In this Houdini VEX tutorial, we dive into the classic workflow of the golden duo: xyzdist() and primuv(). With just a short piece of code, we can make particles behave like a radar—scanning the environment, detecting how close they are to obstacles, and using primuv() to accurately fetch the surface normal for calculating repulsion forces. This technique is not only essential for obstacle avoidance and grounding effects in Crowd Simulation, but it is also a fundamental skill for any geometry-interaction task in Houdini, such as surface adhesion, attribute sampling, and guided motion. #houdini #houdinifx #CrowdSimulation #crowd #houdinitutorial