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Wrapping a cask object from a PyAlembic IObject without creating a cask.Archive first can cause reference errors, e.g.

>>> iarch = alembic.Abc.IArchive(filepath)
>>> iobj = iarch.getTop().children[0]
>>> obj = cask.Xform(iobj)
>>> obj.is_animated()
...
    return self.parent.time_sampling_id
ReferenceError: weakly-referenced object no longer exists

This is because cask walks to the top to get the time smapling information, and the iarchive doesn't exist, or is weakly referenced.

A temporary fix is to pass in the time sampling id when instantiation the object, e.g.

>>> obj = cask.Xform(iobj, time_sampling_id=2)

A better fix might be to instantiate the archive on demand, or create a strong reference to the archive, if possible. I'm labeling this as an enhancement because this is an unexpected workflow in cask, but it'd be good to support.

Hello and thanks for cask.

I try to generate an abc file from scrach.

It’s supposed to represent a Root/particleShape node of type Points (with two points in my example).

import alembic
import cask
import imath

b = cask.Archive()
root = cask.Xform(name='Root')
root.parent = b.top

assert b.top.children['Root']

pts = cask.Points(name='particleShape')
pts.parent = root

assert root.children['particleShape']
assert b.top.children['Root/particleShape']

point_count = 2

id_array = imath.IntArray(point_count)
id_array[0] = 0
id_array[1] = 1

pos_array = imath.V3fArray(point_count)
pos_array[0] = imath.V3f(0.0, 0.0, 0.0)
pos_array[1] = imath.V3f(10.0, 0.0, 0.0)

# uncomment to fix
# cask.Points._sample_class = alembic.AbcGeom.OPointsSchemaSample

pts_sample = alembic.AbcGeom.OPointsSchemaSample()
pts_sample.setIds(id_array)
pts_sample.setPositions(pos_array)

pts.set_sample(pts_sample)

b.write_to_file("test.abc")

This code raise an assert :

Traceback (most recent call last):
  File "/code.py", line 138, in <module>
    pts.set_sample(pts_sample)
  File "/cask.py", line 1434, in set_sample
    "Can not set %s on %s object" % (sample.__class__.__name__, self.type())
AssertionError: Can not set OPointsSchemaSample on Points object

After some digging into cask code, I thing there is missing _sample_class property , from Points class : https://github.com/alembic/cask/blob/master/cask.py#L1684

Maybe it’s a bug, maybe there is good reason for this (don’t hesitate to justified in tho Points class docstring).

Adding the property (uncomment the line) seems to work. I say seems as abcls prints the same output between my fresh abc and my reference one.

What are you thought about this ?

Thanks in advance !

Hi,

I'm trying to add properties under .geom/.arbGeomParams on an Archive i create from scratch, but it seems that my properties do not get saved. Also, if i query the properties of my object I get an empty list.

Is this supported at all ?

Thanks !

This link in the readme is broken:

http://docs.alembic.io/python/cask.html

I am having a problem that issue #23 should resolve: not preserving properties. This error is occurring in cask version 1.0.2. I would like to know if the version I am on has the fix for issue #23. I didn't see any info on this issue, so logging to confirm.

Thanks!

I have been able to compile PyAlembic for Python 3.7 on Linux and have a Python 3.7 testing environment.

We are slowly moving our tools to Python 3 and one of them use alembic/cask to generate Alembic file from scratch.

My proposition is that I do it myself and submit a PR. The plan is that cask would be Python 2/3 compatible. I will try to rely on builtins:

from __future__ import (absolute_import,
                        division,
                        print_function,
                        unicode_literals)

And nothing more do don't add new dependencies (no six or future).

Is there any interest in this? Are you already working on it?

