# Solaris

Woo hoo


## General

- This is the same as sops, where the geometry spreadsheet follows selection, the viewport follows the display flag.
- USD jargon is unavoidable at some point, but I think its possible to dive in without getting too caught in the weeds.
- Connecting sopimport nodes appends their results, as opposed to sops which does chains of geometry modification, or connecting /obj nodes which does parenting operations. 
- In sops a primitive is a renderable thing, like a polygon, a curve, a volume. In USD a primitive means a thing in the Scene Graph Tree. So in that outliner style way of thinking, a folder is a primitive, a shape is a primitive, a transform is a primitive. Pretty much any element you see in the Scene Graph Tree is a primitive. 
- Primitives and attributes are the two primary namespace objects in USD
- Primitives are the primary container object in USD. 
- if its just a group. use scope rather than xform 
- If you are going to use LOPs in the end for rendering, why not create geometry under SOP Create instead? 
  - You could but there is some gotchas mainly its the update frequency.
  - LOPS was designed to accommodate USD. And USD is for cached data. It cannot fully accommodate the dynamic creation of SOPs. 
  - So you might have to update LOPS viewport everynow and then. 
- Context Options Editor
- Load as reference vs Make Instanceable. 
  - In other DCC, instanceable is what they by reference. You can't edit. Just a reference.
  - In Solaris, when you make it as a reference. You can still edit it. 
- Model in USD is not the same as Model in 3D. HAHAHA
- The standard “RS Material” (A) output VOP is not compatible with Solaris but a “RS USD Material” (B) output VOP was added that automatically works in both Houdini and Solaris. 
- Note that the material flags have been disabled on the two individual shaders and only the Collect node has its material flag enabled since the Collect VOP is the only material that needs to be assigned to the rubbertoy. 
- Before a material can be assigned to geometry in Solaris its path must have been previously defined in the Scene Graph Tree before assignment. 
- There are two primary LOP nodes that can be used to apply shaders to geometry in Solaris.

    Material Library LOP - Can create and assign shaders to objects.

    Assign Material LOP - Only assigns shaders to objects but has more controls for overriding material assignments.
- Render Product LOP - Only required if rendering Redshift AOVs, defines a collection of AOVs. 
- Render Settings LOP - Required to render, controls the Redshift render settings.
- USD Render ROP - Required to render, sets which render delegate to use and initiates the render operation.
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## Some Nodes

- SOP Import (To import from SOP)
- SOP Create
- Configure Primitive
- Prune
- Variant Block
- Set Variant 
- Transform 
- Simulation Proxy
- Reference (To import existing USD or if you want to use the inputs. SOP Create + Material Library)
- Stage Manager (Manipulate the path llike drag and dropping)
  - Like a crude file browser.
  - Never plug on top of this node as it flattes everything out (i.e when an upstream asset gets updated, it does not get updated downstream)
- Material Library
- Assign Material 
- Component Builder (Introduced in 19.0. One of the handy node network to create your USD assets)
- Scene Import
- Merge
- Insertion Point
- Graft Stages
- Sublayer 
- Light Mixer
- SOP Modify
- Material Linker
- Configure Layer
- Duplicate
- Use a Render Geometry Settings LOP to add per-object Redshift options to geometry in the scene.
- Use a Render Settings LOP and a USD Render ROP to export proxies from Solaris.
  - A Camera must be included with the proxy or the proxy export will fail.
- Transform vs Xform (Former is actually moving around. Xform is just a representation in the graph)
- Layer Break (Layer breaks are very important to understand. They give you control over what is written to layer file on disk.)
- USD prim var reader.
  - Cd becomes display color
  - UV becomes ST 
- Render Geometry Settings
- Asset Reference (19.0. This node combines the most common features of the Reference, Xform, and Set Variant LOPs into a convenient tool.)
- Restructure Scene Graph
- Modify Path
- Layer Break
- **USD Render ROP vs USD Rop**

## Shortcut

- `Shift + R`. Karma to OpenGL 
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## Geometry Variants 

- Component Geometry Variants. 

## Material Variants