MoveInstanceInsertionPoint.py

import rhinoscriptsyntax  as rs
import scriptcontext as sc
import Rhino

def MoveBlockInsertionPoint():
    
    id = rs.GetObject("Select a block instance", 4096, preselect=True)
    if not id: return
    name = rs.BlockInstanceName(id)
    
    xform = rs.BlockInstanceXform(id).TryGetInverse()
    
    #check for linking
    if rs.BlockStatus(name) != -3 :
        print "Sorry, can't handle linked blocks..."
        return
    
    ids = rs.BlockInstances(name)

    obj = sc.doc.Objects.Find(id)
    
    pt = obj.InsertionPoint
    
    geo = obj.Geometry
    
    p2 = rs.GetPoint("Set new insertion point", pt)
    if not p2: return
    
    vecDir = pt-p2
    
    #Transform the vector by the instance (reverse) transform, 
    # i.e. back to the origin
    vecDir.Transform(xform[1])
    
    idef = obj.InstanceDefinition
    
    
    if idef:
        idx = idef.Index
        containers = idef.GetContainers()
        rhino_objects = idef.GetObjects()
        attrList = [rhino_objects[i].Attributes for i in range(len(rhino_objects))]
        geoList = []
        
        for r_obj in rhino_objects:
            #Move the definition geometry
            #by the vector
            r_obj.Geometry.Translate(vecDir)
            geoList.append(r_obj.Geometry)
    
            pass
    #Modify the definition
    sc.doc.InstanceDefinitions.ModifyGeometry(idx, geoList, attrList)
    
    rs.EnableRedraw(False)
   
    #modify instances that are contained in other instances.
    if containers:
            for container in containers:
                c_idx = container.Index
                c_objects = container.GetObjects()
                c_geoList = []
                c_attrList = []
                mod = False
                for c_obj in c_objects:
                    c_geoList.append(c_obj.Geometry)
                    c_attrList.append(c_obj.Attributes)
                    
                    if isinstance(c_obj, Rhino.DocObjects.InstanceObject):
                        if c_obj.InstanceDefinition.Name == name:
                            mod = True
                            vec = Rhino.Geometry.Vector3d(vecDir)
                            vec.Reverse()
                            vec.Transform(c_obj.InstanceXform)
                            c_obj.Geometry.Translate(vec)
                if mod:
                    sc.doc.InstanceDefinitions.ModifyGeometry(c_idx, c_geoList, c_attrList)
       
       #modify top level instances
    for i in range (len(ids)):
        #get new copy of the transformed-to-the-origin move vector
        vec = Rhino.Geometry.Vector3d(vecDir)
        vec.Reverse()
        
        #Get the instance transform,
        #Transform the reversed vector back to the instance
        vec.Transform(rs.BlockInstanceXform(ids[i]))
        
        #Move the instance
        rs.MoveObject(ids[i], vec)
            
    rs.EnableRedraw(True)


if __name__=='__main__':MoveBlockInsertionPoint()

Added check for linked and nesting - those are not handled.

Handles nested and transformed blocks, better at least. I do not see how it will be possible to do linked blocks.

Note: if this block is used in another block, the blocks using it will change this block's position within the parent block if this block's IP is moved. I do not see any easy way to avoid that - there might be a complicated way.

Now handles nesting this block in parent blocks correctly, I think.