I'm Coding an Entire Physics Engine from Scratch
Vložit
- čas přidán 8. 10. 2021
- github.com/Gonkee/Gepe3D
Music:
Kevin MacLeod - Fluffing a Duck
incompetech.com/music/royalty...
MoeMentum Beats - Raspberry
/ moementumbeats
Mii Channel Trap Remix
lano - pain
• lano - pain - Věda a technologie
Ah, the programmer's credo:
"We do things not because they are easy, but because we thought they were going to be easy."
ON POINT
Not the programmers only👍
Yeah that's about everything in a programmer's brain
Then we see thousands of mistakes
@@tex1297 literally just anyone working with stuff that involves a large amount of math
@@filipthunell8631 right +any creative people of any field
"I can probably do it better" every programmer, hell, every person creating something says this and immediately regrets their decision until it's complete
It's the only thing that keeps world from not using 500 year old software lol
Instead, we have e.g. JS frameworks mess, being flooded by D-K syndrome folks on one hand and driven by shiny object syndrome folks on the other :P
I remember that I was still with only 2 years of experience on Roblox Lua when I saw that time's best vehicle module. I wasted a month or two trying to make a better one just to abandon it and realise that I can do it now, but if I attempt it's not even going to benefit me in any way.
Except that's how innovation is done
@@dimaryk11 not always but sometimes it does result in innovation.
imagine how many cool libraries we wouldn't have if the authors had realized how much effort it would be
8:10 why does the ball look like the coronavirus 💀
I did physics sim stuff too (and want to do more) and it seems like our brains are of similar smoothness, so I understand your pain. It's comforting to see someone else struggle with the same stuff.
Can only agree! I'm working with an advanced optics sim at the moment and some days I just wish I could close my eyes and forget my existence for a little while... But when it works, then it's all worth it again!
i dont even code, im a civil engineering student
just come here to see people in pain and having fun
ahhhhh one of my kind
Smart minds think alike
Subbed
I think you need some damping/friction forces. It looks like the springs in the ball are perfectly elastic right now, so each impact will just increase the internal pressure, causing each triangular section to oscillate more and more (like simple harmonic motion, but complicated since it's in a connected mesh of springs). Dissipating the energy as "heat" should keep the ball's internal pressure more stable and prevent the triangular sections from vibrating faster and faster.
At high enough friction/viscousity this ball will behave like a solid object, by the way.
@@blinded6502 with explicit integration it wont ever be able to use a high enough viscosity/stiffness to make it behave like a rigid body.
Yeah I think they should have some friction relatively to the other points. If they go against the stream then friction. Have fun! xD
@@gaussgreen7921 Of course. Unless you advance simulation by very tiny time intervals, and possibly even increase precision of the coordinate system.
Yeah also the imperfections of solving the differential equations numerically could be causing a feedback loop of growing energy in the springs
Hey Gonkee, I came across your video some time ago and it inspired me so much. I loved seeing your entire raw process, struggling and learning an entire language from scratch. It gave me a huge motivation boost and made me realise that it's possible to pull off something as crazy as this through sheer will. Thanks a lot for this. You're a genius.
I was cracking up at 8:53. So that's how a bouncy ball behaves when it exists in an atmosphere that somehow lacks entropy.
You could probably achieve more stability if you could somehow make the ball leave an imprint of its momentum on any object it comes into contact with, on the understanding that contact between two objects must achieve a null state before contact is broken (like with objects that are artificially forced into place, like walls that hang in the air, returning equivalent negative values). In nature, we are supposed to subtract the influence of the struck object(s) from the original trajectory of the striking object to find its path through space. If we don't, the moving object inherits that extra energy of being struck back by the wall and internalizes it, without losing any of its original velocity, causing the structure to eventually warble out of control the longer it moves.
I don't know how it works in code, though.
Oh right. So his sphere heated up.
