Fumaris: Fire for the Festive Blender Brief

For those who don’t know the tool: Fumaris by Michael Venous of Venous FX brings GPU smoke and fire simulation into Blender. It combines an interactive volume preview with OpenVDB output for final volume shading and rendering.

Season’s greetings, with combustion

After a difficult year, perhaps the seasonal greetings film needs a candle igniting the Christmas tree, timed just right. A tiny flame, a thoughtful pause, then the spruce makes an ambitious career move into smoke. In Blender, naturally. The festive brief is getting the escalation just right without waiting for a fresh bake after every adjustment.

Fumaris lets artists change emitters, wind and combustion settings while its GPU preview runs. The current 1.3.1 release adds persistent GPU selection, timeline-linked simulation ranges, cache protection and new preview lighting. Those are useful refinements when the client wants the tree a little less apocalyptic, but would still like to feel the year.

Give the flame something to work with

The Blender integration sends scene inputs to a separate native runtime using NVIDIA Flow through Vulkan; the Apple Silicon package uses Metal through bundled MoltenVK. One object holds the simulation settings, while collections identify emitters, colliders, effectors and outflows. The domain object’s dimensions do not form a fixed smoke box: Flow allocates a sparse grid around active smoke.

Quick Setup supplies Rising Smoke, Steady Fire and Explosion starting points. Sources can include meshes, particles, Geometry Nodes points and OpenVDB volumes. Named point attributes control radius, velocity, smoke, temperature, fuel, burn, divergence, coupling and masks. Wind, vortex and turbulence effectors shape the motion; outflows remove smoke and combustion channels.

The manual also describes per-channel Blend, Add, Maximum and Replace source operations. Maximum can raise temperature without cooling an already hotter region, a useful distinction when art-directing ignition. For the Christmas-tree shot, that means designing the sources and their timing as carefully as the plume.

Keep the take, spare the argument in Fumaris

The preview raymarches the volume on the GPU. Artists can pause, orbit the result and adjust appearance before resuming. Enable Bake on Preview before playback to record OpenVDB frames at preview resolution; recording adds export work. A regular final Bake starts a separate simulation and writes the full sequence. It does not retrospectively preserve that lovely preview you forgot to record.

Version 1.3.1 makes iteration safer: New Slot selects an unused versioned cache slot, Protect blocks baking or deletion in a locked slot, and overwrite/delete actions request confirmation. Use Timeline follows the scene range with optional warmup. The GPU selector stores a device UUID, so a changed device order does not silently send the job to another card; switching requires stopping the active job.

Flame Light adds warm illumination from fire into nearby smoke, while Light Scattering fills shadowed billows. Both affect the interactive preview only. Final OpenVDB materials and lighting remain separate. Our earlier NeXus for Blender coverage explores another GPU simulation workflow for artists weighing their options.

Availability and the final bake

Fumaris is available through Superhive, currently listing US$39, and Gumroad. It requires Blender 5.2 or newer. Windows and Linux need a Vulkan-capable GPU with a current driver; Linux also requires glibc 2.35+. Apple Silicon requires macOS 26+. The Python integration is GPL-3.0-or-later, while the native runtime and bundled components have separate licences. The developer’s licence overview permits personal and commercial artwork; input-asset rights still apply.

Check the intended shot before committing: performance depends on hardware and settings, AMD GPUs remain unqualified, and Intel Macs are unsupported. Preview lighting differs from final rendering; experimental Geometry Nodes volume emission and thin colliders need particular care. A stopped bake keeps completed frames but cannot resume solver state. Get the timing into a checked cache, then send the seasonal greetings. After this year, even the fictional tree deserves an approved final version.