face normal help

[wang_zichuan]

Hello all

I have a question .Please see the picture and the mov ，I want to make the primitive normal x direct to the other round loop, so I can rotation the face .

please,give me some ideas .

thanks

rot.mov

[LaidlawFX]

For your points you are copying with, drop a point sop down, and under the particle tab use the upvector. set it to add and delete the channels and put 1 in the y axis channel.

[wang_zichuan]

Thank you LaidlawFX .

The points have the right normal as you said.

but about the animation I still have problems.

I want to put the every primitive pivot to the root ,make them open like flower open. Are there some expressions like $BBX , $CEX .. to calculate the root.

and It seems dosenot work to use the surface node primitive as template to rot every piece open.

please give me some ideas,thanks!

[LaidlawFX]

there is centroid() to grab from other nodes, and you can use $CEX, $CEY, $CEZ .... if you use a for each loop sop and set it to primitive you can find the centroid of each face and rotate based on that. My brain isn't clicking on what you exactly want.

So here are the standard variables you could look up too

http://www.sidefx.com/docs/houdini11.0/nodes/sop/standardvariables

Maybe center of mass is what you are looking for? comx, comy, comz

If you get the example LayerOGL.hip from here and just replace the ogl stuff with your transforms animation that could help, too. since it is the for each loop as mentioned above, playing around with the transform axis sop

[wang_zichuan]

Thanks for you time LaidlawFX!

Here is what I want to do ,I want each primitive rotation along its own direction,and finally form the object.

You can see all the primitives rot the same direction,that is the problem!

In this project ,I use the point which the each primitive center as primitive node's template ,to transform the rot scale....

In some case,object like cube ,I can use the group node to separate four group according normal direction. But a random object,rotation is the problem!

[Macha]

Wang, does this help in anyway?

If not, I think what you really want is a unique coordinate frame for each primitive, aligned correctly. I tried some things but I think it depends a bit on the geometry. Tricky.

randrot.hip

Edited March 29, 2011 by Macha

[LaidlawFX]

Thanks for you time LaidlawFX!

http://www.vimeo.com/21596322

Here is what I want to do ,I want each primitive rotation along its own direction,and finally form the object.

You can see all the primitives rot the same direction,that is the problem!

In this project ,I use the point which the each primitive center as primitive node's template ,to transform the rot scale....

In some case,object like cube ,I can use the group node to separate four group according normal direction. But a random object,rotation is the problem!

Wang that building animation is a single grid(maybe a couple) copied to all those points. That set up is different than the set up of the sphere and marc's teapot, by me and marc's first estimate. The closest thing you could do to repeat that on the sphere is take a box/tube and taper(twist), or distort by grabbing groups and tranforming them into smaller sizes, into a sphere in order to make it appear like it is directly a sphere object that did the animation, too. That way you can guarantee to get a mid point at the bottom of the grid to unfold. Then you can copy sop it to kingdom come.

One node you can use is the point sop and plug your undistorted object on the left and on the right input plug in your distorted and plug into position tx2, ty2, and tz2. You can do this simple in vops sop too if you are feeling ambitious.

Good luck on your hmwk. I miss those assignments. lol.