i exist too!

and hence your statement is wrong

but i exactly came for that...im trying to make a solar system simulation xD

instablaster.

He just said that cause the title is about physics engines not engineless plain n-body simulations.

Thanks!

Hell yeah! tyty

Well said

Thanks! I'm glad you find them clear :)

Thanks! I'll get into that in the next part about physics. I don't have it planned, but when I get to it I'll lean a little bit more into the math. If you want to check out the code for the response, it's here and decently readable: github.com/IainWinter/IwEngine/blob/master/IwEngine/src/physics/Dynamics/ImpulseSolver.cpp

Thanks! You know what, I think that might just be the way. I could cover some of the algorithms that have few concise explanations. I bet I could make a good GJK video...

@@Winterdev GJK is an advanced and often poorly explained distance algorithm. To be meaningful it also requires an understanding of linear algebra and affine geometry. I'd like to see how you handle it.

Thanks! Next vid should be up in the next week or so, but it's about sand lol

Haha thanks, that is my goal, to make the tutorials that I needed. It seems I'm not the only one that wished there was clearer info on these topics! :)

Glad I could help :)

Thanks, I'll note that to do next after these sand vidz. That's prob not going to be for a while, but if you want to get some ideas the source code is here and not too messy, I think this was also my 2nd or 3rd go at it github.com/IainWinter/IwEngine/tree/master/IwEngine/include/iw/entity

Thanks! I'll try

Yeah plus a couple As in final school projects haha. And it’s fun to have a system that you know every detail of

Thanks! More videos coming soon, a new semester just started and I am bogged down with work though :

Thanks

I'd check out the EPA one :p

Thanks! They inhreit from 'Solver' and process each CollisionPoints. The idea is that the impluse one solves for the force of each collision, and the position once corrects the position directly for some error correction. You can check out the source of these here github.com/IainWinter/IwEngine/tree/master/IwEngine/src/physics/Dynamics

Thanks! Yes, I think I am going to throw that in with angular stuff when I get back to physics. The code is decently clear if you want to look at it github.com/IainWinter/IwEngine/blob/master/IwEngine/src/physics/Dynamics/ImpulseSolver.cpp

@@Winterdev Thanks I’ll try it.

I just use a js file that switches classes around each ‘key frame’ and then I built another web tool that generates it

Really? I was under the impression that was only going to involve some slight edits lol. Looking forward to it now... :)

@@Winterdev Maybe it actually is a slight edit, I just could have done it extremely wrong xD Looking forward to your video about it to find that out)

This was talked about quite a bit over on the hn page here news.ycombinator.com/item?id=24016718#up_24018883. It's a pretty interesting read. I've been using HTML and CSS for these 😂

It started as a project for a physics class and then I realized I could use it for the simple games I was making. Over time I got invested in it :) I think other than coding exercises you should use a library, but I think it’s important to understand what the computer is doing so it’s def worth it to try and make one yourself.

Thanks for the comment! Someone in the hacker news discussion was talking about that on similar lines news.ycombinator.com/item?id=24019099. My understanding is if you update the velocity then the position in the code, ∆x = ∆vt and ∆v = at. When you take the derivative you get ∆x = ∆v + a∆t^2 / 2. I think in the code if it were too update the position then the velocity, this would be an issue, but because the velocity gets updated then the position, those equations are equivalent.

@@Winterdev Thanks! Yeah, I guess the key is that we expect ∆t to be so small that we can afford getting some measurement error by calculating ∆x as if the object were moving uniformly without acceleration whatsoever. Also, like you said, this would be an issue if we calculated ∆x first, since then we would not really use acceleration anywhere at all. Thanks for clearing that up!

I am running into the limits of testing everything against everything right now, so once I make my version I can make a vid on that for sure!

Thanks! It looks like its chosen me for today lol

The performance will be trash for more than the reasons you listed. Consider that every static object will need a collision test between every other static object, which is ridiculous. Which objects collide with which objects is something you need to tightly control (say, should a bullet interact with a gravity volume?) for performance and behavior reasons, and the approach in this video isn't good enough.

@@MisterFanwank Yeah one of my biggest regrets with this design was the double dispatch call. I later found a Valve pdf (page 33) that describes a 2d array of function pointers, then you use a ColliderType enum to index it. This lets you define all the possible collisions in one place and effectively centralizes the virtual function table. You could add another enum and follow this pattern for the object collision masks. The performance worked for my tiny games, but you definitely need a form of broad phase check/data structure for anything larger. valve: pdf media.steampowered.com/apps/valve/2015/DirkGregorius_Contacts.pdf

Thanks! And I used C++ for this

No I made that myself. This didn’t need anything complicated math wise so I just made my own

@@Winterdev Oh is there the source code, or tutorial on how to do it?

There was but I’ve changed it form what it was for this project. For this all it was an x y z and operator+. In the collisions the dot product is used I think.

That's the long term goal! First I gotta finish this sand mini arc and then I want to go library by library and make vids like the first one

It’s in the article :p github.com/IainWinter/IwEngine/tree/master/IwEngine/src/physics

@@Winterdev Thank you, and sorry for the harsh comment, I just see a lot of bait on YT nowadays, trying to give ppl the false sense they've learned something when they've just made eyecandy for viewers

Yes that was a dumb mistake! Thanks for catching that :)

It’s a little unclear but those come from me. All you need for this are structs with 2 or 3 floats for x, y, z and maybe a length / dot product function which are both 1-2 lines so I didn’t cover that. I might add a small gist to the description

@@Winterdev A gist about it would be greatly appreciated, I for now created my own PhysVectors with the required coordinates and operators that should do for now.

