Preventing mountain sop from animating...

[psyence88]

Basically I’ve defined two points using add SOPs, merged them, created a line out of them with an addition add SOP, resampled, and then put it through a mountain SOP. When I animate one of the points, the mountain tends to freak out from what I assume is a lack of normals, I’ve tried a few things with the point SOP but I haven’t gotten anything good.

Any idea of how I can animate a point without the mountain SOP animating the line? I could animate the line itself, but that defeats the purpose of having a dynamic line to work with. Any help would be super appreciated! Thanks.

[Macha]

Animate after you use the mountain sop?

[psyence88]

No sir, animating a point upstream from the mountain SOP, is that possible?

EDIT

I’ve attached an example, basically, I would like the wire to animate as such without it spazzing out like crazy, any ideas?

line_wire.hipnc

Edited November 6, 2012 by psyence88

[Macha]

You could probably store the amount of displacement in an attribute and use it later to displace, but there may be some issues with transforming those attributes. It's worth a try.

[magneto]

It's because the point normals are not consistent from frame to frame. Add normals using a Point SOP before the Mountain SOP and then set it to something fixed like 0, 1, 0 or calculate it using the first and last point in your line.

[psyence88]

Thanks for the replies guys, I’ll try storing it into an attribute and see how that works out. Ryan, I’ve initially tried the point SOP to add the normals manual, I’ve also tried splitting the stream temporally by offsetting one a frame and subtracting its point positions in the normals parameters of a Point SOP, that did work somewhat, but it was still fairly erratic.

I am basically trying to emulate the effect of lightning arcing by using a CHOPs network and the offset parameter of the Mountain SOP, but the glitching/transform caused by erratic normals ruins the effect, another question would be if there are any alternatives to a mountain SOP? Perhaps there is a workflow in a vop SOP? Thanks again, really appreciate it.

[magneto]

If you are trying to do lightning, have you tried the Jitter SOP? That should be more erratic but at least it should be continuous instead of random flipping.

[michael]

there is a preset in the L-System SOP for lightning

[bloomendale]

It's because Mountain SOP uses current P as an argument of the appropriate noise func. So every new P of the point results in the new noise "offset" from the straight line.

You can alter slightly vex code of the Mountain SOP or use VOP SOP imho.

[sadhu]

Here is one of the solutions.

line_wire_soln.hipnc

[psyence88]

Hi Sadhu, clever workaround, but it doesn’t let me animate the noise itself, which is necessary for the effect.

I’ve attached my solution based on the replies in the thread. The solution meets my basic needs of what I’d like to do, using a VOP SOP and point SOP.

line_wire_sol.hipnc