Houdini 20.5 Networks and parameters

Organizing, customizing, and annotating nodes and networks

How to keep your networks neat and well documented.

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Routing wires with dots

You can use dots to make wires follow a specific route instead of just going straight from output to input. This can be useful for preventing long wires from overlapping other nodes, or to make organization of the network clearer.

See how to create and edit dots for more information.

Switching in networks

Often when you're creating networks you want to check the effect of a change, or switch back and forth between different versions of the network, to find problems or explore different looks.

Houdini includes several tools for switching parts of the network on or off:

Switch node

Most network types have a Switch node type that lets you choose which upstream branch of a network cooks. Often you switch based on the result of an expression, but you can also use a Switch and manually change the active input to quickly switch between different branches.

Bypass flag

Some network types let you turn on a Bypass flag on a node to make the node have no effect. For example, in a geometry network, a bypassed node passes the geometry through without modifying it.

Display or Output flag

A geometry network only cooks the nodes necessary to generate the node with the display flag. You can have a multiple branches of the network generating different outputs (for example, to allow to check the effect of different node combinations or settings), and switch between them by moving the display flag to the end of the different branches.

Rewriting

You can leave sections of the network disconnected and rewire into them to switch to them. This might be useful, for example, to keep an abandoned implementation around in case you want to refer to it later. However, if you're switching back and forth frequently, inserting a Switch node is more convenient than rewiring.

Customizing node shape and color

You can customize the shapes and colors of individual nodes to help make them stand out in the crowd, allowing you to locate them visually, especially when you're zoomed out.

To...Do this

Change a node’s shape or color

  1. In the network editor, choose Tools ▸ Show Palette: Shapes or Colors. (You can also press Z or C to show/hide the palettes.)

  2. Drag a shape/color from the palette onto a node, or select one or more nodes and click a shape/color in the palette.

You can resize the palette by dragging the corner.

Change the default shape/color for all nodes of a certain type

Hold ⌃ Ctrl when dragging a shape or color onto a node (see above).

Note that this any nodes of the same type that already have their own individual custom shape or color will keep them.

Customize the color palette

Right click a color in the palette to add, edit, or remove colors.

Changes are saved only for that pane on the current desktop. To make the current palette the new default, right click the palette and choose Save as defaults.

Turn off display of custom shapes

In the network editor, turn off View ▸ Show custom node shapes.

(You can also set the Use simplified shape when node shapes off option in Edit ▸ Preferences ▸ Network editor. This makes the network editor use a simplified rectangle shape when Show custom node shapes is off. This may speed up the display of extremely dense networks.)

Themes

You can create themes with customized node shapes and colors, and switch between themes.

To...Do this

Show the Themes tab

  1. In the network editor, click the Display Options button in the toolbar to open the Display Options window.

  2. Click the Themes tab.

Switch to a different theme

On the Themes tab of the display options, click Default node colors or Default node shapes and choose a theme.

For example, there is a No Color color theme, or a Flair shape theme that has more interesting shapes for Bone and Light objects.

Start a new color or shape theme

  1. On the Themes tab of the display options, click Default node colors or Default node shapes and choose “Duplicate current theme”.

  2. Enter a name for the new theme.

Delete a custom theme

  1. On the Themes tab of the display options, click Default node colors or Default node shapes and switch to the theme you want to delete.

  2. Click the menu again and choose “Delete current theme”.

Bulk changes

  • You can set the color or shape of multiple nodes at once by selecting the nodes and then clicking in the color or shape palette.

  • You can get or change custom node colors using the hou.Node.color and hou.Node.setColor methods with the hou.Color class:

    >>> n = hou.node("/obj/geo1/box1")
>>> n.setColor(hou.Color(0.996, 0.682, 0.682))
>>> n.color()
<hou.Color r=0.996, g=0.682, b=0.682)

  • Custom shapes are stored as “user data” on the node. You can get or change the node shape programmatically using the hou.Node.userData and hou.Node.setUserData methods:

    >>> n = hou.node("/obj/geo1/box1")
>>> n.setUserData("nodeshape", "tilted")
>>> n.userData("nodeshape")
"tilted"

    When the nodeshape user data is empty, or does not contain a valid shape name, the node uses the default shape for its type (set in the OPcustomize file, see above).

    An easy way to reset any node to its default shape is:

    node.setUserData("nodeshape", None)

  • The NodeType.defaultShape method returns the name of the default shape for a given node type. (If the default has not been customized, the method will return the empty string).

  • To programmatically get a list of available shape names, get a reference to a network pane tab and call hou.NetworkEditor.nodeShapes.

