[[21-01-01-Pipes]]

https://youtu.be/H-RYtuacUlM

USD

http://www.usdmanager.org/about.html

Root layer stack Paradigm

Primitives: fundamental building blocks / hierarchical structure. Primary container object.
Properties: named * typed data on primitives / attributes & relationships. Secondary container object.
Paths: (Namespace) precise locations in the scene hieratchy / primitives & properties (like a file paths on disk)
Layers: bundles of primitives and other properties / vontains opinions / in-memory & ment to be saved on disk
Layer Stacks: ordered collection of contributing layers (sublayers)
Root Layer Stacks: foster collaborative workflows / common scene description / no one has to build their scene

Stage Scene (loadeld file / composed)
Model - Everything that contribute to asset with exclusive ‘kind’ type.
- only group model prims can have oyher model children.
- A prim can only be a model id its prim is also (group) model
- No prrim should have exact kind ‘model’.
- find with calls in vex: usd_ismodel() usd_kind() python: UsdPrim::IsModel UsdModelAPI::GetKind

Primary container object: Primitives and Attributes (secondary).
Primitives can contain other Primitives creating a namespace hierarchy on stage

We always work ‘against/relative’ to stage.

Worls vs local space (tarnsforms, velocity/acceleration, motion blur)
Duplicate date (e.g. subdiv settings/topology attributes) vs writing to sparsley
Use stage mertrics (fps/shutter sample count/material binding) to drive SOP settings.

ASWF Asset Structuring Guidelines

Kind

A method of defining hierarchy on primitives (like tag) help define role in hierarchy. In most pipelines should be automated. authoring: (like in sop import / configure primitive). Can help in selection. (can change behavior’s type in selection RMB menu)

All geometry is one component
Nested groups and component - Auto set: xform as group / geometry as component - component only on root levels
Nested assembly group and components - for dense hierarchy tree.
should be class primitive and models will inherent from it.

/Models <group
  /Characters <group  
    /CharacterA <assembly (ready to put in to scene)  
      /Skin <component
        /mesh
      /Addons <component
        /mesh
    /CharacterB <assembly (ready to put in to scene)  
  /Props  <group  
    /Props1 <assembly (ready to put in to scene)  
      /mesh  ??
      /mesh  ??

Component

Cannot contain groups or asemblies! Only able to contain Subcomponents. (most of time when import sops or smaller assets.)

component models are publishable assets that keep their geo behind a payload
most nasic asset published in a USD

Subcomponent

An important primitive inside a component (e.g. a door pivot)

Assembly

An important group. Usually a published asset or reference to one.
(ready to put in to scene)
Bring togheter other componenets

Assembly models are publishable assets which reference components or other assebly assets

Group

Can contain components, groups, or assemlies. Most flexible.

Properties ?

Selectors

?? Selectors:

Leaf geometry - Leaf - ‘end of a hierarchy branch’ no childs
Component
Subcomponent
Model
Group
Assembly
Point Instance (top level)
Point Instance (leaf)

Purpose

configure primitive node.

Layers

Need to export can set in SOP import or Configure layer

#### Variant layers can be stored separat files or all in one layer

one file - reduce num of layers / somple management
multiple - easier for tools or pipelines (like for layout lop in solaris)

I/O

Save control:

Implicit - will save layer on usd path . so path not set. Not clean. Better have controll.
Save Path

Composition arc

LIVRPS hierarchy:

Opinion strength ordering in each LayerStack- overrides permissions when merging you can use same asset and it will use one with stronger opinion.

Locals / Sublayers - A file on disk stacked with strenght order. Combine like photoshop (sublayers per department or steps like geo, mat… )
Inherets - Like C++ classes. (keep insances alive). manage materials.
VariantSet - Variant is single named variation of VariantSet (primitiv located in scene graph) / lod, variations… - For switching between items in a collection.
References - Add a new item to your scene
Payloads - - References with optional deferred loading. Optimization’s (not to load until they are needed)
Specials - materials tweaks - Inherits with some special properties.

Formats

refer to geo in hierarchical way. Can be extended by plugins to use other formats
.usd - [binary] or [ASCII]
.usdc [binary] Crate files. -Compressed, faster to access. Best for large geo.
.usda - [ASCII] human readable format. For debug and experiment, can open like usd
.usdz - Support for collection of files in zip (like mesh and textures)

File Structure

file.usd > payload.usdc > geo.usdc / mtl.usdc

payload » what to show / load

Variant layers: separate file vs all in one layer

Setup Asset file inside USD !!!!!!!!!!!!!!!!!!!!!!!!!

Make scene with light to use all the time.

1) componentgeometry: import fbx file > https://youtu.be/HgEwvTjmrgE Outputs:

required - for render
proxy - viewport
simproxy

2) component material

3) material library

to 2op of componentmaterial
setup material x 4) component output
name it
thumb it
SAVE TO DISK

!!!!!!! now we have usd file. how to update ???

BRING BACK SAVED FILE
1) file node

import usd file 2) edit
i.e: editMaterial node.
- drag material from tree to node param details panel.

