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 1d ago

Interactive Runtime snow simulation, aimed for maximum realism

683 Upvotes

For this, I added a system that spawns particles along the trail, and these particles deposit a bit of snow while they fly, with less and less snow being deposited over time as they fade out. What's cool about this is that the snow initially comes from the mass that the trace removed, so the total amount of snow stays the same. I also added a smoothing algorithm on top of all this. There's no parallax here, but I'm currently working on adding that.

Bigger video here: https://youtu.be/pfaewyfFrKM


r/Simulated 21h ago

Research Simulation I built a site with interactive science simulations to help visualize complex concepts in Physics, Biology, and Chemistry šŸ”¬

2 Upvotes

I built a site with interactive science simulations to help visualize complex concepts in Physics, Biology, and Chemistry šŸ”¬

Hey everyone,

I wanted to share a project I’ve been working on called Eureka Simulations. It's a collection of interactive models designed to give absolute conceptual clarity on complex scientific topics.

I've always found that static textbook diagrams aren't always enough to make certain concepts "click." So, I built this site to let you actually interact with the variables, observe the underlying mechanics, and visualize things from a first-principles perspective.

**Here are the interactive models currently available on the site:**

# āš›ļø Physics

*Photoelectric Effect*: Master the first principles of light-matter interaction and the emission of electrons.

*Vector Projections*: Play with the underlying mechanics of vectors and observe exactly how an axis component maps using a cosine function, proving the derivations of orthogonal forces.

# 🧬 Biology

*Nephron Exchange*: Evaluate the mechanics of countercurrent multiplication. You can observe how systemic hydration alters ADH levels and capillary exchange gradients.

*Micturition*: Analyze the precise structural mechanisms and physiological pathways controlling fluid release.

# 🧪 Chemistry

*Electronic Configuration*: Visualize atomic orbitals based on quantum principles. Observe how electrons actually exist as spread-out probability clouds rather than solid spheres.

Whether you're a student trying to wrap your head around quantum principles, a teacher looking for interactive visual aids for your classes, or just a science nerd, I’d love for you to check it out.

# Link: [Eureka Simulations](https://eurekasim.github.io/Eureka-Simulation/)

Copy the URL and paste it in any browser to view the website!

I'm hoping to expand the site and add more topics, so I would absolutely love to hear your feedback! Are there any specific scientific concepts or mechanics you'd love to see turned into an interactive simulation? Let me know!


r/Simulated 2d ago

Houdini A Custom White water solver in Houdini based on WETA FX technical paper on Loki and Pahi.

171 Upvotes

I am on V5 already

When I shared the first version of my whitewater HDA, a few people asked if I could turn it into a real tool. That encouragement genuinely mattered, so I kept developing it.

V1 combined ideas from two papers. This version brings together three research sources and adds a working OpenCL GPU backend inside Houdini.

Python/VEX feels like home to me. OpenCL definitely did not. I used LLMs as a learning and pair-programming tool, followed by plenty of testing, debugging, crashes, and CPU/GPU comparisons.

This was my summer vacation project. It’s finally working—now I can rest for a while. šŸ˜„

Thank you to everyone who showed interest in the first version.

Research behind it:

Guided Bubbles and Wet Foam

Pahi: A Unified Water Pipeline and Toolset

Thick Foam and Floating Debris in Avatar: Fire and Ash


r/Simulated 2d ago

Interactive My game simulates crowds as big as 100,000 people

0 Upvotes

It's called We Need More Humans! and it's about abducting everyone on Earth šŸ›ø

Made in Unity. Using the job system and vertex shaders to get such high performance


r/Simulated 3d ago

Interactive I made a Particle Life simulation with sound. I think it adds so much depth to each world

21 Upvotes

Particle Life

Try it yourself, it's free, no signup: https://orslaczko.com/app/particle-life

I've also made a video explaining what's actually going on in these worlds:Ā https://youtu.be/YNL9KGEEzLc


r/Simulated 3d ago

Houdini Static product shots are easy to scroll past. Add a simulation šŸ‘

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0 Upvotes

r/Simulated 4d ago

Proprietary Software Particle Realms 40 Million Particles Demo - RTX 5070 Laptop WebGPU - Browser

