This TouchDesigner tutorial focuses on the Projection POP as a way to create real-time interactive 3D scenes that react to 2D texture inputs. It touches on the difference between screen-space and camera-space, and goes through the step-by-step process of creating interactive grass that grows from the surface of a twisted torus mesh. While this tutorial looks at using a mouse driven circle TOP texture, the technique is easy to extend to any video input, such as silhouettes segmented from RGB or depth cameras.
This tutorial uses build 2025.32460, so if you're using an older or newer version there may be features that don't work in exactly the same way.
Tutorial resources:
HDRI from Poly Haven
Tutorial Project File
Camera Input Example
Links mentioned in the tutorial:
Lucas Morgan’s "Interactive Guided Tour Through Matrix Transformation Pipelines
Bullet Solver and TDAbleton in TouchDesigner
