r/Simulated • • Sep 22 '18

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

988 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 • • 5h ago

Proprietary Software New look for the simulated snow in my snowplow prototype

89 Upvotes

New look for the snow: instead of round beads it is now drawn as small blocks, each turned and shaped a little differently, and lit by the shape of the drift they lie in. Loose snow tumbles, packed tracks stay smooth (early prototype)


r/Simulated • • 31m ago

Blender [OC] Honey pouring off a spoon onto a dipper, simulated in Blender

11 Upvotes

r/Simulated • • 5h ago

Blender Hey everyone! I've been working on my custom Blender add-on, Blob Matter, for over a year now.This is an extreme stress test with 120,000 fractured pieces—fractured in just 27 seconds using my custom fracture, RBD physics, and smoke backend. Even at this massive scale, the simulation solves at 1–7

11 Upvotes

Hey everyone! I've been working on my custom Blender add-on, Blob Matter, for over a year now.

This is an extreme stress test with 120,000 fractured pieces-fractured in just 27 seconds using my custom fracture, RBD physics, and smoke backend. Even at this massive scale, the simulation solves at 1–7 FPS (while standard piece counts run significantly faster), and once cached, playback is buttery smooth in real-time right inside the viewport.

The add-on is designed for both fast workflows and complex, non-destructive setups, featuring both a standard UI panel and a fully-integrated node system.

Happy to answer any technical questions about the engine or the pipeline!


r/Simulated • • 20h ago

Meta We got cloth physics in Desmos before GTA6

149 Upvotes

r/Simulated • • 2h ago

Houdini Divine Machinery (smoke sim)

5 Upvotes

r/Simulated • • 3h ago

Research Simulation NeuroSnake: CTRNN Lifeform for Garmin

4 Upvotes

Hey everyone,

After building two watch faces with a real C. elegans connectome, I evolved a 9-neuron digital snake from scratch for Garmin

Some time ago, I made two experimental Garmin watch faces (NeuroWorm Quantum and NeuroWorm Fluid) based on the real biological connectome of Caenorhabditis elegans — the tiny worm that spent around 100 million years evolving its 302 neurons.

After playing with real biology, I got curious about the opposite approach: what if I compress millions of years of evolution into a few days of multi-threaded simulation on my PC, and grow a tiny brain from scratch specifically to live on a smartwatch?

So I built NeuroSnake: Evolved Lifeform as a spin-off to that series.

How it actually works (no fake AI):

  • Zero hardcoded behavior: There is no pathfinding, no if-else rules, and no scripted logic telling the snake where to turn. Everything it does comes from a continuous-time recurrent neural network (CTRNN) forged through 10 million simulated lifetimes.

  • Tiny brain, real constraints: Smartwatches have very limited CPU and RAM (especially older devices and monochrome Instinct models), so I had to keep it super compact. Right now, its entire brain is just 9 evolved interneurons and 30 synapses connecting its sensory rays to its muscles. My simulation is still running on my PC,so future updates might give it a few more hard-earned neurons.

  • It adapts to you: Once it hatches on your watch, real-time Hebbian plasticity kicks in. Your daily steps charge the energy pool that spawns food capsules and sends ripples across the screen. After a few days on your wrist, the synaptic weights slowly tune to your personal movement rhythm - so your snake becomes uniquely yours.

  • Don't feel bad when it dies: Sometimes it crashes into the clock digits or a fluttering anomaly. That’s just evolution doing its thing - the same process that built you, me, and this little digital creature.

I got a lot of inspiration from the scientists who spent decades mapping C. elegans, as well as the recent breakthroughs in mapping and simulating the fruit fly (Drosophila) brain. Honestly, I just feel huge gratitude to all the curious people throughout human history who kept digging into how nature works.

WatchFace is on review process for Garmin Connect IQ store as it will be approved I will add a link in the comments below (supports both AMOLED/MIP color watches and monochrome Instincts).

Happy to answer any questions about the neural net, the training process, or squeezing Monkey C performance on Garmin hardware!

(Note: English isn’t my native language, so I used an AI assistant to help me clean up this post and the store description, though I’m good enough with English to answer any questions in the comments!)


r/Simulated • • 19m ago

Various oddly satisfying

0 Upvotes

r/Simulated • • 1d ago

Houdini houdini create ocean wave effect

107 Upvotes

r/Simulated • • 4h ago

Blender Sydney Opera House earthquake destruction simulation in Blender

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0 Upvotes

r/Simulated • • 1d ago

Interactive Strata - [OC] - solo dev cute layered universe simulation game (no gen AI)

6 Upvotes

Fingers crossed I dont get banned into oblivions for this 😄

I'm dropping short clip form my upcoming game Strata - an early gameplay of a persistent open world where pretty much everything is real time simulated.

Thanks for viewing and the feedbacks!


r/Simulated • • 1d ago

Blender Have you tried this ?

