Houdini is a 3D animation software application developed by Toronto-based SideFX, who adapted it from the PRISMS suite of procedural generation software tools. The procedural tools are used to produce different effects such as complex reflections, animations and particles system. Some of its procedural features have been in existence since 1987. Houdini is most commonly used for the creation of visual effects in film and television. It is used by major VFX companies such as Walt Disney Animation Studios, Pixar, DreamWorks Animation, Double Negative, ILM, MPC, Framestore, Sony Pictures Imageworks, Scanline VFX, Method Studios and The Mill. It has been used in many feature animation productions, including Disney's feature films Fantasia 2000, Frozen, Zootopia and Raya and the Last Dragon; the Blue Sky Studios film Rio, and DNA Productions' Ant Bully. SideFX also publishes Houdini Apprentice, a limited version of the software that is free of charge for non-commercial use. Release history Features Houdini covers all the major areas of 3D production, including these: Modeling – All standard geometry entities including Polygons, (Hierarchical) NURBS/Bézier Curves/Patches & Trims, Metaballs Animation – Keyframed animation and raw channel manipulation (CHOPs), motion capture support Particles Dynamics – Rigid Body Dynamics, Fluid Dynamics, Wire Dynamics, Cloth Simulation, Crowd simulation. Lighting – node-based shader authoring, lighting and re-lighting in an IPR viewer Rendering – Houdini ships with SideFX's rendering engines Mantra and Karma; Houdini Indie licence and up support 3rd party rendering engines, such as Renderman, Octane, Arnold, Redshift, V-ray, Maxwell(soon). Volumetrics – With its native CloudFx and PyroFx toolsets, Houdini can create clouds, smoke and fire simulations. Compositing – full compositor of floating-point deep (layered) images. Plugin Development – development libraries for user extensibility. Houdini is an open environment and supports a variety of scripting APIs. Python is increasingly the scripting language of choice for the package, and is intended to substitute its original C Shell-like scripting language, HScript. However, any major scripting languages which support socket communication can interface with Houdini. Tools Operators Houdini's procedural nature is found in its operators. Digital assets are generally constructed by connecting sequences of operators (or OPs). This proceduralism has several advantages: it allows users to construct highly detailed geometric or organic objects in comparatively very few steps; it enables and encourages non-linear development; and new operators can be created in terms of existing operators, a flexible alternative to non-procedural scripting often relied on in other packages for