AbcMaterial
What is AbcMaterial?
AbcMaterial
is meant to help formalize material definitions and bindings within
Alembic. It’s important to understand it is not intended as a material
interchange format between renderers: AbcMaterial does not define
shading code, conventions or behavior. It’s designed for transfer of
target-specific material information between applications, NOT for
translation of shaders between targets.
AbcMaterial is a peer of
AbcGeom, and the way it works is by defining a schema for a material
definition which can act as a standalone object or as supplemental data
attached to another object. AbcMaterial also defines conventions and
utilities for binding and resolving material assignments and overrides.
It does not define what a material schema should actually contain (the
way AbcGeom does with well-defined geometry types such as cameras or
meshes) since it would be impossible to accomodate all of the many
variations in material standards that exist today. Instead, a material
schema contains the shader names, parameters and connections for one or
more named targets (such as "maya", "mentalray", "arnold", "prman",
"glsl", etc.). Shaders may be specified in both monolithic and networked
form.
In general terms, the AbcMaterial library allows you to:
- describe
target-specific materials as sets of shaders, with their list of named
and typed parameters, as well as their parameter values
- describe inheritance relationships between materials
- describe
networked materials (the nodes that they're composed of, their public
interface, and any parameters set on said interface)
- assign materials to locations in an Alembic file - this is done either by:
- describing the material directly as a child compound on that location
- specifying an assignment with a full path to an alternate location in the alembic file where the material is described
- override material parameter values at each geometry location the material is assigned to
For a quick start, the simplest is probably to look at the AbcMaterial/Tests/MaterialAssignAndFlattenTest.cpp example.