SOP

Authoring geometry for USD use:

In SOPs:
- name - Can drive Assemblies / Groups / Components
- path Primitive attributer - Can drive Assemblies / Groups / Components
- geometry Prim groups - USD Sub-component (geometry faces subset) useful but not part of composition ark
In LOPs: Load context: Use referencing vs … ?
- References - sub layering tree. Adding new props. multiple input can import same asset only as ref.
- Sublayers - attaching as a branch

## SOP <> USD

19:
Asset import
Add asset to library



### Component nodes
can quickly setup constructed asset  


18.5:  
Usd like packed primitives  

In SOP:
- SOP geometry prim groups
- Organized by 2 attributes `@name` + `@path` (prim) - with name in the end: `s@path = "/basicFolderForSolaris/" + s@name;` so path will be: /Folder/name (`/` is important)
   - s@path = "/Barrels/next level/ name" + s@name; -  name change tree  ROOT !!
   - s@path = "Barrels/next level/ name" + s@name; -  name change tree   RELATIVE PATHG !! (import path prefix in import sop LOP  now is dynamic)
In LOP:
- USD Assemblies, Groups, Components
- USD SubComponents, limited, only for materials .

### [usdexport] SOP
nested assembly, group and components.

Assemble SOP & geo SubsetGroups

IN SOPS: Assemble SOP can help with exporting to lops. > create groops. » In LOPs Subset Groups (are attributes of primitive. )

https://youtu.be/DI09YJLZ_6k?t=1472

LOP

Solaris Viewport

Stage - node view.
Scene Graph Tree - Outliner with scene graph compose tree.
- Scene Graph Path /
- Primitive type: - xform, mesh /
- Vatiants /
- Kind - assembly, group, component. ()
Scene Graph Layer -
Layout Asset Gallery - Asset Library

Input

[SOP Create] LOP

- subset groups like attrib / groups for assign materials

##### Load Layer
Open disk file

##### Sub Layer
Open disk file or  merge

[SOP Import] LOP

Load From Sops.

Load as reference checkbox.
Packed Primitives how to pack primitives.
- Create point instancer - grab prototype. much optimised !!!! with much of points. (or for sim)
- Native Instances - (prototype + huge hierarch blue instances )
- Xform - kill instances
- Unpack - kill instances without nulls
Kind authoring
Layer save path - good to set a destination $HIP/..usd.

Subset groups to preserve groups !!!

[SOP Scene Import] LOP

Import all from SOPs

[Stage manager] LOP

by drag and drop.

[Reference] LOP

Variants

Add Variant to existing primitives

Loop for adding variants.

Primitive path - set path to primitives u want to make variants for,

Set Variant

Set one —

SOP Modify LOP
USD Configure SOP

Collection

Collection LOP will author a collection primitives. like selction set. - will be saved in file. (overal usd) Can add material to collection.

Geometry subsets

scale well, can attach materials

Materials

Material Library Assign material Material Variation https://youtu.be/EcMq_DH-DnM

Out

Configure Layer

Write asset to disc.

USD ROP

Write to disc

Manage

Prune

Isolate (Primitive pattern)

Merge

Will create separated layers

Configure Primitives

Purpose: Render(tylko w karmie)/Proxy(tylko w hydrze)/Guide

Procedurals

Add Variant

Material

Way to assign material:

SOP path & name prim attributes > USD Assemblies/Group/Components
SOP Geometry Prim Groups > USD Sub-Components

Material Library

We can assign material to whatever level of hierarchy

Save with asset or alone ? - Zmienić materiał Path z - materials na barrel

Use auto fill - will create folder and import SOP mats
- Material network > browse to mat context and choose existing materials even from SOPs
- USD Path Prefix >
To assign geometry to created library in Geometry Path
- drag and drop geo from: Scene graph tree to get explicit path
- write a filter ie; *geo* to assign by name
Add new by hand
- Material VOP - path to material ../../mat/NameOfMyMat
- Material Path - we can name
- Geometry Path - as in pt 2.

material linker ??? more artistic visual than mat assign (For procedural)

Assign Material

Same less options

[Layout] LOP node

brush
edit

insertion points! nod allow to move edits upstream !

instance

stage manager > to folders collection > (name from folder) instancer > %foldername )and add point inside !_

1) scene import - import all < will be slower you need bake it and read in later.  - u can filter
2) not portable because have no folders so
   - destination path >> JAKIŚ_GLOWNY_FOLDER         (see prev in scene graph tree)
   - later be more specyfic and build hierarchy of your needs
we will divide by layers


LAYERING:
Sublayer LOP node <
1) import rest pose
2) sublayer anim
it will update only differences !!! (po prawej a wieksza opnie )
can set OPINIONS by: layer position


@Cd >> W USD: displayColor

MAT:
1) Mat lib
 - matx subnet.  >> mtlx standard
 - BEFORE PLUGIN BASE COLOR: convert jpg to aces ACES: karma_OCIO_transform  Utility - Linear - sRGB  >> ACES - ACEScg
 - BEFORE PLUGIN NORMAL:
 - mtlxgeometrycolor - vertex color // or geompropvalue z parametrem displayColor (Cd in sops)
-
2) assign mat
 -primitives: drag geo from scene graph
 - material path:
 - drag material from scene graph

LIGHT:

USD WORKFLOW !!!!!

1) reference < otworz
x) usd rop < zapisz
...?


VARIANTS:
- like lod i mozesz zmieniac
- 

USD