Describes a USD PreviewSurface material as of October 2019 found here: https://graphics.pixar.com/usd/docs/UsdPreviewSurface-Proposal.html
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| | MAXON_RESOURCE_DATABASE_SCOPE ("net.maxon.material.portbundle.usdpreviewsurface") |
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| | MAXON_ATTRIBUTE (Color, DIFFUSECOLOR, "diffuseColor") |
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| | MAXON_ATTRIBUTE (Color, EMISSIVECOLOR, "emissiveColor") |
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| | MAXON_ATTRIBUTE (InternedId, WORKFLOW, "workflow") |
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| | MAXON_ATTRIBUTE (void, WORKFLOW_ENUM_SPECULAR, "specular") |
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| | MAXON_ATTRIBUTE (void, WORKFLOW_ENUM_METALNESS, "metalness") |
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| | MAXON_ATTRIBUTE (Color, SPECULARCOLOR, "specularColor") |
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| | MAXON_ATTRIBUTE (Float, METALLIC, "metallic") |
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| | MAXON_ATTRIBUTE (Float, ROUGHNESS, "roughness") |
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| | MAXON_ATTRIBUTE (Float, CLEARCOAT, "clearcoat") |
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| | MAXON_ATTRIBUTE (Float, CLEARCOATROUGHNESS, "clearcoatRoughness") |
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| | MAXON_ATTRIBUTE (Float, OPACITY, "opacity") |
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| | MAXON_ATTRIBUTE (Float, OPACITYTHRESHOLD, "opacityThreshold") |
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| | MAXON_ATTRIBUTE (Float, IOR, "ior") |
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| | MAXON_ATTRIBUTE (Vector, NORMAL, "normal") |
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| | MAXON_ATTRIBUTE (Float, DISPLACEMENT, "displacement") |
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| | MAXON_ATTRIBUTE (Float, OCCLUSION, "occlusion") |
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◆ MAXON_RESOURCE_DATABASE_SCOPE()
| maxon::MATERIAL::PORTBUNDLE::USDPREVIEWSURFACE::MAXON_RESOURCE_DATABASE_SCOPE |
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"net.maxon.material.portbundle.usdpreviewsurface" |
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◆ MAXON_ATTRIBUTE() [1/16]
| maxon::MATERIAL::PORTBUNDLE::USDPREVIEWSURFACE::MAXON_ATTRIBUTE |
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Color |
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DIFFUSECOLOR |
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"diffuseColor" |
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) |
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When using metallic workflow this is interpreted as albedo.
◆ MAXON_ATTRIBUTE() [2/16]
| maxon::MATERIAL::PORTBUNDLE::USDPREVIEWSURFACE::MAXON_ATTRIBUTE |
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Color |
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EMISSIVECOLOR |
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"emissiveColor" |
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) |
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◆ MAXON_ATTRIBUTE() [3/16]
| maxon::MATERIAL::PORTBUNDLE::USDPREVIEWSURFACE::MAXON_ATTRIBUTE |
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InternedId |
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WORKFLOW |
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"workflow" |
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) |
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This node can fundamentally operate in two modes : Specular workflow where you provide a texture/value to the "specularColor" input. Or, Metallic workflow where you provide a texture/value to the "metallic" input.
Specular Workflow: Specular color to be used. This is the color at 0 incidence. Edge color is assumed white. Transition between the two colors according to Schlick fresnel approximation.
Metalness Workflow: Use 1 for metallic surfaces and 0 for non-metallic.
- If metallic is 1.0, then F0 (reflectivity at 0 degree incidence) will be derived from ior ( (1-ior)/(1+ior) )^2, then multiplied by Albedo; while edge F90 reflectivity will simply be the Albedo. (As an option, you can set ior to 0 such that F0 becomes equal to F90 and thus the Albedo).
- If metallic is 0.0, then Albedo is ignored; F0 is derived from ior and F90 is white. In between, we interpolate.
◆ MAXON_ATTRIBUTE() [4/16]
| maxon::MATERIAL::PORTBUNDLE::USDPREVIEWSURFACE::MAXON_ATTRIBUTE |
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void |
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WORKFLOW_ENUM_SPECULAR |
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"specular" |
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) |
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◆ MAXON_ATTRIBUTE() [5/16]
| maxon::MATERIAL::PORTBUNDLE::USDPREVIEWSURFACE::MAXON_ATTRIBUTE |
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void |
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WORKFLOW_ENUM_METALNESS |
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"metalness" |
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) |
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◆ MAXON_ATTRIBUTE() [6/16]
| maxon::MATERIAL::PORTBUNDLE::USDPREVIEWSURFACE::MAXON_ATTRIBUTE |
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Color |
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SPECULARCOLOR |
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"specularColor" |
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) |
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Specular color to be used. This is the color at 0 incidence. Edge color is assumed white. Transition between the two colors according to Schlick fresnel approximation.
◆ MAXON_ATTRIBUTE() [7/16]
| maxon::MATERIAL::PORTBUNDLE::USDPREVIEWSURFACE::MAXON_ATTRIBUTE |
( |
Float |
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METALLIC |
, |
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"metallic" |
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) |
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Use 1 for metallic surfaces and 0 for non-metallic.
