Instant Terra

Exposing parameters

You can expose parameters that will be used to control the way Instant Terra creates or modifies a terrain.
Any parameter of any node of the Instant Terra project can be exposed, including terrain size and resolution.

Adding a Houdini parameter in Instant Terra

To expose a parameter, right click on the track bar of this parameter to open a contextual menu and select Edit in Houdini.

edit in houdini

A Houdini parameter node is automatically created and linked to the correct connector of the node.

houdini parameter

The Houdini parameter node is initialized with the name of the parameter and its full range (for instance, -180…180 for an angle).
Its default value (when exposed in Houdini) is the current value of the parameter.

houdini parameter settings

You can change the node name, the minimum and maximum values (for instance if you want a smaller range), and the default value.
You can expose as many parameters as you want.

Note: The Edit in Houdini entry in the context menu is available only if there is a Terrain to Houdini node in the project.

Resetting parameters in Houdini

Save the Instant Terra project, go back to Houdini, and click on the Reset parameters button to refresh the parameters.
The node now has the parameter that we have exposed.

reset parameters

Note: If you forget this step, the number of parameters in Houdini and in Instant Terra will not match and an error will be shown when cooking the node.

parameters error

Modifying parameters in Houdini

If Auto cook is not checked, click on the Cook button to compute the terrain after you have modified the value of one or several parameters.
When Auto cook is checked, the terrain will be computed again each time the value of a parameter changes.

Adding a Houdini on/off parameter node

If the parameter to expose is a check box, a Houdini on/off parameter node is created.

on off parameter
houdini on off parameter
on off parameter settings

Adding a Houdini on/off parameter node

If the parameter to expose is a combo box, a Houdini list parameter node is created.

list parameter
houdini list parameter
list parameter settings

You can remove some values from the list if you do not want to expose them.

The parameter is displayed as a combo box in Houdini

list parameter in houdini

Controlling the order of the parameters

The positions of the Houdini parameter nodes in the graph of the Instant Terra project are used to determine the order of the parameters in Houdini.
To change this order, you simply have to move the Houdini parameter nodes in Instant Terra.

parameter order 1
parameter order 2