Abstract: We present a method for generating procedural volumetric fire in real time. By combining curve-based volumetric free-form deformation, hardware-accelerated volumetric rendering and Improved Perlin Noise or M-Noise we are able to render a vibrant and uniquely animated volumetric fire that supports bi-directional environmental macro-level interactivity. Our system is easily customizable by content artists. The fire is animated both on the macro and micro levels. Macro changes are controlled either by a prescripted sequence of movements, or by a realistic particle simulation that takes into account movement, wind, high-energy particle dispersion and thermal buoyancy. Micro fire effects such as individual flame shape, location, and flicker are generated in a pixel shader using three- to four-dimensional Improved Perlin Noise or M-Noise (depending on hardware limitations and performance requirements). Our method supports efficient collision detection, which, when combined with a sufficiently intelligent particle simulation, enables real-time bi-directional interaction between the fire and its environment. The result is a three-dimensional procedural fire that is easily designed and animated by content artists, supports dynamic interaction, and can be rendered in real time.