Alembic Documentation

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Alembic


Alembic is an interchangeable computer graphics file format developed by Sony Pictures Imageworks and Industrial Light & Magic. It was announced at SIGGRAPH 2011 and has been widely adopted across the industry by visual effects and animation professionals. Its primary focus is the interchange of geometry (models) between different groups working on the same shots or same assets. Alembic supports the common geometric representations used in the industry, including polygon meshes, subdivision surface, parametric curves, NURBS patches and particles. Alembic also has support for transform hierarchies and cameras. Alembic specifically is not focused on storing the complex dependency graphs of procedural tools but instead stores the "baked" results.
 

For our purpose, the important is the very last sencence of definition above. We use Alembic to bake complex animation into the vertices animation and play it in the engine – for example explosion of Tamlberk gate after being hit with cannon ball. This explosion was simulated in 3ds Max and then baked into vertex animation. Another example is the sand inside the sandglass.

How to export Alembic

Alembic export should be very straightforward, however we experienced problems instead. Not every Alembic file works in the engine, you will probably have to play with different exporters, different formats... 

  • 3ds Max built-in Alembic exporter
  • External Alembic plugins – Exocortex

File format: .ABC

Alembic in Editor

  • Insert Alembic via Entity -> GeomCache.
  • Load the .ABC file into the File property of entity. Compile Alembic window pops-up:

          Alembic Documentation image1.png

  • You can keep default parameters and hit OK. If everything goes well, there should be no error displayed and the .ABC file in the entity properties is replaced with compiled.cax file.
  • From now on, you will use this .cax file unless you need to recompile .ABC again .
  • On your harddrive, you can notice one more file – .cbc file contains parameters used to compile .cax.
  • Submit all three abovementioned files.