如何修复'TypeError：在方法'MFnMesh_anyIntersection'中，Maya中Python中'MINtArray const *'类型的参数4错误

Question

我想用 Python 在 Maya 中使用 OpenMaya.MFnMesh.anyIntersection() 尝试一些光线投射。

我只想从物体上向下投射光线并击中飞机，而不是进一步，所以我只得到一个 raycasthit 并从 raycasthit 中获取平移值。

我从视频中得到了代码，并使其更清晰易懂。

为了使代码在 Maya 中正常运行，您需要一个在 Y 轴上高于其他对象的对象，最好是 polyPlane（例如：在位置 [0, 3, 0] 有一个 polySphere 和一个 polyPlane在 [0, 0, 0] 位置，选择 polySphere 并运行代码）

import maya.OpenMaya as OpenMaya
import maya.cmds as cmds

def RayReposition(*args):
    direction = (0.0, -1, 0)
    sel = cmds.ls(sl = True)

    fromPositionRay = cmds.xform(sel[0], query = True, translation = True)
    selShape = cmds.listRelatives(shapes = True)
    meshes = cmds.ls(geometry = True)

    cmds.select(clear = True)

    for x in meshes:
        if x == selShape[0]:
            continue
        else:
            OpenMaya.MGlobal.selectByName(x)
            sList = OpenMaya.MSelectionList()

            OpenMaya.MGlobal.getActiveSelectionList(sList)
            item = OpenMaya.MDagPath()
            sList.getDagPath(0, item)
            item.extendToShape()

            fnMesh = OpenMaya.MFnMesh(item)

            raySource = OpenMaya.MFloatPoint(fromPositionRay[0], fromPositionRay[1], fromPositionRay[2], 1.0)
            rayDir = OpenMaya.MFloatVector(direction[0], direction[1], direction[2])
            faceIds = None
            triIds = None
            idsSorted = False
            testBothDirections = False
            worldSpace = OpenMaya.MSpace.kWorld
            maxParam = 999999
            accelParams = None
            sortHits = True
            hitPoints = OpenMaya.MFloatPointArray()

            hitRayParams = OpenMaya.MFloatArray()
            hitFaces = OpenMaya.MIntArray()
            hitTris = None
            hitBarys1 = None
            hitBarys2 = None
            tolerance = 0.0001

            hit = fnMesh.anyIntersection(raySource, rayDir, worldSpace, maxParam, testBothDirections, faceIds, triIds, idsSorted, accelParams, tolerance, hitPoints, hitRayParams, hitFaces, hitTris, hitBarys1, hitBarys2)

            OpenMaya.MGlobal.clearSelectionList()
            firstHit = (hitPoints[0].x, hitPoints[0].y, hitPoints[0].z)
            print firstHit

RayReposition()

我希望从 raycasthit 中获取翻译值，但我收到以下错误：

TypeError: in method 'MFnMesh_anyIntersection', argument 4 of type 'MIntArray const *'

使用 OpenMaya.MFnMesh.allIntersections() 函数可以正常工作，但我从光线投射中获得了每一次命中，但我只想要 first 命中。

OpenMaya.MFnMesh API 的链接： 链接：https://help.autodesk.com/view/MAYAUL/2016/ENU/?guid=__py_ref_class_open_maya_1_1_m_fn_mesh_html

Answer 1

主要是anyIntersection 正在寻找它首先命中的单个 交叉点，而不是多个交叉点。所以你的输出参数是错误的类型，因为它们是数组。

我也会避免在循环中清除或做出新的选择，因为每次都必须重新绘制视口会降低性能。

这是一个工作示例，它将在它命中的第一个网格上创建一个定位器：

import maya.OpenMaya as OpenMaya
import maya.cmds as cmds


def RayReposition(*args):
    direction = (0.0, -1, 0)
    sel = cmds.ls(sl=True)

    fromPositionRay = cmds.xform(sel[0], query=True, translation=True)
    selShape = cmds.listRelatives(shapes=True)
    meshes = cmds.ls(geometry=True)

    for x in meshes:
        if x == selShape[0]:
            continue
        else:
            sList = OpenMaya.MSelectionList()
            sList.add(x)
            item = OpenMaya.MDagPath()
            sList.getDagPath(0, item)
            item.extendToShape()

            fnMesh = OpenMaya.MFnMesh(item)

            raySource = OpenMaya.MFloatPoint(fromPositionRay[0], fromPositionRay[1], fromPositionRay[2], 1.0)
            rayDir = OpenMaya.MFloatVector(direction[0], direction[1], direction[2])
            worldSpace = OpenMaya.MSpace.kWorld
            maxParam = 999999
            testBothDirections = False
            faceIds = None
            triIds = None
            idsSorted = False
            accelParams = None
            sortHits = True

            hitPoints = OpenMaya.MFloatPoint()
            hitRayParams = None
            hitFaces = None
            hitTris = None
            hitBarys1 = None
            hitBarys2 = None
            tolerance = 0.0001

            hit = fnMesh.anyIntersection(
                raySource, rayDir, faceIds, triIds, idsSorted, worldSpace, maxParam, testBothDirections, accelParams, 
                hitPoints, hitRayParams, hitFaces, hitTris, hitBarys1, hitBarys2, tolerance)

            if hit:
                firstHit = (hitPoints.x, hitPoints.y, hitPoints.z)
                loc = cmds.spaceLocator()[0]
                cmds.xform(loc, ws=True, t=firstHit)
                print "Hit on {} at {}".format(x, firstHit)
                break


RayReposition()

我发现c++ documentation 更清楚该方法对参数的期望。