python : 偵測一個點是在某個模型內或外

有一位cgtalk 的網友寫了一個 python function, 使用 maya python API 來偵測一個點是在模型裡面或外面 (point inside object) . 這程式還沒經過加速改善,所以處理大量data可能會有點慢,可是一般來說應該還蠻好用的.

import maya.OpenMaya as OM
from math import fmod

def pyRayIntersect(mesh, point, direction=(0.0, 1.0, 0.0)):

  OM.MGlobal.selectByName(mesh,OM.MGlobal.kReplaceList)
  sList = OM.MSelectionList()
  #Assign current selection to the selection list object
  OM.MGlobal.getActiveSelectionList(sList)

  item = OM.MDagPath()
  sList.getDagPath(0, item)
  item.extendToShape()

  fnMesh = OM.MFnMesh(item)
  raySource = OM.MFloatPoint(point[0], point[1], point[2], 1.0)
  rayDir = OM.MFloatVector(direction[0], direction[1], direction[2])
  faceIds = None
  triIds = None
  idsSorted = False
  testBothDirections = False
  worldSpace = OM.MSpace.kWorld
  maxParam = 999999
  accelParams = None
  sortHits = True
  hitPoints = OM.MFloatPointArray()
  #hitRayParams = OM.MScriptUtil().asFloatPtr()
  hitRayParams = OM.MFloatArray()
  hitFaces = OM.MIntArray()
  hitTris = None
  hitBarys1 = None
  hitBarys2 = None
  tolerance = 0.0001
  hit = fnMesh.allIntersections(raySource, rayDir, faceIds, triIds, idsSorted, worldSpace, maxParam, testBothDirections, accelParams, sortHits, hitPoints, hitRayParams, hitFaces, hitTris, hitBarys1, hitBarys2, tolerance)

  result = int(fmod(len(hitFaces), 2))

  #clear selection as may cause problem if the function is called multiple times in succession
  #OM.MGlobal.clearSelectionList()
  return result

測試程式:

from pymel.core import *




def testIntersect():

  sel = ls(sl=1)




  container = sel[0]

  checkInsideObj = sel[1]  




  allVtx = ls(str(checkInsideObj)+'.vtx[*]',fl=1)

  allIn = []

  start = timerX()

  for eachVtx in allVtx:

      location = pointPosition(eachVtx,w=1)

      test = pyRayIntersect(container,location,(0,1,0))

      if(test):

          allIn.append(eachVtx)

   

  elapsedTime = timerX(startTime = start)



  print "time :",elapsedTime

  select(allIn,replace=1)