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.

The scene file can be downloaded here.

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):

Teapot001Shape or Teapot002Shape

_{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:

_{ArnoldLight001 disabled}

Set Parameter: Sphere Utility Shader

Now we will change the overlay_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}