@@matthewscott336 that's the best way to say it
When I first read the title I thought it said "Coding an entire physics engine IN scratch", that would have been insane
Omg same so now i sad
oooauaiaiaiaiauauauaauauauauau how to unread things
@Biglyp people have made 3d stuff in scratch
@@katteisace4563 yeah buts it’s not true 3D
same
#1) There seems to be not enough decay to the energy in the springs
#2) The Energy is stored in the single springs and not dissipated to the other springs, allowing for resonance. And as those who resonate more will re-collide earlier, there is a positive feedback loop to this resonance.
Ok science boy
I am not sure about this but do you adjust the area in the force formula, according with the mesh count?
It just might be that there’s no damping at all
nerd
when are you gonna upload on your yt channel again? your songs are very nice
3:07
Hexagons, are the bestagons
That epic montage was amazing, it captures every aspect of "learning" a new skill :´)
lets all just take a moment to aprecciate the devs of the simulation we live in
Thanks 😊 . I will not delete your soul until you are 90 year old
@@motherisape can you boost me so that I look like I'm 50 when I'm 90?
@@motherisape Yo, Tell the guy who created my code that his choice of skill point distribution sucks.
imagine having to code all the quantum particles and then atoms and physics and complexity of this universe, those beings may as well be gods compared to us
@@casualbydefault my bad, we accidentally used an older version of the skill point distribution algorithm when we made you
Amazing video. I love doing a funny and unnecessary project that takes part of my soul while I'm making it. Subscribed
This dude's got some hilarious editing. Keep it up!
Vids like this motivated me to code,thanks buddy
Disclaimer: I know very little about numerical integration. But maybe using a symplectic integrator (e.g. velocity verlet) instead of Runge-Kutta would help with the oscillations you're getting.
What, I thought RK4 was meant to be the best one
@@Gonkee Depends on how you define "best", there's always pros and cons
@@Gonkee Also there are symplectic versions of Runge-Kutta fwiw
@@Gonkee Although RK4 is a big improvement on Euler method, and is good enough most of the time, it still can be improved (usually in the cost of computing effort and complexity of the algorithm).
Specifically, at 7:10, as a result of increasing the spring coefficient to 999999, the solution probably now have very high gradients and your time-step is probably not small enough to capture it and the solution completely diverges. In the Numeric Analysis world, we say the problem/equation is "stiff".
If you want to somewhat keep the simplicity of the integrator, you might be interested in the adaptive RK45 method. If you are willing to invest in more complex methods, maybe consider researching into implicit RK methods.
This is the first time I hear about the Verlet's method proposed above, but maybe it's also a good fit.
Disclaimer: I never used implicit RK methods, but I heard from a professor that they are used to solve stiff problem.
@@Gonkee i think the problem is that you're trying to solve a set of partial differential equations by treating each PDE as a separate ODE. im by no means an expert but afaik there are algorithms designed for solving PDEs that are much more stable
Thank you Gonkee. You have made all the pain of teaching physics worth it. I am thinking that I can use your video as motivation for my students. Would be great for the computational physics class that I taught a couple years ago. I do feel a bit guilty, that I can't go help fix your code right now. I'm sure you'll figure it out...you are the best type of student. Very proud of you young man.
Your videos are SO funny!! You capture all the frustration I am feeling but make me laugh while watching 😁💀👍
I feel your pain :) You still managed to code an awesome demo 💪
You got style, patience and brains man. Keep it up. I’m not even in this field but watching you think through the problems really made me smile. You’ll go far.
You have an awesome and interesting way of communicating your ideas and experience. I would love to see some NN, or other machine learning subjects tackled by you.
dude. great video. You're a sadist...and I love it, because this is educational and fun (and super funny (I LOL'd a ton))! Also subbed
I’ve stumbled upon your channel & have never been happier. 1 minute into this video and you have me cracking up
boredom really brings you to a journey of pain and suffering. amazing video as always man, i'm loving this format so far :D
I laughed my ass of. I don't care how good or bad this actually is, it's the funniest shit watching
Is it just me or is that comment T H I C..
