Visual Linking			Expression Nodes
Chapter 24, Expressions

Topics on this Page:

Visual Linking in the Tool UI

Visual Linking in the Composition Browser

Visual Linking between the Composition Browser and the Tool UI

You can visually link attributes within the Tool UI, in the Composition Browser or between the Tool UI and the Composition Browser. However, visual linking of structured inputs can only be done through the Composition Browser.

Visual Linking in the Tool UI

The Tool UI displays editors (value editors, toggle buttons or menus) and labels. Visual linking relies on the attribute labels as zones to trigger a link gesture. Labels are already used for marking.

• Click the Red channel label, drag and drop on the Blue channel label.

  This sets an expression on the Blue channel attribute referring to the Red channel attribute without ever displaying the Expresso Calculator.

  

In the same way, you can link inputs belonging to separate groups, setting an expression in the target attribute referring to the source input.

Visual Linking in the Composition Browser

You can perform visual linking operations within the Composition Browser.

Linking simple inputs in the Composition Browser works like in the tool UI; you can click and drag attribute names (labels) to define a link expression. Simple inputs are defined as those inputs that have only one socket name.

Once the visual link has been established, the target attribute's value assumes that of the reference attribute. A green E then appears in the A column of the Composition Browser.

Linking structured inputs is done by dragging and dropping a structured input onto another. If the target structured input's topology doesn't match the source one, the drop is not accepted (i.e. the drop feedback is not given to you while dragging the pointer). The graphic below illustrates how an attribute with structured inputs (Master Gamma) can be visually linked with another attribute with structured attributes (Master Gain).

When the source and target structured inputs match (that is, when they have the same number of inputs) an expression per input is set, linking inputs individually.

Visual Linking between the Composition Browser and the Tool UI

You can initiate a drag from the Composition Browser and drop it on a label on the tool UI, linking the source and target attributes with an expression.