Make it dynamic

make_dynamic.py

from maya import cmds, mel
from contextlib import contextmanager
from mayakit.tags import tag, untag, query, search, message, unmessage, connect


@contextmanager
def selection(nodes=None):

    old_selection = cmds.ls(sl=True)
    try:
        if nodes is not None:
            cmds.select(nodes, replace=True)
        yield
    finally:
        cmds.select(old_selection)


@contextmanager
def undo_chunk():

    try:
        cmds.undoInfo(openChunk=True)
        yield
    finally:
        cmds.undoInfo(closeChunk=True)


def get_frame_range():
    slider = mel.eval("$pytmp=$gPlayBackSlider")
    frame_range = cmds.timeControl(slider, q=True, rangeArray=True)
    if frame_range == [1.0, 2.0]:
        frame_range = cmds.playbackOptions(q=True, minTime=True), cmds.playbackOptions(q=True, maxTime=True)
    return [int(frame_range[0]), int(frame_range[1])]


def make_dynamic(xform, weight=0.8):
    '''Make an xform dynamic'''

    message(xform, "nucleus")
    message(xform, "nParticle")
    message(xform, "nParticleXform")
    message(xform, "dyn_locator")

    # Create objects
    position = cmds.xform(xform, query=True, worldSpace=True, rotatePivot=True)
    parti, parti_shape = cmds.nParticle(position=position)
    cmds.setAttr(parti_shape + ".particleRenderType", 4)
    cmds.goal(parti_shape, useTransformAsGoal=True, weight=weight, goal=xform)
    nucleus = cmds.listConnections(parti_shape, type="nucleus")[0]
    dyn_locator = cmds.spaceLocator()[0]
    dyn_locator = cmds.rename(dyn_locator, xform + '_dyn')
    cmds.connectAttr(parti_shape + '.centroid', dyn_locator + '.t')

    connect("message", "nucleus", nucleus, xform)
    connect("message", "nParticle", parti_shape, xform)
    connect("message", "nParticleXform", parti, xform)
    connect("message", "dyn_locator", dyn_locator, xform)


def make_selected_dynamic(weight=0.8):

    xforms = cmds.ls(sl=True, transforms=True)
    for xform in xforms:
        make_dynamic(xform, weight=weight)


def bake_dynamic(xform):

    dyn_loc_attr = xform + '.dyn_locator'
    if not cmds.objExists(dyn_loc_attr):
        cmds.warning("xform has no dynamics.")
        return

    dyn_locator = cmds.listConnections(dyn_loc_attr)
    if not dyn_locator:
        cmds.warning("Xform is not attached to a dyn locator")
        return

    dyn_locator = dyn_locator[0]

    # Get Translate values from dyn_locator
    start_frame = int(cmds.playbackOptions(q=True, minTime=True))
    end_frame = int(cmds.playbackOptions(q=True, maxTime=True))
    frame_range = list(range(start_frame, end_frame))
    keys = []
    old_frame = cmds.currentTime(q=True)
    with undo_chunk():
        for frame in frame_range:
            cmds.currentTime(frame)
            keys.append(cmds.getAttr(dyn_locator + '.translate')[0])
    cmds.currentTime(old_frame)

    # Set keyframes on xform
    for frame, key in zip(frame_range, keys):
        cmds.setKeyframe(xform + '.tx', value=key[0], time=frame)
        cmds.setKeyframe(xform + '.ty', value=key[1], time=frame)
        cmds.setKeyframe(xform + '.tz', value=key[2], time=frame)

    nucleus = cmds.listConnections(xform + '.nucleus')[0]
    parti = cmds.listConnections(xform + '.nParticleXform')[0]
    parti_shape = cmds.listConnections(xform + '.nParticle')[0]

    cmds.delete([nucleus, parti, parti_shape, dyn_locator])


def bake_selected_dynamic():

    xforms = cmds.ls(sl=True, transforms=True)
    for xform in xforms:
        bake_dynamic(xform)


if __name__ == "__main__":
    print(get_frame_range())

    with undo_chunk():
        with selection():
            make_selected_dynamic(0.4)
        bake_selected_dynamic()