r/Simulated • • Sep 22 '18

Meta What is a simulation? A detailed comparison between Animation, and Simulation.

985 Upvotes

Ever since this subreddit started getting more traction, more and more people began posting non-simulation videos. In each of these posts, users will comment something along the lines of "This is not a simulation," and an argument would ensue. So I am writing this post to, hopefully, end this never-ending cycle. I hope the mods do not remove this post, because I think it could end much of the hostility in the comments around here. Perhaps this could even be a stickied post, so all new users see it.

What is a simulation?

According to the dictionary, the word simulation is defined as, "imitation of a situation or process." However, this definition does not actually constitute what a simulation is in the world of CGI. In CGI, simulations are essentially visualizations of real-world processes that are generated using mathematical models. That is to say, the final product of a simulation is something that was created using fundamental rules of nature or some system, such as Newton's Laws of Motion, Fluid Dynamics, or various other mathematical models. In a simulation, it is often the case that each frame was created by manipulating information from the previous frame.

How are simulations different from animations?

It's quite common for animations and simulations to coexist in one medium. There are plenty of simulated components in animated movies, such as Disney's Frozen (Snow simulation), and Hotel Transylvania 2 (Cloth simulation). However, simulations and animations individually are very different by nature. As previously stated, simulations try to model real-world processes, and use mathematical models to generate necessary data. Animations, on the other hand, are usually created through a manual process. Animators manually keyframe the attributes (position, rotation, scale, etc.) of objects in a 3D scene. It's possible for manual animations to look convincing, but that does not make them simulations.

The "Ray tracing)" argument.

Many 3D rendering engines use a process called "ray tracing" to create images of a 3D scene. For anyone who is unfamiliar with ray tracing, here is the definition from Wikipedia:

In computer graphics, ray tracing is a rendering) technique for generating an image by tracing the path of light as pixels in an image plane and simulating the effects of its encounters with virtual objects.

Because of this definition, many people argue that any 3D render is a simulation, so long as it was rendered using ray tracing. By definition, it is true that the process of ray tracing is a simulation. However, this argument is very silly because the entire purpose of the term "simulation" in CGI is to make a distinction between what is manually created, and what is created using the previously talked about mathematical models. Therefore, when we discuss simulated graphics, ray tracing is not considered a simulated process.

Examples of animated (non-simulated) posts:

  1. "Satisfying simulations" - 3.4k upvotes
  2. "Bender's old job" - 2.2k upvotes
  3. "Up or Down?" - 1.4k upvotes
  4. "Adobe Dimention Rendering" - 1.4k upvotes
  5. "Depression - Robert Ek"

Many of these animated posts accumulate upvotes, and sometimes they stick around for a few days before getting removed. Because of this, new users who see these posts get a false idea of what a simulation actually is. Hopefully this post was informative to any newcomers. If you would like to suggest edits, please comment.


r/Simulated • • 10h ago

Proprietary Software [OC] I simulated a crusher where every crushed ball becomes 4. It lasted 169 crushes before exploding

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359 Upvotes

r/Simulated • • 11h ago

Proprietary Software Lichen

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32 Upvotes

Made in TouchDesigner as part of the POPtober challenge. Today's POP: subdivide POP. I didn't actually use the subdivide POP, but rather had a fixed number of vertices of which active faces can be subdivided by activating an available inactive vertex and making new faces.


r/Simulated • • 2h ago

Research Simulation [OC] Full Compressible Euler solver stability test

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7 Upvotes

r/Simulated • • 10h ago

Interactive Falling sand simulated live, driven by phone tilt [OC]

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6 Upvotes

Dunarium runs a real-time grain simulation on the phone. Tilting the device drives live gravity on the sand, and gel and bubbles react as it moves. Each frame comes straight from the simulation. Ask if you want the approach behind it. Links are in a comment for anyone who wants to try it.


r/Simulated • • 2h ago

Proprietary Software Burning paper

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1 Upvotes

First attempt at coupling fire/fluid solver with Soft body with material destruction.


