3.2. Nodes are your building blocks

Each composition does something unique, and the way that you build up that something is by putting together nodes. These are your building blocks.

Let’s say you’re creating a composition that displays a 3D model. You might use the Fetch Scene node to load the 3D model from a file and the Render Scene to Window node to render the model in a window.

A node in Vuo is like a patch in Quartz Composer.

A node is like a function. It encapsulates a task. It takes inputs and produces outputs. More precisely, nodes are like class instance methods, since they can also maintain a state.

Or suppose you’re creating a composition that applies a color effect to a movie. You might use the Play Movie node to bring the movie into the composition, the Adjust Image Colors node to change the movie’s color, and the Save to Movie node to save the color-changed movie to a file.

Part of the process of creating a composition is taking your idea of what it should do and breaking that down into smaller tasks, where each task is carried out by a node. Each node in Vuo has a specific job that it does. Some nodes do simple jobs, like adding numbers or checking if two pieces of text are the same. Other nodes do something complex, like receiving a stream of video from a camera, finding a barcode in an image, or turning a 3D object into a wiggly blob. You can browse through a list of all the nodes available in the Node Library (the panel along the left side of the Vuo Editor window) or the online node documentation.

When you start making a composition, often the first thing you’ll do is pick a node from the Node Library. You can search the Node Library for what you want to do (for example, a search for movie brings up a list of nodes for playing, inspecting, and saving movies) and then drag the nodes you want onto the composition canvas.

You can learn about a node by looking at its title, node class name, and port names, which are pointed out in the illustration below. For a detailed description of how the node works, you can look at the node’s documentation, which appears in the Node Documentation Panel in the lower part of the Node Library. Many nodes come with example compositions (listed in the node’s documentation) that demonstrate the node in action.