#nbody — Public Fediverse posts

First render in a while. It's a simulation nodes gravity simulation. I went through many phases of overcomplicating it to varying degrees of success before going the absolutely simplest approach of Newtonian gravity with a force filter that drops very close particles to 0 influence (otherwise particles get flung into the Twilight Zone). I cheated a bit and optimized calculation time by using a Merge by Distance in my simulation zone and only calculating the influence from those. It does cause closely-clustered points to have only as much influence as a single point. In another study, I had found a way to make the merged points have the mass of all the points in the merge, but the way that I did it had worse performance than the raw N^2 N-Body calculation.

The color of each particle is simply the absolute value of the velocity, mapping XYZ to RGB.

I should work with Geometry nodes more. They are very stimulating. My real addiction is programming, and I often neglect my art, and geo nodes give me the opportunity to scratch both itches at once.

I wish I could get this one done in Cycles, but it's just too damn slow. Low frame time and denoising alone would make a 30 second render take over 5 hours, and it doesn't really look that much better than Eevee.

#Blender #BlenderEevee #EeveeRenderer #EeveeRender #Video #MotionGraphics #MoGraph #Gravity #GeometryNodes #SimulationNodes #Suzanne #NBody #NBodySimulation

First render in a while. It's a simulation nodes gravity simulation. I went through many phases of overcomplicating it to varying degrees of success before going the absolutely simplest approach of Newtonian gravity with a force filter that drops very close particles to 0 influence (otherwise particles get flung into the Twilight Zone). I cheated a bit and optimized calculation time by using a Merge by Distance in my simulation zone and only calculating the influence from those. It does cause closely-clustered points to have only as much influence as a single point. In another study, I had found a way to make the merged points have the mass of all the points in the merge, but the way that I did it had worse performance than the raw N^2 N-Body calculation.

The color of each particle is simply the absolute value of the velocity, mapping XYZ to RGB.

I should work with Geometry nodes more. They are very stimulating. My real addiction is programming, and I often neglect my art, and geo nodes give me the opportunity to scratch both itches at once.

I wish I could get this one done in Cycles, but it's just too damn slow. Low frame time and denoising alone would make a 30 second render take over 5 hours, and it doesn't really look that much better than Eevee.

#Blender #BlenderEevee #EeveeRenderer #EeveeRender #Video #MotionGraphics #MoGraph #Gravity #GeometryNodes #SimulationNodes #Suzanne #NBody #NBodySimulation

So now it is time to talk about the physics and how this all started so here we go

I woke up one day with this in my head. It is a modification of a toy I would used to explain information density using Conway.

It seems so obvious in retrospective.

#Nbody #physics #science

https://github.com/NoorMathematica/phys-core-001_n-body_interactions_in_euclidean_space

Some performance improvements incoming - focusing on a smooth multi-body space engine has been my focus as I took a few days to just clean up code, APIs and - happily running at 120fps (at 96x speed - where the n-body physics is still relatively stable) - the main bottleneck is now in the WebGL rendering itself!

#devDiary #screenshots #gameEngine #gameDev #simulation #astronomy #nBody #threeBodyProblem #webGl #threeJS

#blog post - Teskooano .plan 00003: Planet Updates - https://teskooano.space/plan/00003/

Read about the new planet shaders, along with the ability to edit them in real time within the engine, and more upcoming improvements

#gameDev #indieDev #simulation #nBody #update #screenshot #video

Oh no, I just noticed that the @reboundbot hadn't posted any updates recently. I had to make a small change in the cron job after an update. Should be working again now. So follow it if you're interested in #nbody #dynamics and #planets in general.

