Wow, definitely seems worth investigating. Thanks for the code snippet and
timing info!
On Sunday, August 5, 2012, Justin Israel wrote:
> As a random example...I created a nurbsSphere, and just simulated looping
> over 5000 objects and setting and attrib.
>
> import maya.OpenMaya as om
> import time
> import maya.cmds as cmds
>
> sel = om.MSelectionList()
> om.MGlobal.getActiveSelectionList(sel)
> iter = om.MItSelectionList(sel)
>
> obj = om.MObject()
> depFn = om.MFnDependencyNode()
>
> start = time.time()
> for i in xrange(5000):
> iter.getDependNode(obj)
> depFn.setObject(obj)
> depFn.findPlug("tx").setInt(4)
> end = time.time()-start
> print end
> # 0.0979061126709 seconds
>
> start = time.time()
> for i in xrange(5000):
> name = "nurbsSphere1"
> cmds.setAttr("{0}.tx".format(name), 4)
> end = time.time()-start
> print end
> # 0.261173009872 seconds
>
>
>
>
> On Aug 4, 2012, at 12:22 PM, Justin Israel wrote:
>
> Some of the big speed increases are using the iterators and not having to
> do a bunch of string operations on dag paths. And the math speedups from
> using the OpenMaya objects with operators.
>
> Your best bet it to just profile some small tests. You can easily make use
> of the python `timeit` module to check the difference in speed of
> operations.
>
>
>
> On Aug 4, 2012, at 10:53 AM, matt wrote:
>
> Apologies for the crosspost for anyone on maya_he3d, only remembered this
> group existed seconds after I posted over there... Have tried to edit and
> re-word for you smart people. :)
>
> Short version:
> Would using the python OpenMaya module give big speed gains for selecting
> thousands of objects and modifying their attributes?
>
> Long version:
> We have a python based, text based render pass submission tool for
> lighters at work. One of its core functions is grabbing whatever geometry
> is defined by a lighter, and setting attributes. This sometimes means
> adding attributes first (or connecting our custom attribute node), then
> setting
> them.
>
> We're getting into the situation where we have _very_ heavy scenes, with
> thousands of objects. Normally our system will process these scenes within
> a minute or two per frame, if lighters use wildcards, eg 'set:tree*',
> that can jump to maybe 6 mins per frame. Not too bad.
>
> Things get messy with our alembic style heirachical geo format. It can
> contain many sub-objects, which our maya plugin doesn't allow us to list or
> search for sub-objects names easily. Thus, if a lighter wildcards to the
> sub-object level, eg "set:*|leaves*", the only safe way to do that is to
> process every object, then every sub-object, unsetting atts those objects
> which AREN'T leaves, and setting attrs on those objects which ARE leaves.
> When this happens, processing jumps to 3 hours per frame. Yuck!
>
> In the short term we're getting lighters to be more careful with
> wildcards, in the mid term getting assets collapsed down so they're not so
> name and sub-object heavy, and in the long term getting our geo plugin more
> inspectable. So that's good.
>
> I was curious though.... could this be helped in the short(ish) term by
> re-writing that part of the code with the OpenMaya module? I recall
> reading there's many things which are faster, a few which are slower, and
> fewer still which have no OpenMaya equivalent and can only be done in
> mel/python. I have a sneaking suspicion one of those slow things was
> something fundamental like selection, but I'm hoping I'm wrong.
>
> Was curious if the basic idea of 'yeah, manipulating hundreds of objects
> and their attributes is N times faster with OpenMaya' is worth pursuing.
>
> -matt
>
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