convert wires to normals

[rohandalvi]

hi,

I was reading the Article on troll Hunter at Sidefx, and in that they mentioned that they generated lines on the body of the troll, converted them to wires to calculate dynamics and then converted the movement of those wires into the normals for the base surface to direct the movement of the objects attached to the main body. I am posting a paragraph directly from the article

"The vegetation presented more of a challenge as it had to be dynamic as well as dense. With the final troll there are 40,000 dynamic instanced objects set up on the creature. In order for all of this to simulate within a reasonable time frame, the team simulated a wire on each instance point and using the direction of the simulated curve to aim the instance direction. Simulation time was approximately 10 seconds per frame for all the vegetation."

How exactly is that possible.

The basic test that I did was to take a bunch of 2 point lines and copy them onto a grid. Convert them to wires, pin the roots, and animate them using a fan DOP.

Now the question is how can I convert these to normals for the grid. If that can be done, then I could copy any object onto the grid later and have it look like there is wind blowing through them.

Any help would be most appreciated.

I am attaching the file that I made.

with regards

ROhan Dalvi

wires to normals.hipnc

[Macha]

You mean like this?

N.hipnc

[rohandalvi]

Thanks a lot Macha,

Thats exactly what I wanted. sadly my maths is not that good. I can figure out the basic trigonometry stuff, but vector mathematics goes a little over my head. I am studying it, but it will still be a while before I can actually start using it in production.

But, thats why I love this forum, because people like you are always there to help.

If possible could you just explain the math behind this. I know it's a small network but I would like to understand what exactly is happening.

with regards

Rohan Dalvi