Dani: no not now I’m working on karlson
CREEPER MAN
@@Jake2534 yoooo
awesome and entertaining video man! hope you the best
Bro, ur insane. I love that type of humor so much, the editing is well paced and those random images there and here alongside all the dumb memes, that shit is insane. Keep going on, the content is insane as well man
Gonkee: "I'm coding an entire physics engine from scratch"
Me: "You poor poor soul"
I like how his equation for the ideal gas constant has all the capital letters for FART in the right order at 5:35
"How many of the average person's fart gasses are needed to make the pressure in an ico sphere go from 1 atmospheric pressure to 2 atmospheric pressure?"
@@xXJ4FARGAMERXx a lot
damn
@@xXJ4FARGAMERXx that is a genius question. I don’t know why the worlds best scientists aren’t working on it now. Or maybe they are…
@@xXJ4FARGAMERXxhaha text in between username go brrrrr
Excellent sense of humor. Keep it up, buddy!
I’m a business major and I still enjoyed the video. Good humor & editing, keep it up!
7:40 as someone who took numerical integration classes from physicists, good luck with that : p
Oh no you make it sound like it'll be a terrible experience
@@Gonkee It will.
@@Gonkee to be honest, it's kind of a coin-flip in my experience, but when it's bad it's really bad
Can’t wait to see the next update video! It looks like a really cool project.
Dude, you are hilarious and I have so much respect for you doing this!
First time watching your video, you have done a remarkable job. I'm sure your channel will stand out as it is already.
Im in my first year in college studying software engineering and I thought chemistry was gonna be useless to me.. but I now saw you using the ideal gas formula and now I’m motivated to study 👍 thanks, and great video!
You are new, to this. So I make an exception. The first rule of thermodynamics is: Noone talks about thermodynamics.
Your humor is spot on and your content quite unique. Subscribed.
Just... amazing! Thanks for your content.
Great vid man super entertaining
This makes me feel way better about my spring-mass system I made. It ALSO was sensitive to the parameters and exploded in a very similar way :)
That was too much work for the amount of subs you have! Such an underrated channel! First video of yours I’ve seen but I’m now subscribed haha. Keep it up
Thank you. You just took all my motivation learning to code.
Awesome video! Thank you!
As a CGI Artist I have to say you made it insanely good! Nice work because you did it alone and didn't knew stuff about it before.
1. Fix: (Not easy to implement)
When solving the harmonic oscillators (these spring mass thingies in the icosphere) with an explicit scheme like RK4, the systems energy increases from numerical errors until it diverges to infinity. When solving with an implicit scheme (much harder to implement), the systems energy converges to zero and is therefore to be preferred.
2. Fix: (Turbo easy to implement)
I assume You did not implement a damping term. In reality, a pendulum or an oscillator never oscillates for ever, it loses energy due to friction and shit. If You include a small damping term into the oscillators You will see iz gunna wok.
3. Fix: (Bruh)
Just decrease the time step size. The RK4 scheme should do better at 120Hz or 240Hz.
He actually implemented a daming term in 6:07
The parameter 'dampingConstant' is probably set too low - much too low
A high damping coefficient will make it go boom too, the more force is generated the smaller your timestep has to be to keep it stable.
@@madmax43v3r Yep:
If the step size is too large on an explicit scheme, everything goes boom.
There are situations where a damping term generates a converging solution.
Would using double floats help? (It helped on my micro gravity videos... Kept 1/r2 from going to infinity at smaller proton scales.)
@@TheRainHarvester In this case:
The machine error is orders of magnitudes smaller than then error of the integration scheme.
=> Doubles would probably not make a significant difference.
In Your case:
The major source of errors was the machine accuracy for small float numbers. Hence, double precision solves the issue.
@@Xbox360SlimFan I'm dealing with integration errors now: unequal approach and departure simulation ticks.
This is amazing, subscribed
Oh man I laughed so much at this video. I love your sense of humour. Subbed.
As a fellow sleep deprived math enthusiast and programmer who also likes to inflict pain upon himself with impossible projects; this video and your channel as a whole is great. Thank you "Inspecto" :)
7:30 - I wish I had another like button to press here.
