Working with the Scene Graph

The scene graph is a tree of scene nodes. Each node is a hub of information for objects in the scene, and is responsible for:

• applying modifiers to an object
• storing information about the geometry
• storing information about shading materials
• storing position, rotation, and scale information
• storing node tree hierarchical information: the parent and child of the node

Traversing the Scene Graph

The root node of a scene can be accessed by the MAXScript rootNode global. See, for example, the scene_graph.py sample script:

'''
    Creates a simple text representation of the scene graph
'''
from pymxs import runtime as rt 

def output_node(node, indent=''):
    """Print the scene graph as text to stdout."""
    print(indent, node.Name)
    for child in node.Children:
        output_node(child, indent + '--')

output_node(rt.rootnode)

Getting Scene Objects

If you do not need the scene hierarchy information (that is, parent/child relationships), you can get a flat list of all objects in the scene with the objects global variable. For example:

objs = pymxs.runtime.objects
for o in objs:
    print(o.name)

You can also obtain individual objects by name:

s = pymxs.runtime.getNodeByName('Sphere002')

Finally, you can also access objects by PathName values, though this is not directly exposed to pymxs and requires a work-around. See Accessing MAXScript PathName Values for more information.

Getting the Selection List

There are times when it is useful to get the list of selected objects in a scene.

There are several reserved system variables of type ObjectSet that contain various scene object categories. For example, objects contains all the objects in the scene, lights all the lights, and selection contains the current selection.

For example:

>>> pymxs.runtime.selection
<ObjectSet<$selection>>
>>> pymxs.runtime.selection[0]
<Sphere<$Sphere:Sphere004 @ [90.515228,15.940669,0.000000]>>
>>>

Named selection sets are contained in the selectionSets array, and are accessed by index.

for example:

>>> pymxs.runtime.selectionSets[0]
<SelectionSet<SelectionSet:my_selection>>