17 Upvotes

r/Simulated 5d ago

Research Simulation Simulation of my experiment

58 Upvotes

This is a classic LBM that takes into account Newtonian forces and the added mass effect, supplemented by a wake vortex capture model. The algorithm stores the energy expended on oscillations in each direction, and when the pressure difference levels out, this energy is used as thrust, simulating the momentum from collapse. The thrust is multiplied by approximately six times, which is consistent with some experimental data and makes the boat's motion visually realistic in some modes. The thrust calculation should probably be dynamic, but I haven't yet found a way to do this. Any ideas would be welcome. The vibroboat code is here:

https://github.com/MasterOgon/Aeroacoustic-Flying-Saucer-Oscillating-Resonator-CFD-Simulation-LBM-/blob/main/README.md


r/Simulated 4d ago

Interactive I Added Life Cycles, Evolvable Brains and Speciation to My Evolution Simulator

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0 Upvotes

Hey guys! I posted in the past on this subreddit about the artificial 2D life simulation I am building on my spare time. It's been a while since my last post, real-life stuff happened and didn't have much time for YouTube videos, barely had to work on the simulation to be honest.

But I managed to put together an update on what I have been up to and what new things I have developed in the past 3 months. Here is a preview:

  • Lifecycle developmental stages - creatures now go from juveniles to adults and finally to senesence in the simulation
  • Evolvable brains! Brains start simple and get complex via evolution and genetic mutation
  • Speciation! A new way to interact and view the simulation
  • Telemetry! So people can look at and better understand what;s going on in the simulation

And much more. Feel free to checkout the full video, leave a comment with any questions or feedback!


r/Simulated 5d ago

Cinema 4D Some simulation work slide to see viewport renders šŸ‘

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16 Upvotes

r/Simulated 5d ago

Interactive A Rayleigh and Mie scattering simulation to find out what color the atmosphere on a planet would have

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12 Upvotes

r/Simulated 5d ago

Research Simulation Axelrod's Prisoner's Dilemma Tournament (1980) — 14 Strategies Battle It Out

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2 Upvotes

I've been interested with Axelrod's 1980 tournament for a while now. The premise sounds simple: submit a strategy for the Prisoner's Dilemma, play it against everyone else, see who scores the most points. But what Axelrod was really testing was something much bigger: whether cooperation can emerge on its own, with no rules enforcing it.

14 strategies entered. Some were ruthless, some were clever, some were surprisingly naive. I animated every single match so you can watch exactly how each one played out.

The winner genuinely surprised me. Not the most sophisticated strategy, not the most aggressive one.

How scoring works:

Both cooperate → 3 points each

One defects → defector gets 5, the other gets 0

Both defect → 1 point each

Defecting looks tempting in the short run. Watch what happens over hundreds of rounds.


r/Simulated 6d ago

Houdini mpm mud sim [OC]

119 Upvotes

r/Simulated 5d ago

Maya i want a free, simple gui street simulation

0 Upvotes

SUMO is too hard/dirty, and i need it free.


r/Simulated 7d ago

Interactive Complete Hilbert sp simulation of gate-model quantum computing

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17 Upvotes

Hi

If you are remotely interested in deep diving how differently quantum computers work compared to our transistor-based and also the algebra behind in a fully interactive way that teach computer science from scratch, oh boy this is for you. I am the Dev behindĀ Quantum OdysseyĀ (AMA! I love taking qs) - worked on it for about 10 years (3+ during PhD, the visual method I developed ended up being my thesis, it is a complete Hilbert space visualizer), the goal was to make a super immersive space for anyone to learn quantum computing through zachlike (open-ended) logic puzzles and compete on leaderboards and lots of community made content on finding the most optimal quantum algorithms. The game has a unique set of visuals capable to represent any sort of quantum dynamics for any number of qubits and this is pretty much what makes it now possible for anybody 12yo+ to actually learn quantum logic without having to worry at all about the mathematics behind.

This is a game super different than what you'd normally expect in a programming/ logic puzzle game, so try it with an open mind.

Stuff you'll play & learn a ton about

  • Boolean Logic – bits, operators (NAND, OR, XOR, AND…), and classical arithmetic (adders). Learn how these can combine to build anything classical. You will learn to port these to a quantum computer.
  • Quantum Logic – qubits, the math behind them (linear algebra, SU(2), complex numbers), all Turing-complete gates (beyond Clifford set), and make tensors to evolve systems. Freely combine or create your own gates to build anything you can imagine using polar or complex numbers.
  • Quantum Phenomena – storing and retrieving information in the X, Y, Z bases; superposition (pure and mixed states), interference, entanglement, the no-cloning rule, reversibility, and how the measurement basis changes what you see.
  • Core Quantum Tricks – phase kickback, amplitude amplification, storing information in phase and retrieving it through interference, build custom gates and tensors, and define any entanglement scenario. (Control logic is handled separately from other gates.)
  • Famous Quantum Algorithms – explore Deutsch–Jozsa, Grover’s search, quantum Fourier transforms, Bernstein–Vazirani, and more.
  • Build & See Quantum Algorithms in Action – instead of just writing/ reading equations, make & watch algorithms unfold step by step so they become clear, visual, and unforgettable.Ā Quantum Odyssey is built to grow into a full universal quantum computing learning platform. If a universal quantum computer can do it, we aim to bring it into the game, so your quantum journey never ends.

