A question that comes up quite often is “Will Scene Nodes replace Xpresso?”, or a variation of it “Why can’t Scene Nodes do what Xpresso can?”.

The answer for both is the same, Scene Nodes and Xpresso do not work within the same context. They don’t solve the same kinds of problems and therefore one can not replace the other.

The name Xpresso comes from them being Expressions. Expressions are designed and engineered to control parameters, very similar to what Key Frame animations do. Basically everything that shows up in the Attribute Manager if you select an object can be controlled by them.

Scene Nodes on the other hand are designed to create and modify objects and geometry, something Xpresso simply can’t do. The capsules you build with Scene Nodes can have any number of Parameters, which then can be controlled by Xpresso, but that’s the closest the two can get.

The use of objects and tags in the object manager is an indicator of this divide. Xpresso lives firmly on the right side of it, as an addition to objects, controlling their functionality. Scene Node capsules live firmly on the left side of the object manager, where they create or modify objects.

The same difference in context exists when it comes to node based materials, they live in a different context again.

There is a gray area here and that is if you dive into the depth of Scene Nodes and work on the Scene root using the experimental Op nodes. In this specific context Scene Nodes reign supreme and can also control the parameters of objects, but only the experimental Op based objects of Scene Nodes. Here Scene Nodes can also control the parameters of node based materials.