the *_obstacle property from your obstacle to get rid of any collisions.

Ciao, ¡muh!


And if you happen to need that obstacle for some other simulation object, you can just delete the obstacle property that exists under the Hair Generator Operator in the Hair object’s stack.


thanx, i’ve successfully removed the obstacle.

but now my newest problem is, i selected the polys of the head from which i want to emit hair, then extract from poly, and apply hair. next i hide the emitter and parent to the head, then set the head obstacle to the hair, now the hair should relax and react to the gravity and then collide with the head. in my case, i’ve part of the hair rest on the obstacle as result from collision(which is what i wanted) but i’ve also part of the hair wiggle about and keep bouncing off the head. as if the hair hasa life of it’s own, sort of medusa’s hair. lol… how do i fix this?

i already made sure that my hair does not collide throught the head in beginning of simulation. and i notice that the wiggling hair only occurs when the obstacle is near it, when i tried to move the head down, (the emitter is not parented this time so it stays up.) the hair collides correctly and never wiggles. why is this happening? anybody got an antidote?

thanx in advance.


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