Modo Python API example for skin weight access

cmdPrintWeights.py

# Python API example for skin weight access
# Place this file into an lxserv folder
#
# Creates a command that takes the names of a mesh and a connected joint locator and inverts the weight values
#
# Example command usage:
#   example.printJointWeights locator:"Skeleton_Joint (4)" mesh:MyCube

import lx
import lxu
import lxifc


def printJointWeights(jointLocatorName, meshName):

    scn_svc = lx.service.Scene()

    # Get the scene and the two items by name
    scene = lxu.select.SceneSelection().current()
    mesh_item = scene.ItemLookup(meshName)
    locator_item = scene.ItemLookup(jointLocatorName)

    # Set the mesh up
    channelWrite = lx.object.ChannelWrite(scene.Channels(lx.symbol.s_ACTIONLAYER_SETUP, 0.0))
    channelRead = lx.object.ChannelRead(scene.Channels(None, 0.0))
    write_mesh_obj = channelWrite.ValueObj(mesh_item, mesh_item.ChannelLookup(lx.symbol.sICHAN_MESH_MESH))
    mesh = lx.object.Mesh(write_mesh_obj)

    # We want to find the connected influence deformer using the 'deformers' graph
    graph = lx.object.ItemGraph(scene.GraphLookup('deformers'))
    desired_type = scn_svc.ItemTypeLookup('genInfluence')

    # In the simplest case we can assume that the first found deformer is the influence
    deformer = graph.FwdByIndex(locator_item, 0)

    # We need the internal name of the weight map to look it up using the meshmap accessor below
    mapname = lx.object.WeightMapDeformerItem(deformer).GetMapName(channelWrite)
    ui_name = deformer.UniqueName()

    lx.out('-' * 80)
    lx.out(ui_name)
    lx.out(mapname)

    # Set up a storage buffer to read the value into
    storageBuffer = lx.object.storage('f', 1)

    # Loop through all points
    for index in range(mesh.PointCount()):

        # Create a point- and meshmap accessor respectively and select the relevant component
        point_accessor = mesh.PointAccessor()
        point_accessor.SelectByIndex(index)

        meshmap_accessor = mesh.MeshMapAccessor()
        meshmap_accessor.SelectByName(lx.symbol.i_VMAP_WEIGHT, mapname)

        # Read and print the value
        if point_accessor.MapEvaluate(meshmap_accessor.ID(), storageBuffer):
            value = storageBuffer.get()
            lx.out(index, value)

            # Write the inverted value back
            storageBuffer.set((1.0 - value[0],))
            point_accessor.SetMapValue(meshmap_accessor.ID(), storageBuffer)

    # Update the mesh
    mesh.SetMeshEdits(lx.symbol.f_MESHEDIT_MAP_OTHER)


class CmdPrintJointWeights(lxu.command.BasicCommand):
    def __init__(self):
        lxu.command.BasicCommand.__init__(self)

        # Add two string arguments
        self.dyna_Add('locator', lx.symbol.sTYPE_STRING)
        self.dyna_Add('mesh', lx.symbol.sTYPE_STRING)

    def cmd_Flags(self):
        return lx.symbol.fCMD_MODEL | lx.symbol.fCMD_UNDO

    def basic_Enable(self, msg):
        return True

    def cmd_Interact(self):
        pass

    def basic_Execute(self, msg, flags):
        if self.dyna_IsSet(0) and self.dyna_IsSet(1):

            locatorName = self.dyna_String(0, None)
            meshName = self.dyna_String(1, None)

            printJointWeights(locatorName, meshName)

    def cmd_Query(self, index, vaQuery):
        lx.notimpl()


lx.bless(CmdPrintJointWeights, "example.printJointWeights")