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Primitives

How to use the UsdRender primitives in order to output an image.

Relationship

In USD, all you need to render is a couple of primitives:

  • RenderSettings
  • RenderProduct
  • RenderVar

Their relationship is described as: 

erDiagram
    RenderSettings {
        relationship products "/Render/Products/renderproduct"
    }

    RenderProduct {
        relationship orderedVars "RenderVar A, RenderVar B, RenderVar C"
    }

    RenderVarA {
        string sourceName "Beauty"
    }

    RenderVarB {
        string sourceName "CombinedDiffuse"
    }

    RenderVarC {
        string sourceName "CombinedEmission"
    }

    RenderSettings ||--o| RenderProduct: "produces"
    RenderProduct ||--|| RenderVarA : "consumes"
    RenderProduct ||--|| RenderVarB : "consumes"
    RenderProduct ||--|| RenderVarC : "consumes"

Which translates this way into Houdini Solaris:

None

Warning

Do not forget to modify the parameter of each primitive: add the RenderVars through Ordered Render Vars inside the RenderProduct, then add the RenderProduct to the RenderSettings through the Ordered Products parameter.

Tip

As described in Render Globals > Variants , you can order the RenderVars. Taking Arnold as an example, where the Beauty is called RGBA , you'll use /Render/Products/Vars/RGBA /Render/Products/Vars/** inside the RenderProduct Ordered Render Vars parameter to have RGBA prepended to the RenderVars list, so switching to the Arnold Hydra delegate will immediately show the right RenderVar.