This is amazing! (I also want to make my own physics engine :)) Also, it's really cool how your new channel is *already* more popular than your old one :O
Respect dude. ✌️please stay awesome.
i'd also enjoy longer videos on stuff like this
It's truly a joy to see others go through the pain I'm subjecting myself to, okay that sounds cruel, but at least it makes me feel better! You did a great job though, I'm looking forward to seeing more simulation stuff (and I would unironically watch 2h of this)
Never saw you before, I'm 4 minutes into the video, already subscribed. Keep up the good work man ✌️
this is the first video I see of yours, and I really love the content, you def deserve a sub
Your style of comedy is amazing. Time to binge yet another creator's entire existence in just a few days.
nah the kid is pretty cringe i'm glad i'm using sponsorblock to skip his fillers
@@moonshot3159 ironic, 'cause calling people cringe for doing what they love and sharing it with others is pretty cringe if you ask me.
@@Lin_The_Cat_ what you just said has earned you a ticket to cringetown.
Good stuff man. I'd find some Discord group with coders that geek out on physics and ask around. In the mean time, your video style is great.
I like your skills and video, thanks for this content
oh my god. youre the guy that did the awesome godot water shader tutorial. cool channel!!
3:20 "how to make an iron golem"
what a gamer
lol, I made an entire soft body engine too! xD. I just made some springs applied some forces and tweaked it until it looked kinda decent.
If someone wants I can publish an unlisted video with my bouncy engine.
You got some real balls by the way going into that project with like no experience with the language or the only a little bit with the renderer, on such a giant project. Maybe I should do that more, just go into the hardest project I can think of.
Anyway, I love the jokes in the video! The vid was a feast.
this made me laugh a lot. Great video man keep it up and the sky's the limit
First Gonkee vid, easy sub
nice video gonkee. I studied 1984 in high school as well, not as my physics book though haha. keep it up
Wow what a coincidence I also studied 1984 in highschool
Wow! Same here. What a small world.
@@cardscook7721 No way! I too studied 1984 at high school.
@@JordanChung Bruh at this point these comments are looking like those scams in crypto videos "I too traded with mrs laura". lol🤣
Now do it IN scratch
Nice video! Yeah Runge-Kutta 4... when I learned this, it was like cake and roses. Joking, it was like pain in my pineal gland. But I managed to get it working. It actually took me about a half a year to actually understand the papers of Runge-Kutta 4 and how to advance it. I mean you are taking one second and dividing it to pieces and then summarising the pieced simulations together and passing as a single second... But it sure does make a huge difference! I integrated it to my vehicle simulation and I actually had to rewrite about 90% of the simulation, just to make it compatible and there still are some minor issues, just like you are having haha. Maybe you can advance your soft body to a metal simulation, by adding some fading dampening, you could make a seriously cool damage system. Fluids are the hardest, would love to see how you approach it.
Nice work, bro!!!
Friction and dampening, my friend, that is the key to stabilizing. There are multiple different kinds, and often they are small enough to be dismissed. But whether it is air resistance or the springiness being dampened by the rubber converting motion into heat, or whatever, it is usually some variation of a force (/acceleration) in the opposite direction of the velocity, and is some proportion of the velocity or the velocity squared. So it will always attempt to counter the velocity, and bringing the system towards a stop (and gravity in this case keeps adding to the motion of the system). And since the velocity becomes slower and slower, the friction/dampening proportional to the velocity becomes lower and lower, thereby making the slowdown exponentially decreasing (sort of asymptomatic towards stand still).
If you think about it: the soft-body eventually derping out is because of heat, even if heat is technically not implemented.
The potential energy gets transferred into velocity of the points, giving the initial illusion of bounciness.
The body being a closed system means that entropy must reach an equillibrium. It wont just keep bouncing as this is a state of high entropy, but instead each point will eventually go into it's own direction.
This results in things derping out unless you transfer energy out of the ball, for the same reason things derp out if temperature increases too much.
This isn't even technically a bug, just not working to simulate large scale objects, which are usually made up of more particles then you could simulate in a lifetime.
ah yes, the reaction to the mathematics of collision, i know that one from experience
You sir deserve a sub - that’s hilarious !