0 Upvotes

@shipstack__ on instagram they have pretty cool physics animation


r/Simulated • • 2d ago

Research Simulation Artificial life simulation showing evolved creatures

132 Upvotes

Made with the open-source artificial life simulator ALIEN 5.0-beta: https://github.com/chrxh/alien

YouTube: https://youtu.be/Vxo0vdiDTTo


r/Simulated • • 3d ago

Proprietary Software GPU accelerated "Powder Toy"-like simulator demo

71 Upvotes

I made it using JS and WebGPU. It runs in the browser and can easily manage 240 FPS with a 1920x1080 grid on an RTX 5080, only dropping to 200 fps when you fill the entire grid with water. All this extra performance headroom allows for much more realistic fluid simulation, fire, and post processing effects. The water still needs some tweaking, too viscous, but it's a start. Not sure if I'll continue working on it, but it was a fun experiment nonetheless.


r/Simulated • • 2d ago

Proprietary Software Macrozoa

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1 Upvotes

Hey everyone. I'm working on a microorganism simulation app where you can design your own creatures from cell to cell, teach them survival skills, and observe them in their virtual petri dish, which you can also build yourself. I started a video series to document the progress. If you like soft-body physics simulations, reinforcement learning, and artificial life experiments, take a look and follow the progress.


r/Simulated • • 3d ago

Research Simulation Flow field and pressures

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13 Upvotes

I'm learning the most basic simulation softwares from an environmental engineering course. This is the first time I ever simulated something.

It is supposed to be the steady state impact of an atmospheric flow on some vary unoriginal structures. The scope of later simulations will be to numerically reproduce so called urban canyons, a phenomenon in which - to my understanding - large vortexes are created in between buildings based on their heights and distances.

This first simulation was made to show us the softwares and setting up the parameters of what we had until now written and learned but never properly seen. In my ignorance, being only a student and having never done anything like this, I am amazed by it so I thought of posting it.

What I particularly like is that while playing with the thing I noticed that I could isolate an axis for the flow field. When isolating Y (vertical direction) I could recognize one of those dislocated vortexes I was always shown on images. Very cool stuff.

With your experience it would be nice to know what you would think of something so primitive.

I'm not sure about the flair, I didn't know which one to add


r/Simulated • • 1d ago

Houdini FUCK YOU

0 Upvotes

r/Simulated • • 3d ago

Research Simulation [OC] Supersonic Lid-Driven Cavity Flow Series part 4: Re > 1,000,000 ILES at 2km/s (Mach 5.76) and at 4km/s (Mach 11.52).

9 Upvotes

Simulation #1:
grid: 200x200
pressure function: ideal gas
initial condition: 27°C atmospheric air (γ = 1.4)
lid velocity: 2 km/s
runtime: 1 hours 30 minutes

Simulation #2:
grid: 200x200
pressure function: ideal gas
initial condition: 27°C atmospheric air (γ = 1.4)
lid velocity: 4 km/s
runtime: 1 hours 38 minutes

ㅤ

From what I see, their differences are in the initial stage. After that, they look pretty similar due to heating effect so I stopped the simulation since there's nothing new after that. The previous run was longer - to the point it nearly converges to typical high Re lid driven cavity flow.

In the part 2, it keeps the distinct characteristic for the rest of the simulation due to the lack of temperature effect as I was using isentropic (shallow water) pressure function. (the lid boundary condition was wrong in that simulation, but I can see what it'll look like with the correct BC.)

Next time I might do Mach ∞ run to see how long it converge to low Mach state.

Supersonic Lid-Driven Cavity Flow Series: previous next


r/Simulated • • 4d ago

Interactive Failing to save Earth from getting hit by Mars – 6 different ways

97 Upvotes

Screen capture from Planets in a Box, a planetary physics sandbox on Steam.
Recording sped up 2x.

About 1-2 million particles. SPH with Barnes-Hut gravity and a simplified equation of state for iron and silicate.

https://store.steampowered.com/app/5411970/Planets_in_a_Box/


r/Simulated • • 4d ago

Various I added an enemy that regenerates skin, muscle and bone from taken damage in my voxel physics game

200 Upvotes

r/Simulated • • 4d ago

Research Simulation [OC] I trained a six-legged robot to walk with reinforcement learning. It runs in real time in your browser, and you can throw a 171 kg steel ball at it.

9 Upvotes

Real-time MuJoCo physics, no keyframes. The walk and the recoveries come from a policy trained with reinforcement learning, and everything runs in your browser (MuJoCo WebAssembly, ONNX Runtime Web, three.js).

Try it yourself: https://www.coolspeed.org/gold-spider/

Setup details in the comments.


r/Simulated • • 4d ago

Houdini Along curves move

23 Upvotes

r/Simulated • • 5d ago

Research Simulation Muscle simulation tool I've been developing is finally out

692 Upvotes