MaxPlus Select by Volume

I was wandering around as usual when I stumbled across a post in Tech-Artists.org regarding a Maxscript question on how to select objects based on a volume. As usual some really smart guys got their hands dirty and solved the question using MXS.

But one of those answers was an example on how to do it in Maya and Python…. well I could not resist to that of course! We now have Python too! So I took a “minute” and converted that code into its MaxPlus counterpart.

All credit for the original Maya function goes of course to Eric Spevacek and you can check his original post here: http://technicallyitsart.wordpress.com/2013/12/28/maya-python-select-by-volume/

I’ve updated the YCDIVFX MaxPlus Packages in github, there is now a new package called maxhelpers where I will put code that will be reused across all other packages. I’ve also included a file in the MyExamples folder with the intended usage. Cheerios!

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Here’s the code and it’s usage:

"""
Based on the work of Eric Spevacek for Maya
http://technicallyitsart.wordpress.com/2013/12/28/maya-python-select-by-volume/
"""
import MaxPlus
import maxhelpers as mh

class BoundingBox():
    """ Helper class for bounding box-related calculations."""
    @classmethod
    def FromShape(cls, shapeObj):
        """ Constructor method to create a bounding box from a shape.
            :param MaxPlus.INode shapeObj: Node to extract bounding box
        """
        boundingBox = BoundingBox()
        bb = mh.GetWorldBoundBox(shapeObj)
        boundingBox.minX = bb.Min.X
        boundingBox.minY = bb.Min.Y
        boundingBox.minZ = bb.Min.Z
        boundingBox.maxX = bb.Max.X
        boundingBox.maxY = bb.Max.Y
        boundingBox.maxZ = bb.Max.Z
        return boundingBox

    def ContainsShape(self, shape):
        """ Returns whether or not a shape is intersecting with this bounding box.
        """
        shapeBB = BoundingBox.FromShape(shape)
        return (shapeBB.minX < self.maxX and shapeBB.maxX > self.minX) and 
               (shapeBB.minY < self.maxY and shapeBB.maxY > self.minY) and
               (shapeBB.maxZ < self.maxZ and shapeBB.maxZ > self.minZ)

def SelectByVolume(volumeObj):
    """ Selects all transforms in the scene that are within the specified argument's bounding box volume. """

    # Create bounding box class from object
    boundingBox = BoundingBox.FromShape(volumeObj)

    # Get all scene objects asides from bounding box
    sceneObjs = [obj for obj in MaxPlus.Core.GetRootNode().Children
                 if obj != volumeObj]

    # Compare against every object in our scene to determine what is in our volume
    newSelection = MaxPlus.INodeTab()
    for obj in sceneObjs:
        # If the shape's bounding box intersects with the volume's bounding box
        if boundingBox.ContainsShape(obj):
            newSelection.Append(obj)

    # Update selection to nodes contained in volume
    if newSelection:
        MaxPlus.SelectionManager.ClearNodeSelection()
        MaxPlus.SelectionManager.SelectNodes(newSelection)

import MaxPlus
from maxhelpers import BoundingBox

# Grab selected object to use as volume
obj = MaxPlus.SelectionManager.GetNode(0)

if obj:
    BoundingBox.SelectByVolume(obj)
else:
    print 'Select an object!'