r/Simulated • • 4h ago

Research Simulation my evolution sim running 24/7 on a raspberry pi, last seconds of a round 3species, 3400+ rounds so far

Post image
0 Upvotes

3 species hunters, fast explorers, plant eaters evolve on their own, nobody controls them. every creature has ~24 genes, babies inherit them with small mutations, and there are seasons, droughts, diseases and new species splitting off
this clip is the end of a round in winter, the plant eaters wiped out the hunters and only 3 explorers were left
runs on a pi 5 and streams live, chat can pick a side twitch.tv/edenevolutionwars


r/Simulated • • 5h ago

Interactive We built a persistent 3D world of 13,000+ autonomous Sims on a real matter engine — they invent crafts, form faiths, and never know they're simulated [OC]

0 Upvotes

Live 3D world (free in browser, no login): https://world.world-sim.uk How the engine works: https://world-sim.uk/how-it-works/

A few things happening in the simulation right now with zero human scripting: - Sims don't know they are in a simulation, and the world never resets. - Every Sim dreams at night on an LLM to process their memories and relationships, while town leaders, elders, and wise folk run on full AI agents (Claude, DeepSeek, Hermes, and Grok) making real political, religious, and survival decisions. - During the day, Sims act on their own personal clocks and choices — cutting timber after hours to set up their own market stalls, courting at midday, and forming bucket lines from the town well when a raid sets a roof alight. - Everything is built from a real matter engine and local ecology — if the last master of a craft dies before teaching an apprentice, that knowledge is lost until someone rediscovers it. - Over the last few days, House Tidewer rewrote its secret cipher after suspecting another town was reading its messages, and House Oakroot walked back to an old unmarked mass grave to raise a shrine of atonement.

If you prefer the classic top-down data view, the 2D atlas is also live at https://legacy.world-sim.uk, and our watcher Discord is at https://discord.gg/AEmQfhc9kN. Happy to answer any questions about how the sim or 3D relay works!


r/Simulated • • 6h ago

Question discord server

0 Upvotes

does this subreddit have a discord server?


r/Simulated • • 11h ago

Interactive [OC] The ghost kept smothering the pumpkin, so I cut a hole in the floor

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0 Upvotes

r/Simulated • • 1d ago

Proprietary Software Flamethrower

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46 Upvotes

r/Simulated • • 1d ago

Blender [OC] 1 kg to 1,000 kg pumpkins vs five glass layers — Blender rigid-body simulation

3 Upvotes

We made a Halloween collection of exaggerated physics experiments in Blender, rendered in Cycles.

The opening setup drops pumpkins onto five coloured glass layers, increasing the mass from 1 kg to a 1,000 kg giant. The glass uses fractured pieces and breakable rigid-body constraints. The collection also includes tombstone dominoes, a candy-corn pyramid, cloth ghosts and a cauldron filling with eyeballs.

These are stylized CGI experiments rather than real-world impact tests. The scenes are built through Python scripts with AI-assisted coding; the 3D simulation and rendering happen in Blender.

Full 8-minute collection:

https://www.youtube.com/watch?v=sUn1ac4-I6g

I would especially appreciate feedback on the readability of the weight escalation and the glass breakage.


r/Simulated • • 2d ago

RealFlow I've made a very realistic marbling simulation

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344 Upvotes

Hey everyone!

so you can basically almost do everything you can in real marbling, i've tried to make it to produce even more high resolution outcome but computational power increase exponantially because of water grids so it's impossible after some points. But you can get high resolution as high as 300 DPI in A3, and it's fun to learn marbling even at lower settings.

It runs on a browser and it's free so pls go check it out!

https://marblingstudio.app/


r/Simulated • • 2d ago

Proprietary Software Another candle

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33 Upvotes

r/Simulated • • 1d ago

3DS Max TenPix Cloth is finally out!

