Network and parameters

In Houdini, geometry, dynamics and particle setups, characters, object parenting, render dependencies, and most other things are defined by networks of nodes. Nodes are the building blocks of the scene. The network editor pane is a window into the hierarchy of node networks that define a Houdini scene. The parameter editor pane lets you edit the options available on each node.

Using the shelf tools often results in Houdini automatically creating nodes. For example, when you click the Box tool on the Create shelf tab, Houdini creates a new Geometry container object with a Box node inside. You can also create nodes manually in the network editor. This is how advanced work is often done in Houdini. Pressing Tab in the network editor opens a menu of all nodes available in the current network type.

Each node in a network performs a specific function. In geometry, particle, compositing, and CHOP networks, each node creates or modifies data passing through the node. At the scene level, nodes represent objects (such as props, bones, lights, and cameras) with transforms and parenting relationships. In the render network, nodes represent rendered outputs (images or animation), and links between the nodes define render dependencies.

Parameters are the options on an individual node. For example, each light has a Translate parameter that controls the light’s position, a Light intensity parameter that controls how bright the light is, a Color parameter that controls the color of the light, and so on.

Some nodes can contain other nodes. For example, a Geometry Container object node lives at the scene level. It contains a network of surface nodes that define the geometry of the object. See node navigation for information on how you move inside and out of container nodes.

Nodes are connected to each other by lines called wires connected to inputs and outputs on each node. See connecting nodes for information on how you connect nodes together.

Nodes have flags, which are clickable areas of the node that perform various functions. For example, in a geometry network, the display flag defines which node represents the final geometry of the object. Clicking the display flag button on a node moves the display flag to that node (the flag is displayed as a solid color to show it’s on). Nodes in different types of networks have different flags that perform different functions when clicked. See node flags for more information.