# why does my particle animation react like that?

So i have made a simple ring, gave hair to it and an object.

And it simulates like this:

And i have no idea why?

Why isn't it just hanging down?

https://www.dropbox.com/s/24s22xyzrx058c4/particle_hair_physics_probl.blend?dl=0

## 2 Answers

The hair direction is Y-axis of your object direction,similar to the bone in pose mode. in pic1, the object direction is (0,0,0) downwards,means -Z, and the face normal is out,they can't match.So we first rotate it to Y-axis,apply the rotation.And then,try to make the faces whose normal is the direction we want,so I make a circle,facing downwards,that's ok.

• do you mean like so? [1]: i.sstatic.net/f7Orf.png. doesn't help. And the origin was at the end of the line.... and what do you mean with "turn direction to z"? Commented Mar 12, 2022 at 12:43
• I can make it,I just editing my answer,but gif is alway over2M, that's waste many time. Commented Mar 12, 2022 at 12:44
• i don't need a gif, but an understandable answer....and i don't understand what you mean. Commented Mar 12, 2022 at 12:46
• pasteall.org/blend/354b9a7673984c60bd6e31ce428c3520 in your file,the origin is not at the end of the line, and the hair direction is related to the normal direction. Commented Mar 12, 2022 at 12:48
• but you are still claiming wrong things in your answer which everybody can approve who downloads my file - which wasn't ever changed of me. Commented Mar 12, 2022 at 13:11

This answer is for Chris's extra request shown in the comment.I tried many ways,but no one is both perfect and simple,I'll show my ways in brief,it all depends on what kind of result you want.

1. Simple and almost Perfect:
Just increase the segment of hair,cause you don't need thousands of ball,so add the segment to a big number(40 is almost looks good) will not cause too much exhaust.Only the direction of hair root is fixed,others will have much influence by gravity.
But,it's not perfect,cause if you watch close,the rope is not absolutely vertical,but I think it's OK for your purpose.
I have thought about changing the direction of normal,to fix the problem thoroughly,but I find something strange,it waste me much time.
I can only change the normal of line(edit mode-Alt+N),but the hair direction is only related to the normal of faces or vertices,as you can see in Particle System,which I can't change.Any one could help to tell me why?

2. I make a chain to control the ball,chain is made by cloth,but need a little more work.It can show the filament in detail, but I think you don't need that.The problem is,I don't know how to bind a heavy ball to the cloth which makes the whole system looks real.
.blend