    >>> editor = hou.ui.paneTabOfType(hou.paneTabType.NetworkEditor)
>>> editor.nodeShapes()
('rect', 'bone', 'bulge', ... )

Network boxes

Network boxes let you group nodes together. This is useful when you can’t or don’t want to collapse the nodes into a subnetwork but you want to distinguish them from other nodes.

  • Moving the box moves the nodes inside with it.

  • You can use a network box to highlight a group of nodes.

  • You can minimize the box to hide parts of the network, or keep the network tidy by only expanding the parts you're working on.

For example you could group the nodes representing different limbs of a character rig in different boxes. Or you could put different distinct “stages” of a geometry pipeline in different boxes.

Tip

You can embed network boxes inside other network boxes, as well as sticky notes and images.

To...Do this

Create a network box

  1. Select the nodes you want inside the new box.

  2. In the network editor menus, choose Add ▸ Network box.

Give a network box a title

Double click in the top bar of the box to edit the network box title. This can be useful to annotate the box’s contents.

Add or remove items to/from a box

Drag the node onto or out of the box.

You can drag an item slowly toward the edge of a box to expand the box, or drag quickly to remove the item from the box.

Move or resize a network box

  • Drag the bar across the top of a box to move the box.

  • To resize a box, drag one of the corners.

  • You can drag an item slowly toward the edge of a box to expand the box, or drag quickly to remove the item from the box.

Resize a network box to fit its contents

Select the box and choose Layout ▸ Resize network boxes to fit.

Remove a network box

  1. Select the box.

  2. Do one of the following:

    • To delete just the box and leave its contents behind, choose Edit ▸ Delete or press ⌦ Del.

    • To delete the box and its contents, choose Edit ▸ Delete with network box contents or press ⇧ Shift + ⌦ Del.

Minimize and restore network boxes

You can collapse a box down to its top bar to save space or create a cleaner look when you are not working on the box contents.

  • Click the minus button in the sticky note’s top bar to collapse it. Click the button in a collapsed sticky to restore it to regular size.

  • If you hold ⌃ Ctrl and click the minimize/restore button, the editor will move other nodes around the netbox to account for its new size.

Assign colors to network boxes

  1. In the network editor, choose Tools ▸ Show Palette: Colors to show the color palette.

  2. Select the box and click a color, or drag a color onto the box.

Manipulate network boxes using Python

Network boxes have an internal name you can use to script them, but it’s not displayed in the network editor (the text in the netbox title bar is actually the netbox’s comment string).

  • To create a network box, call hou.Node.createNetworkBox on the parent network.

  • To manually get a reference to an individual netbox, drag the network box from the network editor into the Python shell.

  • To get a reference to a netbox by name, call hou.Node.findNetworkBox on the parent network.

  • To get a list of all network boxes in a network, call hou.Node.iterNetworkBoxes on the network.

  • To get the selected netbox(es), call hou.Node.selectedItems (not selectedChildren, which only returns nodes) on the parent network and check the class of the items in the returned list. For example:

    network = hou.pwd()
selected_boxes = [item for item in network.selectedItems()
                  if isinstance(item, hou.NetworkBox)]

  • See hou.NetworkBox for methods you can call on a netbox object.

Sticky notes

Sticky notes are boxes of text in the network. You can use them to explain parts of the network to other people working on the network (or to your future self!).

To...Do this

Create a sticky note

In the network editor, choose Add ▸ Sticky note, or click the Add sticky note button on the toolbar, or press ⇧ Shift + P.

You can drag the sticky note to move it where you want in the network.

Edit the contents of a note

Click in the body of the note to make the text editable. When you're finished editing, click outside the note.

Resize a sticky note

Drag one of the corners of the sticky note.

Minimize and restore sticky notes

You can collapse a sticky note down to its top bar to save space or create a cleaner look when the sticky is not needed. Click the minus button in the sticky note’s top bar to collapse it. Click the button in a collapsed sticky to restore it to regular size.

Change the size of the text in a note

  1. Right click the note to show the context menu.

  2. Open the Set text size submenu and choose a size.

Change the note colors

  • In the network editor, choose Tools ▸ Show Palette: Colors to show the color palette.

  • Select the note and click a color, or drag a color onto the sticky note’s top bar, to set the background color.

  • Drag a color onto the sticky note’s body to set the foreground color.

Delete a sticky note

Select the note and choose Edit ▸ Delete or press ⌦ Del.

Manipulate sticky notes using Python

Sticky notes have an internal name you can use to script them, but it’s not displayed in the network editor.

  • To create a sticky note, call hou.Node.createStickyNote on the parent network.

  • To manually get a reference to an individual note, drag the note from the network editor into the Python shell.

  • To get a reference to a note by name, call hou.Node.findStickyNote on the parent network.

  • To get a list of all notes in a network, call hou.Node.iterStickyNotes on the network.

