This little project aims to create a random set of cones that “look at” a shiny red sphere passing by. The reference below shows the original maya + python youtube tutorial. The code that follows was saved as 2 shelf tools which can be used with any mesh.

The first script (randomInstances.py) creates 30 instances of the first object selected in the scene. These instances are then randomly positioned, rotated and scaled.

#randomInstances.py
import maya.cmds as cmds
import random
random.seed(1234)
result = cmds.ls(orderedSelection = True)
print 'result: %s ' %(result)
transformName = result[0]
instanceGroupName = cmds.group(empty = True, name = transformName + '_instance_grp#')
for i in range(0, 30):
   instanceResult = cmds.instance(transformName, name = transformName + '_instance#')
   cmds.parent(instanceResult, instanceGroupName)
   tx = random.uniform(-10, 10)
   ty = random.uniform(0, 20)
   tz = random.uniform(-10, 10)
   rotX = random.uniform(0, 360)
   rotY = random.uniform(0, 360)
   rotZ = random.uniform(0, 360)
   sXYZ = random.uniform(0.1, 1.25)
   cmds.move(tx, ty, tz, instanceResult)
   cmds.rotate(rotX, rotY, rotZ, instanceResult)
   cmds.scale(sXYZ, sXYZ, sXYZ, instanceResult)
cmds.hide(transformName)
cmds.xform(instanceGroupName, centerPivots = True)

The second script(aimAtFirst.py) takes the first elements selected and sets it as a target, while the rest of the elements selected are set as sources, looking at this target along their Y axis. At least one source and one target must be selected in order for the algorithm to work.

#aimAtFirst.py

selectionList = cmds.ls(orderedSelection = True)
if len(selectionList) >= 2:
   print 'Selected items: %s ' % (selectionList)
   targetName = selectionList[0]
   selectionList.remove(targetName)
   for objectName in selectionList:
      print 'Constraining %s towards %s ' %(objectName, targetName)
      cmds.aimConstraint(targetName, objectName, aimVector = [0, 1, 0])
else:
   print 'Please select 2 or more objects'

Reference: Autodesk Scripting on Youtube