Deborah R. Fowler
Nodes | Creep (and example of SOP Solver)
Posted: May 21 2020 Updated: May 21 2020
Tags: creep, sop solver
The creep sop can be handy for moving geometry along a curve without using a path constraint follow.
A student wanted to pause the creep so I created two examples from two methods I thought possible (in Houdini there are many ways to solve a problem!)
- procedural pause using expressions (this is a cycle)
- sop solver pause (giving more control)
The first method is the same as the method described but modified
for the creep sop controls on the Start N Stop page.
The second method involves the sop solver to keep track of the
previous value
In the diagram below as the green dot passes over the magenta grid it causes the animation to pause.
In order to achieve this we need to know the value of the animation when it stops so we can start it again. We can do this with a sop solver. We also need to take into account how long it pauses as we want it to start at the paused position. The network is shown below:
I have set up the control point to move on a sin curve but this can be any control. The important nodes are highlighted in red. Inside the SOP solver I have saved the attribute "creep" that I created in an attribute create node.
Inside the SOP Solver, the attributes prevcreep and creep are tracked. The number of frames that the pause takes is recorded so that the animation can be adjusted and not have it start at the time that has passed. Outside in the geometry level the new value of creep is assigned taking into account the pause in the animation.
Below is an example with noise driving the control add node:
