How-To

One page per thing a node or a graph can do. These are not written to be read in order. Each page states its goal, what it assumes you already have, the shape of the solution, how to confirm it worked, and what to check when it does not.

Both languages appear on the same page. Where CUDA and Slang differ, each is shown in its own tab rather than in a separate chapter. For the surface each task draws on, refer to Reference.

Write a Node

Task	Goal
Types and Values	Give a node a number, vector or matrix authored in USD, and read it in the GPU code.
Choose a Resource’s Backing	Decide whether a resource is texture-backed or buffer-backed, and bind it correctly.
Upload Your Own Data	Get a lookup table, a filter kernel or any authored array onto the GPU.
Control the Launch Geometry	Decide how many GPU threads run, and over what.
Compile It Yourself	Build the GPU code with your own toolchain, or split it across files.

Wire a Graph

Task	Goal
Chain Nodes	Feed one node’s output straight into the next, without publishing the intermediate.
Split and Join	Feed one node’s output to several consumers, or several producers into one node.
Publish, Overwrite and Read Back AOVs	Decide what a graph exposes to the rest of the pipeline, and get it back on the host.
Work Across Render Products	Read an AOV produced by a different RenderProduct, or drive several products at once.
Write a Node With No Input	Build an AOV out of authored values alone, with no AOV coming in.
Use a Built-In Node	Get a common operation without writing any GPU code.

Across Frames

Task	Goal
Keep State Across Frames	Let a node read what it wrote last frame.
Read a Previous Frame	Read an AOV as it was N frames ago.
Cache Work Across Frames	Compute something once instead of every frame.
Change Values and Rewire	Retune or rewire a graph without reloading the scene.

Reach Beyond an AOV

Task	Goal
Read a Sensor Composite	Consume a lidar or radar point cloud in a node.
Trace the Scene	Have a node render the scene itself rather than transform an AOV.

Slang Specifics

Task	Goal
Bind Resources and Descriptor Spaces	Place resources into specific descriptor spaces, and state a constant buffer’s layout.