Hey guys

How do I apply alembic point cache on to a static mesh in Houdini ?

I have exported out two alembic files from XSI, one which has the static geometry basically the first frame of the animation and the other one just a point cache of the animation. I'm not sure how to apply these point positions to the static geo. Any help much appreciated

Thanks
-J

Any ideas ??

i have only looked at the options but you could set ithe imported animating file to import as points and with a vop sop input the static gemoetry as the first input and the animated geometry as the second. use the import_attrib vop to import the second inputs P and apply that to the first input.
I have not used alembic my self so this is your better than nothing responce.

Have a look at the Alembic Procedural SHOP.

You can specify the first alembic archive (the deformed one?) and then supply the static alembic archive path in the Attribute File parameter where your other attributes will be added to the deformed mesh for shading and rendering purposes (like rest, uv's, vertex normals, etc.) in the render-time procedural.

Note that both abc archives need to contain the same alembic primitives.

You need to reference the Alembic Procedural SHOP to your object's procedural shader parameter for this to render correctly.

An alembic primitive is deferred rendered to the viewport and Mantra (via the alembic procedural). Houdini doesn't own the geometry. It is represented as a single point with intrinsic primitive attributes referenced from the Alembic archive object on disk. The geometry spreadsheet viewing Primitive attributes has a new Intrinsic option in the upper right where you can view intrinsic properties for your Alembic archive object.

The only two intrinsic attributes you can currently change are the transform (via the Transform SOP or object transform parameters) and the current frame. These are streamed in to the graphics card when changed which in turn references the correct frame for the alembic primitive. All deferred.


The only other way to directly drive the points is to import/convert the alembic delay load primitives in to polygons and then do the standard point position overrides.

Thanks Jeff.
But I'm just curious whether it would work the other way. Is it possible to use a static geometry as render geometry (Alembic File) and use the point cache as the Attribute file and transfer “P” attribute from the Attribute File to the static geometry so that it applies the point positions to the static geometry ?

Thanks
-J

jagadeesh
Thanks Jeff.
But I'm just curious whether it would work the other way. Is it possible to use a static geometry as render geometry (Alembic File) and use the point cache as the Attribute file and transfer “P” attribute from the Attribute File to the static geometry so that it applies the point positions to the static geometry ?

Thanks
-J

The Alembic procedural uses the bounding box on the geometry, so the primary file has to be the animated version. Also, for the Alembic procedural to match attributes, the topology has to match.