Write Houdini attributes and groups via Pyton API

[Paul Winex]

I try to export Maya geometry using default maya python alembic package (Maya 2016). How should I write the attributes and groups that Houdini can to see them?

This is a simple exporter polygons. I need to add write custom attributes to abc
https://gist.github.com/paulwinex/421cf838c0d2def9a55f

Thanks!

[Lucas Miller]

You can either put it in user attributes, if it's pipeline specific attrs:
http://docs.alembic.io/python/examples.html#write-non-standard-data-for-a-polymesh

Or add them as arbitrary geometry parameters: (oschema.getArbGeomParams())

Lucas

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[Paul Winex]

I was tried this. Houdini cant see my data. https://gist.github.com/paulwinex/511974828d492e18b0c6  line 124

Can you get me any example witn oschema.getArbGeomParams()? Just simple example that write custom attribute (point ar prim) for houdini.

[Lucas Miller]

I can get you part way:

arb = mesh.getArbGeomParams()
mass = alembic.AbcGeom.ODoubleGeomParam(arb, "mass", False,
alembic.AbcGeom.GeometryScope.kVertexScope, 1)

I couldn't find a simple way to set samples on it though.

There are some more complicated hints in here though:

https://github.com/alembic/alembic/tree/master/python/PyAlembic/Tests

[Paul Winex]

Error evaluate file in Houdini with your example (((
I try to read file saved in Houdini to explore the structure. I use this code. http://derangedartisan.blogspot.ru/2014/04/testing-uv-export.html
But maya is crach on line 6.
Also i found getArbGeomParams in file testPolyMesh.py in tis examples https://github.com/alembic/alembic/tree/master/python/PyAlembic/Tests
But only two lines:
    arbattrs = mesh.getArbGeomParams()
    assert not arbattrs
"arbattrs" do not use more

пятница, 13 ноября 2015 г., 1:33:39 UTC+4 пользователь Lucas написал:

[Lucas Miller]

Yes, I didn't actually set any data on it, just showed you how the
GeomParam could be created and given a per point scope.

[Paul Winex]

I found this example
https://github.com/autodesk-adn/Maya-devkit/blob/master/win/devkit/plug-ins/AbcBullet/AttributesWriter.cpp#L371

http://docs.alembic.io/python/alembic/abcg.html#alembic.AbcGeom.ODoubleGeomParam
Where is subscription about arguments?
I cant found any python example how to pass data to ODoubleGeomParam



пятница, 13 ноября 2015 г., 2:12:55 UTC+4 пользователь Lucas написал:

> email to alembic-discussion+unsub...@googlegroups.com.

[Paul Winex]

I found another example with GeomParam

http://lists.blender.org/pipermail/bf-blender-cvs/2015-March/075137.html

Some interesting lines

m_param_colors = OC3fGeomParam(geom_props, "colors", false, kVertexScope, 1, 0);
...
std::vector<V3f> colors_buffer;
...
OV3fGeomParam::Sample colors = paths_create_sample_colors(*m_pathcache, *m_totpath, totkeys, colors_buffer);
...
m_param_colors.set(colors);
...
m_param_colors.set(OC3fGeomParam::Sample(C3fArraySample(path_sample.colors), kVertexScope));

i cant fount C3fArraySample class in python

[Paul Winex]

I have this code to build array data

mesh_samp = OPolyMeshSchemaSample(

        p_points, p_faceIndices, p_faceCounts

       )

mesh.set(mesh_samp)

arb = mesh.getArbGeomParams()
mass = ODoubleGeomParam(arb, "mass", False, GeometryScope.kVertexScope, 1)
array = Float64TPTraits.arrayType( len(p_points) )
for i in range( len(p_points) ):
    array[i] = 1.23
mass_samp = ODoubleGeomParamSample()
mass_samp.setVals( array )

how i can applay this data (array) to mesh_samp?

[Paul Winex]

Its WORK!

arb = mesh.getArbGeomParams()
mass = ODoubleGeomParam(arb, "mass", False, GeometryScope.kVertexScope, 1)
# create array
array = Float64TPTraits.arrayType( len(p_points) )

for i in range( len(p_points) ):
array[i] = 1.23

samp = ODoubleGeomParamSample()
samp.setVals( array )
mass.set(samp)

I have point attribute mass in houdini!

Now i need to write PRIMITIVE attribute

[Paul Winex]

https://gist.github.com/paulwinex/8b53ed7543910974c10d

This example with export point, vertex and prim attributes. Now i will try to export vector data.

[Paul Winex]

# point attrib vector
color = OV3fGeomParam(arb, "Cd", False, GeometryScope.kVertexScope, 1)
array = P3fTPTraits.arrayType( len(p_points) )

for i in range( len(p_points) ):

   array[i] = V3f(1.0, 0.0, 0.0)
samp = OV3fGeomParamSample()
samp.setVals( array )
color.set(samp)

Part for vector attribute

Now i need to export groups. Any ideas? Tt seems that alembic does not support point group.

[Paul Winex]

Alembic support poly groups only. This code create group with faseSets

# example array
arr = Int32TPTraits.arrayType(4)
for i in range(4):
    arr[i] = i
# create face set
samp = OFaceSetSchemaSample()
samp.setFaces(arr)
# write to mesh
faceSet = mesh.createFaceSet('my_group_1')
faceSetSchema = faceSet.getSchema()
faceSetSchema.set(samp)

[Paul Winex]

Full example!

https://gist.github.com/paulwinex/6814446f292d7eab822a

[Paul Winex]

Next step - UV, Normals and animation...

[Paul Winex]

UVs, Normals and animation

https://gist.github.com/paulwinex/aae3751e168a3ddb31e3

I think is enough to start develop main application. Thanks )))