What is cast3d?

cast3d is a small R package that turns a photo, or a short text description, into an interactive 3D model you can view and rotate right in a browser or inside a Shiny app. It works by sending the image to Tripo, an external AI service that builds 3D models from images, and getting back a GLB file, which is a common format for storing 3D shapes. Using it is meant to be simple. After installing the package from GitHub, a user sets up their Tripo API key once, then calls a single function that takes a photo and returns a finished 3D model. Behind that one function are smaller pieces that can also be used on their own: one that submits the image to Tripo, one that repeatedly checks whether the model is ready yet, one that downloads the finished .glb file to a local cache, and one that opens an interactive viewer built on the Three.js JavaScript library, complete with mouse controls to orbit around the model. Another function reports basic facts about a model, like how many vertices and faces it has and how large the file is. The API key can be set through the setup function or as a plain environment variable, and the package will pick it up automatically when loaded. For people building web apps with Shiny, cast3d includes ready made components so a generated 3D model can be dropped straight into a Shiny page and rendered as an interactive widget. Internally the package is organized in four layers: a bottom layer that handles authenticated requests to the Tripo API with retries and timeouts, a task layer that creates and polls generation jobs, a model layer that downloads files and reads their metadata, and a top viewer layer that wraps Three.js as an R htmlwidget. The example included in the project turns a photo of a bacteriophage into a viewable 3D model.