align_to_grid.py

# Script Name: align_to_grid
#
# Author: Hyuk Ko | [email protected] | 2018.10.14
#
# Usage: 1.Select at least 3 vertices(or locators) which resembles the ground plane.
#        2.Run Script
#        3.Click on the 'N-gon' mesh (You should see a blue arrow)
#        4.Click on the 'ground plane' mesh (You should see a blue arrow)
#        5.Hit 'Enter'

import maya.cmds as mc
import pymel.core as pm
import maya.OpenMaya as om

def cleanUp():
    mc.select(clear=True)
    mc.isolateSelect(panelWithFocus, state=False)
    mc.delete(pc, newMeshTrans, tempPlaneTrans)
    
def getDagPath(nodeName):
    selList = om.MSelectionList()
    selList.add(nodeName)
    dagPath = om.MDagPath()
    selList.getDagPath(0, dagPath)
    return dagPath

# Turn on trackSelectionOrder
if mc.selectPref(q=True, trackSelectionOrder=True) is False:
    mc.selectPref(trackSelectionOrder=True)

selList = mc.ls(orderedSelection=True, flatten=True, long=True)
selListSize = len(selList)

if selListSize > 2:
    # Get Top Level Dag Object of selected vertex(or locator)
    try:
        rootPN = pm.PyNode(selList[0].split('.')[0])
    except:
        rootPN = pm.PyNode(selList[0])
    rootTrans = rootPN.root().longName()
    
    numPolygons = 1
    numVertices = selListSize
    
    selPosList = []
    for sel in selList:
        pos = mc.pointPosition(sel)
        selPosList.append(pos)
        
    vertexArray= om.MFloatPointArray()
    for selPos in selPosList:
        vertexArray.append(om.MFloatPoint(selPos[0], selPos[1], selPos[2]))
    
    polygonCounts = om.MIntArray()
    polygonCounts.append(numVertices)
    
    polygonConnects = om.MIntArray()
    for sel in selList:
        polygonConnects.append(selList.index(sel))
        
    parentM = om.MObject()
    newMesh = om.MFnMesh()
    newTransformOrShape = newMesh.create(numVertices, numPolygons, vertexArray, polygonCounts, polygonConnects, parentM)
    newMesh.updateSurface()
    
    dagpath = om.MDagPath()
    om.MDagPath.getAPathTo(newTransformOrShape, dagpath)
    
    newMeshPN = pm.PyNode(dagpath.fullPathName())
    newMeshTrans = newMeshPN.longName()
    
    mc.sets(newMeshTrans, edit=True, forceElement="initialShadingGroup")
    
    # If the normal is facing Y-up do Reverse
    if newMeshPN.faces[0].getNormal('world').y > 0.0:
        mc.polyNormal(newMeshTrans, normalMode=0, userNormalMode=0, ch=True)
    
    # Create Temp Plane
    tempPlaneTrans = mc.polyPlane(name='tempPlane#', w=1000, h=1000, sx=1, sy=1, ax=[0,1,0], ch=True)[0]
    
    # Parent Constraint 'newMesh(Parent)' to 'rootTrans(Child)'
    pc = mc.parentConstraint(newMeshTrans, rootTrans, mo=True)
    
    # Isolate 'newMesh' and 'tempPlane'
    panelWithFocus = 'modelPanel4' #mc.getPanel(withFocus=True)
    mc.select(newMeshTrans, tempPlaneTrans, replace=True)
    mc.editor(panelWithFocus, edit=True, lockMainConnection=True, mainListConnection='activeList')
    mc.isolateSelect(panelWithFocus, state=True)
    
    # Activate Snap Together Tool
    mc.setToolTo('snapTogetherToolCtx')
    
    # If Enter is Pressed, Disable Isolate Mode / Delete tempPlane / Delete newMesh
    job = mc.scriptJob(e=('PostToolChanged', cleanUp), runOnce=True)
    
else:
    mc.warning('Select at least 3 vertices(or locators)!')