Working with node connections

Once you add nodes to the Node Graph panel, you need to establish the connections between nodes to form a network. Most of the nodes have the Input, Output, and Mask connectors. These connectors determine the order in which the data stream is passed through the nodes. Figure 1 shows the connectors on the Blur1 node. Some nodes such as Merge has two input connectors: A and B. Figure-1 shows the connectors of a Merge node.

Figure 1 The Blur1 and Merge1 nodes

Disconnecting Nodes
To disconnect a node, press and hold the left mouse button on the head or tail of the connecting arrow and then drag the cursor to an empty area of the Node Graph panel. Alternatively, you can select the node and then press CTRL+D.

Reconnecting Nodes
To reconnect a node, press and hold the left mouse button on the head or tail of the connecting arrow of the node that you want to connect. Now, drag the cursor to the center of the node to which you need to make the connection and then release the left mouse button; a connection will be established between the two nodes. Alternatively, select the node (lower in the hierarchy) that you want to connect and then press and hold SHIFT. Next, select the node that you need to connect to and then press Y; a connection will be established between the two nodes.

Extracting Nodes
To extract the node, select the node that you need to extract from the node network and then choose Edit > Extract from the menu bar; the selected node will be extracted from the node network and will be placed as a free floating node in the Node Graph panel. Alternatively, you can press CTRL+SHIFT+X to extract the node. Figure 2 shows the Grade2 node extracted from the node network.

Figure 2 The extracted Grade2 node

Swapping Inputs of Nodes
Some nodes like Merge have two inputs: A and B. To swap the A input with the B input, make sure that the Merge node is selected in the Node Graph panel and then choose Edit > Node > Swap A - B from the menu bar. Alternatively, you can press SHIFT+X to swap the inputs. Figures 3 and 4 show the default and swapped inputs, respectively.

Figure 3 The default A and B inputs

Figure 4 The swapped inputs

Starting a New Branch from a Node

To create a new branch from a node, select the node from which you want to create a new branch. Next, press and hold SHIFT and then add new node using the Nodes toolbar, TAB menu, shortcut menu, or the shortcut key. Figure 5 shows two branches originating from the Blur3 node.

Figure 5  The branches originating from the Blur3 node

Duplicating the Connecting Arrow
To duplicate the connecting arrow, press and hold SHIFT and then drag the head of the output connecting arrow; a duplicate connection pipe will be displayed. Next, drop the pipe onto the node that you want to connect. This will duplicate the connecting arrow without affecting the original connection. Figure 6 shows a duplicate output arrow connected to the Grade2 node from the Blur2 node.

Figure 6  Duplicating a connecting arrow

This article is taken from the Nuke Book: The Foundry Nuke 7 for Compositors.