I am trying to move my boat within the tank because I figure that I can get a more detailed sim and a longer wake trail if I can move the boat to the front of the tank… but when I break the connection to the “center” on the wavetank, the simulation and boat no longer move together. Is there a way around this? Sorry if I am missing something.

Yes excellent question! It requires you to “Houdini finesse” a couple parameters. Common to do for the off the Shelf tools.

There are centroid() expressions in there to determine the position of the container based on the centroid of the tracking object. I am always offsetting the container btw so a common thing to do.

The Ocean Source SOP in question is called wave tank and the channels to manipulate are in the parameter labeled Center and the two channels are called tx and tz.

You can simply put your own offset float values in front of the centroid() expressions:


which will offset the container 0.2 units in X and -0.5 units in Z from the centroid of the tracking object.


Tip: you can use the MMB (Middle Mouse Button) on top of the .2 or .5 in the expressions above and increase/decrease the values by manipulating the ladder handle to place the container interactively while watching in the viewport.

I must use the MMB on values in expressions at least every few minutes if not more frequently when building up assets and Houdini networks as I go. So this is a very common TD technique to use when wrangling with expressions.

There are other approaches to incorporate Nulls at the object level, add your own point to locate the centroid of the container within the tracking object or other techniques to fetch the tracking centre but a simple offset on the expressions works just fine once you know about the MMB trick over values in expressions.