- If metallic is 1.0, then F0 (reflectivity at 0 degree incidence) will be derived from ior ( (1-ior)/(1+ior) )^2, then multiplied by Albedo; while edge F90 reflectivity will simply be the Albedo. (As an option, you can set ior to 0 such that F0 becomes equal to F90 and thus the Albedo).
- If metallic is 0.0, then Albedo is ignored; F0 is derived from ior and F90 is white. In between, we interpolate.
◆ MAXON_ATTRIBUTE() [8/16]
| maxon::MATERIAL::PORTBUNDLE::USDPREVIEWSURFACE::MAXON_ATTRIBUTE |
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Float |
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ROUGHNESS |
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"roughness" |
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) |
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Roughness for the specular lobe. The value ranges from 0 to 1, which goes from a perfectly specular surface at 0.0 to maximum roughness of the specular lobe. This value is usually squared before use with a GGX or Beckmann lobe.
◆ MAXON_ATTRIBUTE() [9/16]
| maxon::MATERIAL::PORTBUNDLE::USDPREVIEWSURFACE::MAXON_ATTRIBUTE |
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Float |
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CLEARCOAT |
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"clearcoat" |
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) |
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Second specular lobe amount. The color is white.
◆ MAXON_ATTRIBUTE() [10/16]
| maxon::MATERIAL::PORTBUNDLE::USDPREVIEWSURFACE::MAXON_ATTRIBUTE |
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Float |
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CLEARCOATROUGHNESS |
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"clearcoatRoughness" |
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) |
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Roughness for the second specular lobe.
◆ MAXON_ATTRIBUTE() [11/16]
| maxon::MATERIAL::PORTBUNDLE::USDPREVIEWSURFACE::MAXON_ATTRIBUTE |
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Float |
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OPACITY |
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"opacity" |
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) |
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When opacity is 1.0 then the gprim is fully opaque, if it is smaller than 1.0 then the prim is translucent, when it is 0 the gprim is transparent. Note that even a fully transparent object still receives lighting as, for example, perfectly clear glass still has a specular response.
◆ MAXON_ATTRIBUTE() [12/16]
| maxon::MATERIAL::PORTBUNDLE::USDPREVIEWSURFACE::MAXON_ATTRIBUTE |
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Float |
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OPACITYTHRESHOLD |
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"opacityThreshold" |
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) |
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The opacityThreshold input is useful for creating geometric cut-outs based on the opacity input. A value of 0.0 indicates that no masking is applied to the opacity input, while a value greater than 0.0 indicates that rendering of the surface is limited to the areas where the opacity is greater than that value. A classic use of opacityThreshold is to create a leaf from an opacity input texture, in that case the threshold determines the parts of the opacity texture that will be fully transparent and not receive lighting. Note that when opacityThreshold is greater than zero, then opacity modulates the presence of the surface, rather than its transparency - pathtracers might implement this as allowing ((1 - opacity) * 100) % of the rays that do intersect the object to instead pass through it unhindered, and rasterizers may interpret opacity as pixel coverage. Thus, opacityThreshold serves as a switch for how the opacity input is interpreted; this "translucent or masked" behavior is common in engines and renderers, and makes the UsdPreviewSurface easier to interchange. It does imply, however, that it is not possible to faithfully recreate a glassy/translucent material that also provides an opacity-based mask... so no single-polygon glass leaves.
◆ MAXON_ATTRIBUTE() [13/16]
| maxon::MATERIAL::PORTBUNDLE::USDPREVIEWSURFACE::MAXON_ATTRIBUTE |
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Float |
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IOR |
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"ior" |
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) |
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Index of Refraction to be used for translucent objects.
◆ MAXON_ATTRIBUTE() [14/16]
| maxon::MATERIAL::PORTBUNDLE::USDPREVIEWSURFACE::MAXON_ATTRIBUTE |
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Vector |
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NORMAL |
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"normal" |
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) |
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Expects normal in tangent space [(-1,-1,-1), (1,1,1)] This means your texture reader implementation should provide data to this node that is properly scaled and ready to be consumed as a tangent space normal.
◆ MAXON_ATTRIBUTE() [15/16]
| maxon::MATERIAL::PORTBUNDLE::USDPREVIEWSURFACE::MAXON_ATTRIBUTE |
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Float |
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DISPLACEMENT |
, |
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"displacement" |
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) |
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Displacement in the direction of the normal.
◆ MAXON_ATTRIBUTE() [16/16]
| maxon::MATERIAL::PORTBUNDLE::USDPREVIEWSURFACE::MAXON_ATTRIBUTE |
( |
Float |
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OCCLUSION |
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"occlusion" |
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) |
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Extra information about the occlusion of different parts of the mesh that this material is applied to. Occlusion only makes sense as a surface-varying signal, and pathtracers will likely choose to ignore it. An occlusion value of 0.0 means the surface point is fully occluded by other parts of the surface, and a value of 1.0 means the surface point is completely unoccluded by other parts of the surface.