Can anybody tell me how to slow down time in Houdini ?
For example I have some fractured objects that when are crashed into time slows down on impact.
kind of like this video I did with C4D - http://www.vimeo.com/22368869 [vimeo.com]

when importing your objects (by fetching them from DOPs) apply a timeshift SOP afterwards. You can change playback speed by altering the Frame parm, for example: $FF/4. Turn Integer Frames off.

Now your sim should play back @ a quarter of the original speed.

You'll need a timeBlend node as well to create the “inbetween” frames…

If you are using dynamic fracturing then the Time Shift followed by Time Blend SOPs won't work on those frames where new geometry is being introduced.
If you pre-fracture the geometry, then this technique will work for the active simulation objects but NOT for the keyframed passive static RBD objects.

Since this effect requires everything to be slowed down, including the driven passive RBD objects doing the colliding, probably best to run the sim at the slowest speed then speed up the beginning part to full speed by culling the inter-frame geometry. This the Time Shift and Time Blend SOPs can do quite nicely with auto-fractrued geometry as there is no inter-frame blending going on.

To globally slow down the entire Houdini scene file, you can change the fps rate either by using the fps command in the textport or use the Global Animation Options dialog accessible by pressing the far right icon to the right of the playbar. I changed the default 24 to 384fps or 8x 24fps.


I then animated the Time Shift SOP to control the playback speed. I did this in the font sop object and channel referenced equivalent SOPs in the sphere retime object. I couldn't retime the original sphere in my file because I put the animation at the object level.