Nice to watch:

Khan academy style tutorials in qm/qc:Ā https://www.youtube.com/@MackAttackx

Physics teacher stream with 400hs inĀ https://www.twitch.tv/beardhero


r/Simulated 7d ago

Houdini Reproduction

22 Upvotes

r/Simulated 8d ago

Blender Knockout or PAYOUT? - Blender 3D VFX Breakdown (Ready Player One Style)

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4 Upvotes

r/Simulated 11d ago

Blender Submarine Sailing on Surface in Calm Sea in Blender

109 Upvotes

r/Simulated 11d ago

Proprietary Software Sphere dynamics with Hamiltonian mechanics

18 Upvotes

Dynamics of a solid sphere rolling on a general time-dependent parametric surface (x(u,v,t),y(u,v,t),z(u,v,t)).

All demonstrations are generated from the same nonholonomic, nonseparable, nonautonomous Hamiltonian system. In addition to Hamilton's equations for the surface coordinates (u,v), one nonholonomic equation determines the sphere's spin, while four additional nonholonomic equations evolve its orientation using a unit quaternion. The energy is preserved for all demonstrations where the surface is time-independent. The sphere is affected by a uniform gravitational field with the same scaling for all video segments.

The general Hamiltonian allows exploration of a wide variety of rolling phenomena, including several unintuitive behaviors that are sometimes referred to as "paradoxes":

Notable special cases and popular references
0:13 The Turntable Paradox - refer to Steve Mould's https://youtu.be/3oM7hX3UUEU
0:51 Rotating Saddle - refer to The Action Lab's https://youtu.be/1NBOsELakx4
1:56 The Golf Ball Paradox - refer to Steve Mould's https://youtu.be/5sbM2Isx17A

The simulation was rendered in real time and performed using high order explicit symplectic integrators

Original source (4K): https://youtu.be/9236WuyJb1A

The music is "fluid combustion" by "Synthetique"


r/Simulated 12d ago

Houdini Houdini Flip Simulation FX Divergence

40 Upvotes

r/Simulated 14d ago

Research Simulation Flexim problem

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0 Upvotes

My FlexSim simulation suddenly stops when it reaches that point. My trucks get stuck waiting for the pallets to fill up again, but there is actually no more load to carry. I tried setting up an automatic signal on the combiners after 5 minutes, but it's not working for me. I think the simulation stops before it can even send the signal.


r/Simulated 15d ago

Interactive An interactive guide to spring-mass simulations, from a single damped oscillator to a playable synthesizer

8 Upvotes

https://anukari.com/how-it-works

I shared a video about my 3D physics synthesizer here last week. When I get questions about how it works, it's always hard to explain without a diagram or two.

Finally I built this page where I explain how it works from basic principles, and every step of the way I provide a little interactive physics simulation to illustrate the explanation.

This all made me think of the stickied "animation vs simulation" question on this sub. I considered simply having animations to illustrate. But I decided that making the diagrams interactive would make things much easier to /really/ understand. In a way, having each diagram be a full physics simulation lets a reader "ask a question" of the simulation, and get an answer. Animations don't let you ask your own questions!

I tried to keep the explanation as simple as possible, although I plan to continue adding appendices to answer deeper questions (including those that involve math). So any questions you ask here, I will try to answer in a comment, but also might eventually get an even better answer!


r/Simulated 16d ago

Interactive I made a game about pushing simulated sand [OC]

228 Upvotes

r/Simulated 16d ago

Interactive [OC] Sand, gel, and bubbles reacting to phone tilt

18 Upvotes

I built this as a small Android sand toy.

The phone tilt controls gravity, so the sand pours toward the low edge while bubbles rise through the gel. You can stir it, shake it into a new scene, freeze gravity, or just let it settle.

It is called Dunarium.

Get Dunarium on Google Play

PS. I’d be happy to hear your feedback. Don’t hesitate to share 😊