I changed it to be a table of function pointers later on which was much easier to work with. I don’t like the double dispatch at all looking back

I don't know your specific code, but I'd try and start with something as simple as possible to get an idea for how it should come together/what the issues are. You could start with making a 'Collider' that is just the sphere one because it's the more basic . Then you could store these in a list, really anywhere, and loop over them getting the responses if there is one and moving them by that response. I might make a version of this with impl, but not for a while as I am trying out some other topics besides physics. gl with your code :)

@@Winterdev Thanks! I ended up getting it working but the plane collider is infinite along the x and z coordinates, did you run into that?

@@thebutterappletutorials6553 Yes that's what I have. Nice job!

@@Winterdev Thank you!!! Gonna move onto the Mesh Collider stuff next! (GJK and EPA) Would love to see videos going into the math (how to attach it to a custom model and have it work!)

Oh nice good luck!! When you say attaching it to a custom mesh, is that from a visible mesh to a physics one? Or any type of collider attached to whatever game object so they move together.

Thanks, I'm still getting that down, there are written versions as well so I don't really know if I should made fast videos or not... Here is the article if you're interested: blog.winter.dev/2020/designing-a-physics-engine/

Not a vid but here is a “3 fold poster” I made for a class final project. winter.dev/physics/ it’s not complete but a good start

Well it depends on how realistic you want it. I’ve never made a racing game but you could do what you described or you could just have a simple obj following a path like Tube Slider

@@Winterdev I did some digging after leaving that comment and that is a common way to do it apparently when making physics for racing games. By having the wheels separate objects from the body, still attached of course, and giving them physics like friction and then just change them depending on what you want wether it’s a drag, drifter, or off-roader

Thank you!

Trash you rud

I use visual studio but in theory you could use notepad lol. The build tools kinda abstract that away but I haven’t tested it with anything else

It’s just 3 floats and you pass it x,y,z or it defaults to 0,0,0

Thanks, if you watched my recent dev log I have these asteroids flying around that need the rotational collision response so I’ll make a vid covering colliders when I talk about that in a couple weeks

Yes I did a video on it :)

Lol I feel your pain. OpenGL is as complex if not way more than the physics engine and impossible to debug if you don’t know where to look. I’d lookup GLFW which wraps all the nonsense (window/input/update loop) up for you, but you still need to pass a mesh by hand and have shaders setup. Maybe look for a renderer library that is made to be as simple as possible

@@Winterdev yeah in using GLFW. I'm a first year undergraduate computer science student. I built a ray Tracer and thought "all this math was cool, I should make a simple little physics engine." I think I'm gonna be able to understand GLFW and the physics but combining them might be problematic, I will figure it out! Or not, I have an internship starting next week so bit of a time crunch.

You should make a Transform struct that has a position, scale, rotation and a function to get the transformation mat4 from those. Then the physics engine can take this too and the colliders can stay in relative cords along with the meshes (or sdfs?)

​@@Winterdev Hello, Thanks for this great video. I'm a big noob on both OpenGL and c++ but this inspired me a lot. Regarding your answer above, I have a question. When rendering say circles or spheres, the renderer will need both the position of that object, and the colliders 'center', and add them together, right? But I can't reach the variables radius and center from the class SphereCollider In my renderer as it simply interprets them as the base class "collider". Would I have to create a similar function-structure as you did with the colliders for the rendering or how does this work? any tips? Thanks, John. Edit: I mean, why is the "center" variable in the SphereCollider needed? can't it all be handled from the position in the transform? And the plane, can't it just be implicitly oriented with normal (1, 0, 0) and then let it's transform take care of any further rotations?

The trick is that the rendering world is separate from the physics world. You need to have some sort of object that represents the position and pass it to both, then they both add it to the colliders center and mesh verts. So everything is relatively positioned to a shared position.

many lines of C++ called wEngine

If you’re asking where to make something like this? Anywhere you can see the results! So you could print to console or use unity to easily display, tho that’s in C# not C++

The frozen code is in the article here blog.winter.dev/2020/designing-a-physics-engine/. And the working code is in the git repo here github.com/IainWinter/IwEngine/tree/master/IwEngine/src/physics

Funny enough, it's going up tomorrow :)

Aa it does get 0’ed I don’t think I mentioned that tho. Good catch

Someone else was having their comments deleted too, idk why sorry. I watched that video and it looks like that I am using what's called semi-implicit Euler, which Eric concludes is the most common. That makes since to me because it's what you naturally end up with when translating the kinematic equations directly to code without thinking about it. Let me know if I missed something, thanks for the comment :)

It's edited now, but here is the live code. github.com/IainWinter/IwEngine/tree/master/IwEngine/include/iw/physics github.com/IainWinter/IwEngine/tree/master/IwEngine/src/physics You can step back in time in the commits to find the og code.

(;´༎ຶД༎ຶ`)

nay you should try it ;)

I'm far too deep in the mindset to turn back now lol :(

If you're talking about applying forces, you'd do that in game logic with some collision event from a trigger for whatever region you wanted the force field in. Not too sure what you mean by 'response to continuous field' though

:(

@@Winterdev I'm trying to teach myself programming and makinga game in roblox and I learned basic scripting like scripting a part and achoring them some simple scripting but still its realy hard to understand I tried it but it didn't worked I got discouraged and now I ended up giving up.

@@RoidoStuff there are many tutorials available in KZfaq. Learn c# and then use unity game engine or learn java and use android studio to make android apps and all.

@@ahmedaghadi8281 yeah I've been working on many games rn on roblox and I also learned some basic scripts

Thanks for point that out, it’s back up!

@@Winterdev Ok I confirm it's working back :)

Yeah it’s up to you to allocate them efficiently. I’m not sure what box2d is doing with proxies but that might be cool to look at for a 3rd option.

spotted