Houdini DOPs Keyframes 4
Channel: peter quint
Date: 30/01/2016

A look at how to combine traditional keyframe animation with DOPs simulation.
This final part shows how to calculate an acceleration value for the points, the use of the copydata solver, and using groups and a splitobjectstream node to switch between solvers during the animation. Finally it looks at how to eliminate excessive velocity in the dynamic simulation.
The project file for the final part of this tutorial is at sites.google.com/site/pqhoudinitutorial/

Spotted an error at 3.39 the in the second length expression I use oldvelz twice, when it should of course be oldvelx, oldvely, oldvelz (not oldvelx, oldvelz, oldvelz). I've corrected the project file.

I've uploaded a version that works in H11 (see DopsKeyframe_Houdini_11.zip). The issue here is that Houdini 11 added to the copy data solver the ability to copy between objects, rather than copy different bits of data within the same object. To replicate the old behaviour make sure source object is set to $OBJID and also that solver per object is enabled (otherwise all of the objects try to get their data from a single object rather than each referring to itself)

A comment about the vector length expression (at ~1:36): a simpler way of measuring lengths of vectors in dop that i found is writing in the following format:
vlength(dopoptions(...))
e.g.:
`vlength(dopoptions("/obj/AutoDopNetwork", "grid_3", "Position", "vel"))`