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n1ckfg

Jan. 17, 2018 09:38:27

So I need to extract vertex colours from an Alembic exported in Blender. I'm almost there–using the Python node I can get an empty array of Cd attributes:

import _alembic_hom_extensions as abc

def getAbcAttr(attrName):
    geo = hou.pwd().geometry()
    time = hou.frame() / hou.fps()
    
    if geo.findGlobalAttrib("abcFileName") is not None:
        url = geo.attribValue("abcFileName")

        for childGeo in abc.alembicGetSceneHierarchy(url, "/")[2]:  
            path = "/" + childGeo[0] + "/" + childGeo[2][0][0]
            
            x = abc.alembicArbGeometry(url, path, attrName, time)
            print(x) 
            
getAbcAttr("Cd")

From the abcls output below, can anybody tell me what I need to change in the script to get the attribute values?

/crv_GP_Layer_1_mesh_007/crv_GP_Layer_1_mesh_007Shape/.arbGeomParams:
CompoundProperty                   Cd {
                                    arrayExtent=1
                                    geoScope=fvr
                                    interpretation=rgba
                                    isGeomParam=true
                                    podExtent=4
                                    podName=float32_t
                                   }
/crv_GP_Layer_1_mesh_007/crv_GP_Layer_1_mesh_007Shape/Cd:
ArrayProperty       float32_t[4]   .vals[1] {
                                    arrayExtent=1
                                    geoScope=fvr
                                    interpretation=rgba
                                    isGeomParam=true
                                    podExtent=4
                                    podName=float32_t
                                   }

Enivob

Jan. 18, 2018 15:20:19

I submitted this as a Houdini bug but SESI claims it is a Blender export bug.
I have reported this to the Blender developers and there is some investigation in progress.
https://developer.blender.org/T53745 [developer.blender.org]

It is an interesting approach to try and pull the information directly from the .abc file, however.

Are you unpacking your Alembic before you run the Python?

n1ckfg

April 10, 2018 09:34:45

Yup, I'm unpacking, but the discussion at the link you provided seems to definitively confirm it's a Blender bug, not a Houdini problem. Thanks!