showstack

The first one

Dataflow: why a patch is not a script

Open Max, Pure Data, TouchDesigner, vvvv, Notch or Unreal's Blueprints and you get boxes joined by wires. The instinct is to read it as a flowchart — do this, then this. That is the wrong model and it makes everything harder.

It is a patch bay. Each box is a device that is permanently powered on. Each wire is a cable. Nothing is "called" and there is no beginning: the whole graph is live, and data moves through it continuously. You are not writing a sequence of instructions, you are building an instrument and then playing it.

That is exactly why this style caught on in this industry rather than in general software. Anybody who has patched a rack already holds the mental model. The signal-flow intuition transfers directly, and so does the debugging habit: when it is wrong, you probe along the chain until you find where the signal stopped looking right.

The families

What each dataflow tool is actually for

Max/MSP (Cycling '74) is three layers with one look. Max is the message layer — control-rate events, the things that happen when something changes. MSP is the audio layer, where objects whose names end in a tilde process a continuous signal at sample rate. Jitter is the matrix layer, for video and data grids. Being able to move between an event and a sample-rate signal in one patch is what Max is for, and it is why it stayed the standard in music technology and interactive installation. Max for Live puts the same environment inside Ableton Live.

Pure Data is the open-source ancestor of the same idea, by the same author, and it is the pragmatic choice when a piece has to keep running for years without a licence server in the way.

TouchDesigner is the same model built on the GPU, and it organises everything into operator families you connect together: TOPs are textures, CHOPs are channels of numbers over time, SOPs are geometry, DATs are text and tables, MATs are materials, COMPs are containers. Python is embedded throughout, so the awkward parts do not have to be patched. It has become a default for interactive and generative content, and for wiring a protocol into a picture.

Notch is a real-time VFX tool whose output is a block that runs live inside a media server — disguise, Hippotizer, PIXERA — with its parameters exposed to the operator. That is its whole point: effects that stay adjustable on site instead of being baked into a file at the last render.

vvvv and Blueprints complete the picture — vvvv as a long-standing patching environment for installation work, Blueprints as Unreal's visual layer over the same engine its C++ reaches.

The second one

What a game engine actually is

Unreal, Unity and Godot are usually described as tools for making games. That is a market, not a definition. What they actually are is real-time renderers with everything attached: a scene graph that holds a world, a physics simulation, an asset pipeline, an animation system, a scripting layer, and a renderer whose job is to produce a complete new frame in the time before the display needs one.

The consequence is the whole reason they arrived in this industry. A video file is a sequence of frames someone computed in the past. It is beautiful, it is exactly as intended, and it cannot answer a question. A real-time engine holds the scene — geometry, materials, lights, cameras — and draws it now. So it can be asked something: where is the camera, where is the performer, what did the operator just change, what is the tracking system reporting this millisecond.

That is what makes an LED volume possible, what makes previsualisation useful rather than decorative, and what lets an AR graphic sit convincingly on a pitch. Not the rendering quality — the timing of the rendering.

Spend the budget and watch it run out

The three

Unreal, Unity and Godot

The practical part

How a scene actually becomes something an audience sees

The workflow is the same in all three, and it is worth knowing the shape even if someone else does it.

Build the world. Geometry comes in from a modelling tool — Blender, Cinema 4D, Rhino — or from a scan. Materials describe how each surface responds to light. Lights and cameras are placed. At this point you have a place, not a picture.

Animate it. Keyframes on a timeline for anything choreographed; simulation for anything that should behave rather than be posed; and, on a show, live input for anything that has to follow reality.

Then choose when it is drawn. This is the decision that matters. Render it offline — Unreal's Movie Render Queue, or the equivalent — and you get a file: maximum quality, fully deterministic, and completely fixed. Or run it live, and you get responsiveness at the cost of a hard per-frame budget. Plenty of shows do both: pre-rendered content for the sections that are locked, a live engine for the sections that must follow a camera or a performer.

Where it joins the show

The engine is just another device on the network

A render engine on a show is not an island. It takes the same signals as everything else, which is the entire subject of this site.

In: Art-Net or sACN so an operator can drive virtual fixtures — or drive the real rig from the same cue that moves the content; FreeD for camera position and lens; PSN or RTTrPM for performer tracking; LTC or PTP so it agrees with everyone else about time; OSC for everything else.

Out: video over NDI or ST 2110, or a vendor stream into a media server, or straight to an LED processor with genlock holding the frames together.

This is also how previsualisation works. Capture, WYSIWYG, Depence, Vision and Realizzer are real-time engines with a lighting-specific asset library: the console sends real DMX, the engine renders what those fixtures would do, and a designer programs a show in a room that does not exist yet. Same machinery, aimed at a different question.

Where to start

If you want to learn one of these

For content and interaction, start with TouchDesigner. It is the shortest distance between a protocol arriving on a network port and something moving on a screen, and the free non-commercial licence is genuinely usable for learning.

For sound and event logic, start with Max, or Pure Data if you want it free and permanent. The tilde/no-tilde split is the concept to get straight on day one.

For 3D worlds, start with Godot if you want to understand engines, or Unreal if you want to work in virtual production, because that is where the industry tooling is.

And in every case the transferable part is not the software. It is knowing what signal you are taking in, what promise you are making about the next frame, and which clock you are reading — which is the rest of this section.