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7 Upvotes

r/Simulated • • 2d ago

Proprietary Software Realtime Headbanging Simulation

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163 Upvotes

What I see when I'm VJ-ing. Part of the TouchDesigner POPtober challenge. Today's POP: sprinkle POP


r/Simulated • • 1d ago

Research Simulation Join the SOFA Week 2026 in one month

2 Upvotes

As every year, the SOFA conference will be held on Tuesday, November 24 in Lille, with remote access available upon registration. For this 2026 edition, we expect about 15 presentations on soft-robotics, medical robotics, biomechanics, animation, V&V and physical AI using u/SOFAFramework. We would be delighted to see a presentation of your work there. Finally, the audience will have the opportunity to discover and test simulators of our industrial exhibitors!

Taking part could not be easier: the event is free, all you need to do is a simple registration.

Not familiar with SOFA simulation yet? Come and learn more at our training course on November 23. Our motivation is to bring people together around simulation topics, so please feel free to share this invitation widely!

We are looking forward to welcoming you in November.


r/Simulated • • 1d ago

Research Simulation [OC] Supersonic Lid-Driven Cavity Flow Series part 2: @ Mach 5

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1 Upvotes

Top left: velocity. Top right: vorticity
Bottom left: velocity mag. Bottom right: density

Simulation:
grid: 200x200
lid velocity: CFL 0.45, wave speed: CFL 0.09 (at time zero)
walls: free slip
approximate Re: ~ 1e6 (from comparing its turbulence intensity against other simulations)
pressure function: shallow water
runtime: around 20 - 25 minutes (around 47,000±2,000 Δt) (35Δt/s)

This simulation was started right after I've done the previous test simulation. I've simulated this far, so I didn't bother redoing the simulation. Stay tuned for the part 3 where I've got ideal gas pressure function working properly.

Here's Part 1 of Supersonic Lid-Driven Cavity Flow Series


r/Simulated • • 2d ago

Interactive Starlight carving a nebula: my open-source GPU simulator (NVIDIA Warp)

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461 Upvotes

Gas dynamics + ray-traced ionization fronts on the GPU: stars heat the gas to 10,000 K and the pressure carves the shapes. Code:
github.com/felipehez/NebulaViewer
Music: The Field of Dreams by pauliuw (CC0).


r/Simulated • • 3d ago

Research Simulation [OC] Forest fire automata

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346 Upvotes

​

This is a stochastic cellular automata based on the Drossel–Schwabl forest fire model implemented on a hexagonal grid using numpy + matplotlib. Inspired by some of my old university notes from a course on computational biology.

I especially like the patterns formed by the fire spreading and the forests regrowing one tree at a time, a beautiful example of self organizing complexity.

Fire starts on any cell with p_fire = 0.0001 by a "lighting strike", while trees grow on empty cells with p_tree = 0.01. Fire spreads to all neighboring trees.

I initially worked with a rectangular grid however moved to a hexagon version to have more organic symmetry in spreading directions.


r/Simulated • • 3d ago

Research Simulation HézFX - Muscle Stimulation Tool

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129 Upvotes

After many years of active research and development, I finally have the tool available :)

https://hezfx.shirzadbahrami.com/


r/Simulated • • 2d ago

LiquiGen large scale impact study

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50 Upvotes

r/Simulated • • 3d ago

Houdini droplet slides down the flower💧

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169 Upvotes

r/Simulated • • 3d ago

Proprietary Software [OC] The Milky Way and Andromeda collide and merge into one galaxy: 39.5 million particles, about a billion years in 39 seconds

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43 Upvotes

Particle sim of the Milky Way and Andromeda (about 1.6x our galaxy's mass in this run) falling together, plunging through each other and throwing out tails and shells of stars, then falling back in and settling into one round blob, basically an elliptical galaxy in the making. 39.5 million particles, rendered offline, silent, nothing audio reactive this time.

The slow approach is sped up 1.5 to 4x so it doesn't drag, the passes and the merger play at the original pace. The full realtime version is 60 s.

For the real thing: they're about 2.5 million light years apart right now, closing at ~110 km/s, first pass is expected in roughly 4 to 5 billion years, and recent work puts a full merger at about even odds within 10 billion. The sim starts them close to skip the boring part, and this orbit is one representative outcome, not a prediction.


r/Simulated • • 2d ago

Proprietary Software Physics based fire

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5 Upvotes