Class

Shape

Synopsis
USD kitchen set asset available here.
NVIDIA USD attic asset available here.

 

A procedural node that is capable of reading USD files.

 

 


sidedness

Just like you can disable the visibility for specific ray types, you can also change an object's sidedness depending on the ray type. By default, objects are double-sided for all rays. By unclicking any of these checkboxes, the object will become single-sided, which means that those parts of the object whose normal vector points away from the incoming ray direction will not be rendered.

receive_shadows

Determines whether or not the object picks up shadows from other objects.

self_shadows

Determines whether or not the object casts shadows on itself.


invert_normals

Invert normals (so that normals face inwards and not outwards).

ray_bias

Raytrace bias value specified for the object.

matrix

Transformation matrix. This can be either a single matrix or an array of matrices that define the SRT motion of the object for the current frame (the matrices define the motion for the full-frame, not just between the shutter open - close time).

shader

An array of nodes pointing to the shader or shaders in the case of per-face shader assignment.

opaque

As of Arnold 5.3, this flag is set automatically by changing the opacity or transmission on a material.

Determines whether the object is considered opaque (transparent). By default, Arnold built-in shaders set the opaque flag automatically, based on whether or not the shader settings would require disabling the opaque flag on the object to render correctly. For example, it's no longer necessary to manually disable the opaque flag to get transparent shadows for a glass shader.


Exceptions are curves and points when min_pixel_width is in use, and OSL shaders.  



use_light_group

A boolean to enable selective light linking

light_group

An array of nodes pointing to the lights that will affect the node if use_light_group is enabled.

use_shadow_group

A boolean to enable selective shadow linking.

shadow_group

An array of nodes pointing to the lights that will not cast shadows on the polymesh, if use_shadow_group is enabled.

trace_sets

An array of strings each of which names a trace set. A custom shader must be used to make effective use of these strings via the AiShaderGlobalsSetTraceSet and the AiShaderGlobalsUnsetTraceSet API calls.

It is possible to tag objects to be part of one or many trace sets. The trace_set shader tags specific rays with an inclusive or exclusive trace set. Both geometry and rays can be tagged with trace sets:

  • A piece of geometry can have none or any number of trace set tags.
  • A ray can optionally have one trace set tag, and it can be exclusive or inclusive.


The way those two tags interact makes it possible to control visibility for specific rays:

  • A ray with no trace set will hit all geometry.
  • A ray tagged with an inclusive trace set will only hit geometry which has that trace set tag.
  • A ray tagged with an exclusive trace set will only see geometry that does NOT have that trace set tag.

motion_start

The time at which the first motion key of the shape is sampled. Other motion keys must be uniformly spaced within this range. Times can be absolute or relative as long as shutter and motion times use the same convention. By convention, the times are frame relative. For example, start and end times -0.5 to 0.5 indicate that two motion keys will be sampled midway between the previous and current frame, and the current frame and next frame. This is applied to cameras, lights, and shapes.

motion_end

The time at which the last motion key of the shape is sampled. Other motion keys must be uniformly spaced within this range. Times can be absolute or relative as long as shutter and motion times use the same convention. By convention, the times are frame relative. For example, start and end times -0.5 to 0.5 indicate that two motion keys will be sampled midway between the previous and current frame, and the current frame and next frame. This is applied to cameras, lights, and shapes.

id

Unique ID for a node in the Arnold scene. 

override_nodes

Nodes inside the procedural can be replaced by other nodes with this parameter. This may be used for example to replace shaders in an existing .ass procedural. When the parameter is enabled, nodes in the immediate parent scope of the procedural will replace identically named nodes inside the procedural.

namespace

Create nodes in this namespace if present.
operator

The operator graph is evaluated from the operator node defined here, denoted as the target operator.

filename
The path to the USD file.

object_path

Determines which USD primitive(s) are rendered. When empty (default), it will render the whole USD file.
frame
The frame number to expand in the procedural.
debug
Dumps verbose logs about the USD nodes being created.

threads

When set to zero or a negative value, it won’t detect the number of cores.

overrides

Serialized changes to be applied on top of the USD file, in USD ASCII format.

 

 

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