Dude what you did is amazing. Especially knowing what you know in the amount of time you did it in. This is really impressive! The most I can do is draw a square. Actually, I can't even do that anymore because I forgot all my high school Java. Keep it up! You will be big brain one day! (youre already big brain tho
6:45 - it's not the accuracy of explicit methods that's bad - it's instability. You raise your dt too high - you get an unstable system. And Runge-Kutta is excplicit too, so you'll inevitably will bump into problems with stability when you crank certain numbers too high or too low. Also, if your spring constant is very high - it's better in terms of calculation to implement them not as springs, but as a rigid rods. Also, you can add some dampening to your system to "vent" some instabilities that accumulate over time. I'm basically trying to accurately simulate problems like that (inflatable shells dynamics) and it's a living hell (But i'm going to use FEA since I don't need any real-time simulation).
Basically you're avoiding at some level rounding errors that can occure.
@@johnsherfey3675 it's not just rounding. But he could use double floats.
Sometimes it's the approach and departure i describe in my micro gravity simulation.
"I'm bored, so let's do it again", that is the best reason to do anything
Comedy on point for this one, enjoyed it a lot!
Lmao, very funny and actually inspiring video! :)
I hate to be the 70th comment but how are your first few videos so good? Also i love the low bitrate tobu candyland lmao
Oh, and a dani reference too, this channel is going places
Ah yes, C# and OpenGL, I regretted doing that every single time, yet I still keep doing it
Nice one bro. That's an awesome project. During lockdown, I decided to make a program that tries to predict which stocks are going up and down. Programmers be crazy...
This is such a good video!
Modified Euler/ RK can be scaled up even more. For some of my physics simulation I use ODE45 in MATLAB.
"Okay i don't know how to make any of these but im sure ill figure it out."
- Every programmer ever
love the energy
Qué grande, te amé, bro jajaja super like
“it’s 2 weeks later, and i’ve probably lost 5 years off of my lifespan”
ah yes, mathematics
One downside to the ico sphere, you don't get fine control over the resolution of it, if you want to increase the number of vertices, you have to subdivide it. Whereas UV and square spheres can have X by Y number of vertices, which is better for things like spherical terrain.
Good job! All you are missing is surface tension, a surface tangent force between vertices to distribute them homogeneous, in these case a spring like force pointing from vertice to its neighboring vertice on the mesh.
awesome video!!! Maybe to fix the ball you can add some sort of communication between adjacent points so that the small oscilations dont get out of hand?
2:37 Fun fact. you can turn a quadritateral into 2 triangles with a simple line.
Then each triangle wouldn't be equilateral though.
I once made a cloth simulator (spring-mass system) and it had similar instability with ramping oscillation. It became a lot more stable when I introduced some sort of fake friction (just multiplied the velocity of each point by 0.99 every time step).
Ew, that's a horrible way to do it
@@FunnyFavor
I'm not saying he should do this exactly in his project, it's still insightful information though.
And for my project, it was perfect.
@@FunnyFavor i would do that
Can we post the result of your cloth simulator? 🤩
Dude you're so funny, I sense a sharp rise in subscribers in your immediate future. Michael Reeves vibes!
Great video and learning exercise. I’d recommend implementing a vector class so you can reduce your code by a factor of three!
You might want to use implicit methods. The common technique in Physics-Based animations is Backward Euler. This would be much more stable. If you really want to keep using explicit methods, make sure your time step is low enough and maybe add some damping. David Levin from UoT has uploaded superb videos for course on his youtube account. You should be able to learn everything you need to implement the other parts of your engine. PBD might have been a nice alternative way to make everything fit seamlessly in the same simulator, but I have personally made it work with FEM.
Why would that be more stable?
very cool
ayo this the guy i made a world class instant messaging platform with
@@Gonkee yes
this is actually really cool tho great job
I love how you try but then it turns out to be hard. That’s the only way to learn your blind spots. Hope you can improve it in the future!
Love the high quality Montage music
I love how you tried to make a physics engine and ended up making covid. 3:35
2:09, dammit.
Dude! I love your work and the way you produce videos
Now I inspired to do the same staff in Entitas approach (ecs).
I’ll share results
Nice job man