This short tutorial will cover how to use the set_parameter, collection, and disable operators to change the lights and self-shadowing of some teapots and alter the shading of the sphere. The scene contains two lights casting shadows on three teapots and a sphere with a simple utility shader assigned to it.

Use the Ignore Operators flag in Diagnostics> Feature Overrides to check what the render looks like without any operators.

The scene file can be downloaded here.

• Start by opening the Arnold Operator Network Editor (Render Settings > Main > Advanced).

Collection

We will use the Collection operator to reference a selection. This can be used to avoid writing a selection multiple times (optional in this case).

• Create a Collection Operator containing two teapots. Under Selection add the following (we will apply a Set Parameter that will only affect these two teapots):

_{Teapot Collection}

Set Parameter (Disable Self Shadows on the Teapots)

• Create a Set Parameter. Create the following expression:

self_shadows=false

Disable Light

We can turn off one of the lights by using the Disable operator.

• Create a Disable operator and under Selection enter for the following Arnold light:

Arnold quad.light.1 (d rag & drop the light node)

_{Arnold quad_light.1 disabled}

Set Parameter: Sphere Utility Shader

Now we will change the O verlay Mode for the spheres Utility shader.

• Assign a Utility shader to the sphere and rename it to the_utility.
• Create another Set Parameter and under Expression enter the following:

overlay_mode="wire"

• Under Selection enter the following:

_{Utility shader altered with Set Parameter}

_{Final Operator Graph window setup}