  • To get the selected note(s), call hou.Node.selectedItems (not selectedChildren, which only returns nodes) on the parent network and check the class of the items in the returned list. For example:

    network = hou.pwd()
selected_notes = [item for item in network.selectedItems()
                  if isinstance(item, hou.StickyNote)]

  • See hou.StickyNote for methods you can call on a netbox object.

Using sticky notes as big labels

You can turn off the background of a sticky note to create the appearance of a free-floating label. These labels can be useful to annotate large-scale sections of the network. Making the text large makes the labels visible at far zoom.

  1. Create a sticky note and type a (short) label in it.

  2. Resize the note so it just fits the label inside.

  3. Right click the note and choose Set text size ▸ Large or Extra large.

    or

    Hold ⇧ Shift and resize the note to resize the text at the same time.

  4. Right click the note and choose Hide background.

Collapsing node branches

It’s possible to collapse a node branch down to a small stub representing the branch on an input. Parameter nodes for promoted parameters on VOP shaders start out collapsed to keep the network cleaner. You can select the nub to select the hidden Parameter node it represents.

  • Selecting the stub is the same as selecting the nearest collapsed node.

  • Double-click a stub to expand the collapsed branch.

  • To collapse the inputs to a node, right-click the node and choose Inputs ▸ Hide inputs.

Hiding nodes can make the network harder to understand for other users if they don’t notice part of the network is hidden. You might want to use other organization tools (such as collapsing network boxes) to clean up the network instead.

Working with subnetworks

Subnetworks let you encapsulate multiple nodes inside a single node, streamlining your network visually and conceptually. Note that putting nodes inside a subnetwork changes their path.

The subnetwork node can have up to four inputs, which are passed down to special nodes inside the subnetwork.

To...Do this

Create an empty subnet

  • Use the tab menu to create a Subnetwork node.

Create a subnetwork from existing nodes

  1. Select the nodes you want to go inside the new subnet.

  2. Right click one of the nodes and choose Collapse Selected into Subnet.

Move one or more nodes inside a subnetwork

  1. Select the node(s) and choose Edit ▸ Cut.

  2. Go inside the subnetwork and choose Edit ▸ Paste.

Connect the subnet’s inputs to node inputs inside the subnet

  1. Go inside the subnet.

  2. The network view shows four pseudo-nodes which represent the subnet’s inputs. Connect the output of one of the pseudo-nodes to the input of one of the real nodes in the subnet.

Choose the subnet’s output

  • Set the display flag of the node you want to provide the subnet’s output.

Label the subnet’s inputs

  1. View the subnet’s parameters in the parameter editor and click the Subnet tab.

  2. Edit the Input # Label text fields to control the message that pops up when the user presses on the inputs.

Node comments

You can edit the “comment” string for any node. By default this text is only visible in the info window, but you can make the comment appear next to the node in the network editor. This is useful for networks that will be shared with other people, to let you explain the node’s function in more detail than the name alone can express. It can be especially useful in “demo” or “example” networks.

To...Do this

Edit a node’s comment field

  1. In the network editor, open the node’s info window.

  2. Click in the comment field in the info window to edit it.

Show a node’s comment next to the node in the network

  1. In the network editor, open the node’s info window.

  2. Turn on Show comment in network below the comment field.

Network background images

To...Do this

Add a background image

In the network editor, choose Add ▸ Background image, or click the Add background image button on the toolbar.

Edit background images

In the network editor, turn on Tools ▸ Edit background images.

  • Drag the image to move it, or drag the corners of an image to resize it.

  • Click an image to select it, and use the icons to delete, link, or adjust the image.

    Delete

    Delete this image.

    Link to node

    Drag from this icon to a node to keep the image positioned relative to the node.

    Brightness slider

    Drag the slider to make the image more or less faded.

  • When you're done editing images, turn off Tools ▸ Edit background images.

  1. In the network editor, turn on Tools ▸ Edit background images.

  2. Click the image to select it.

  3. Drag from the link icon to the node you want the image to follow.

  4. Turn off Tools ▸ Edit background images.

Now if you drag the node, the image will move with it.

Networks and parameters

Networks

  • Network editor

    How to create, move, copy, and edit nodes.

  • Network navigation

    How to move around the networks and move between networks.

  • Connecting (wiring) nodes

    How to connect nodes to each other to make them work together.

  • Network types and node flags

    Flags represent some state information on the node, such as which node represents the output of the network. Different network types have different flags.

  • Badges

    Badges indicate some status information about a node. They usually appear as a row of icons below the name of the node.

  • Node Info

    The node info window shows a quick overview of statistics and information about a particular node.

  • Find nodes in a network

    How to use the Find dialog to find nodes based on various criteria.

Editing parameters

Next steps

Expressions

Guru level

Reference