A new paper by Lu et al. has cited REBOUND:
TRACE: a code for time-reversible astrophysical close encounters https://ui.adsabs.harvard.edu/abs/2024MNRAS.533.3708L/abstract #nbody #astrodon

A new paper by Agrusa et al. has cited REBOUND:
Direct N-body Simulations of Satellite Formation around Small Asteroids: Insights from DART's Encounter with the Didymos System https://ui.adsabs.harvard.edu/abs/2024PSJ.....5...54A/abstract #nbody #astrodon

A new paper by Rometsch et al. has cited REBOUND:
FargoCPT: A 2D Multi-Physics Code for Simulating the Interaction of Disks with Stars, Planets and Particles https://ui.adsabs.harvard.edu/abs/2024arXiv240116203R/abstract #nbody #astrodon

We already have over 100 registered participants for the first ever REBOUND conference! It'll be fully virtual and free to attend. There is still plenty of time to sign up or submit an abstract if you're interested in #nbody #simulation, #exoplanets, #solarsystem, or any other aspect of #dynamics. https://hannorein.github.io/rebound24/ #astrodon

Just published REBOUND version 4.3.2 with even more visualization improvements!

All the examples can be run directly in a browser on readthedocs: https://rebound.readthedocs.io/en/latest/examples/

#astrodon #nbody #astronomy #astrophysics

I've implemented a framework that allows users to programatically control the #visualization of a REBOUND simulation. Among other things, this can be used to render animations. Here's an example running in web-browser in real time: https://rebound.readthedocs.io/en/latest/emscripten_c_examples/animation_solar_system/ Source code: https://rebound.readthedocs.io/en/latest/c_examples/animation_solar_system/ #astrodon #nbody

I've been working on some improvements to the built-in real time #visualization feature of REBOUND today. This example shows the Solar System. First, stepping through the simulation one timestep at a time. Then showing the long term evolution (note the precessing orbits). The simulation is running at full native speed. All the rendering is done in real time using #WebGL and requires no external libraries. More details will be in a forthcoming paper. #nbody #astrodon

Our new paper is on the #arXiv / @OJ_Astro today! We derive a new timestepping criterion for #Nbody simulations with adaptive integrators such as IAS15. We show that our new criterion always resolves all physical timescales in Keplerian orbits, regardless of eccentricity. It's also much less likely to be affected by finite floating point precision which previously often led to slow or stalled simulations. The new criterion is now the default for IAS15 in REBOUND.

https://arxiv.org/abs/2401.02849

Like in previous years, I'm only passively participating in #Genuary2024 and posting relevant existing experiments/sketches/pieces... Two more candidates (in addition to the recent boids work) incoming for the "Particles" prompt, incl. this first one from 20 years ago:

IdeaSpace - a cyclic universe (2004)

http://toxi.co.uk/p5/ideaspace/

"A space with a steadily increasing number of moving particles attracted by slowly moving, invisible gravitational centres. The cyclic nature of the space itself acts as four dimensional history, causing each particle to leave a persistent trace in time as well as in space. The paradoxical result of this setup is that whereas the number of particles is approaching infinity there's no increase in computational cost."

This piece was shown at my first solo show @ Mediaruimte, Brussels in 2004. It was started with a "small bang" event (aka spawing the initial particle system in the sim) during the exhibition opening and by the time the show was finished 2 weeks later, the (sim) space was almost entirely white, almost completely filled with particles...

Ps. In the video: 1 rotation = 1 cycle of the simulated universe.

Pps. Also worth noting that this was done entirely without (before) GPUs, all software rendering only. Each particle is actually shown as thin line from its previous position...

#Vintage #GenerativeArt #Generative #Genuary2024 #Art #Particles #NBody #Gravity #Visualization #CyclicUniverse #ProcessingOrg

The Virtual Astronomy Software Talk (VAST) that I gave recently is now available as a video. I talk about accelerating N-body simulations using AVX512 instructions.

#hpc #computing #astrodon #nbody https://www.youtube.com/watch?v=xaC51s25T70

A new paper by Overton et al. has cited REBOUND:
Retrograde discs around one component of a binary are unstable to tilting https://ui.adsabs.harvard.edu/abs/2023arXiv231110864O/abstract #nbody #astrodon

🚨 New paper!

We re-implement the symplectic WHFast integrator for planetary systems using #AVX512 instructions. We get an almost 5x speedup for a typical integration of the Solar system.

This is a big deal because no matter how much money you spend buying a cluster or GPUs, you just cannot accelerate small N-body integrations. They are inherently sequential. But now a 5 GYr simulation that used to take a week to finish only takes 1.4 days.

#hpc #astrodon #nbody
https://arxiv.org/abs/2307.05683