Thanks in advance!

i've been trying to use cask to merge two alembic files that contain only materials in.

def run(fileA, fileB, fileOut):
	a = cask.Archive(fileA)
	b = cask.Archive(fileB)
	
	o = cask.Archive()
	o.top.children["materials"] = cask.Material()

	for i in a.top.children['materials'].children:
		o.top.children['materials'].children[i] = a.top.children['materials'].children[i]

	for i in b.top.children['materials'].children:
		o.top.children['materials'].children[i] = b.top.children['materials'].children[i]

	o.write_to_file(fileOut)

when executing this, it errors with:

Error setting value on .terminals: <imath.StringArray object at 0x23143d0> <class 'alembic.Abc.OArrayProperty'>
No registered converter was able to produce a C++ rvalue of type std::tr1::shared_ptr<Alembic::Abc::v7::TypedArraySampleAlembic::Abc::v7::StringTPTraits > from this Python object of type StringArray
Error setting value on aov_names: <imath.StringArray object at 0x2393ec0> <class 'alembic.Abc.OArrayProperty'>
No registered converter was able to produce a C++ rvalue of type std::tr1::shared_ptr<Alembic::Abc::v7::TypedArraySampleAlembic::Abc::v7::StringTPTraits > from this Python object of type StringArray
Error setting value on .connections: <imath.StringArray object at 0x2390130> <class 'alembic.Abc.OArrayProperty'>
No registered converter was able to produce a C++ rvalue of type std::tr1::shared_ptr<Alembic::Abc::v7::TypedArraySampleAlembic::Abc::v7::StringTPTraits > from this Python object of type StringArray
Error setting value on .interface: <imath.StringArray object at 0x2390130> <class 'alembic.Abc.OArrayProperty'>
No registered converter was able to produce a C++ rvalue of type std::tr1::shared_ptr<Alembic::Abc::v7::TypedArraySampleAlembic::Abc::v7::StringTPTraits > from this Python object of type StringArray
Error setting value on .terminals: <imath.StringArray object at 0x2390130> <class 'alembic.Abc.OArrayProperty'>
No registered converter was able to produce a C++ rvalue of type std::tr1::shared_ptr<Alembic::Abc::v7::TypedArraySampleAlembic::Abc::v7::StringTPTraits > from this Python object of type StringArray
Error setting value on aov_names: <imath.StringArray object at 0x2398d00> <class 'alembic.Abc.OArrayProperty'>
No registered converter was able to produce a C++ rvalue of type std::tr1::shared_ptr<Alembic::Abc::v7::TypedArraySampleAlembic::Abc::v7::StringTPTraits > from this Python object of type StringArray
Error setting value on .connections: <imath.StringArray object at 0x2398f30> <class 'alembic.Abc.OArrayProperty'>
No registered converter was able to produce a C++ rvalue of type std::tr1::shared_ptr<Alembic::Abc::v7::TypedArraySampleAlembic::Abc::v7::StringTPTraits > from this Python object of type StringArray
Error setting value on .interface: <imath.StringArray object at 0x7f596a88c280> <class 'alembic.Abc.OArrayProperty'>
No registered converter was able to produce a C++ rvalue of type std::tr1::shared_ptr<Alembic::Abc::v7::TypedArraySampleAlembic::Abc::v7::StringTPTraits > from this Python object of type StringArray

further down the line, when i try to use the merged file, arnold errors with:

Invalid sample index: -1, should be between 0 and 4294967295

im using alembic 1.5.8 and the default branch of cask.

any ideas how i can resolve these errors?

many thanks,

elliott

We're (me and @mdecaria) playing round with cask at the office right now, and I noticed what looks like an edge case in get_sample, which seems to be from __get_sample_index under the hood.

Basically, the default Archive constructor sets an fps of (int) 24 which is used as the divisor in __get_sample_index, so the getNearIndex call will be fed steppy numbers from the integer division.

Not sure if it's just us or the function is working as intended (the simple fix was to set the archive fps to 24.0) so I've thrown in a bit of a trivial PR for it since it looks like the rest of functions that rely on archive.fps have a float wrapper

Hi again !

Here's an example :
`
import cask

arch = cask.Archive(fps=24)
arch.set_start_frame(14)

arch.write_to_file("D:/TestTS.abc")

saved = cask.Archive("D:/TestTS.abc")
print saved.start_frame()
print saved.end_frame()
`

Running this, in my case, makes and Archive that starts at frame 14, but ends at frame 13. The archive is invalid, it will crash Maya and AbcEcho. Any ideas ?