Hierarchical Transform

This page describes how to create objects with hiearchical transform using Verse. This is a standard feature of many 3D and VR systems, used to create a "scene graph" holding all the content of a scene. Verse is not designed as a scene graph from the ground up, although it is certainly possible to express that one object should be in the space of another, in a nested fashion.

In Verse, only object nodes can form hierarchical relationships. This means that all pure "content" nodes, like geometries, bitmaps, and materials, are always in a flat sort of space, with no spatial relationships to each other.

The "child" Link

The way to express that one object should be hierarchically "below" another, i.e. in its space, is to set a link from the parent to the child, and label the link "child". That is all you have to do to express the relationship.

The relevant section of the core spec has a bit more detail.

A VML Example

There is a standard VML example of hierarchical transform, in the vml CVS module.

Above is an edited screenshot of Connector, showing the node graph for the hierarchical car VML, mentioned above. The child links go from the toplevel "body" object of the car, to four objects that represent each of the wheels. They are marked with an orange ellipse in the image. The reason there are two different geometries for the tires is that they are not symmetrical. Left and right versions exist, to make the transformations simpler.