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The upper system is left-handed, no way anything uses that. I’ve seen the same with the Z flipped in some video games and it’s not that bad
One of those people would be wrong.
I find that it depends on the context. If it’s side view only it’s essentially 2D in which case Y is up.
For anything where you get a proper 3D view, X is up.
y-up ftw
It’s easier when writing 3d renderers cause the x and y coordinates of the 3d points eventually become the x and y coordinates of the 2d points on screen and it’s easier to keep track of
Except when you are working on top-down game/3D environment. In which case you are constantly changing between Z and Y…
Indeed, depth buffers etc are from the z coordinate.
Also on the web, the “z-index” is the depth of elements in the world of CSS.
I wonder in which contexts y would make more sense as the depth.
Top one is incorrect. Z needs to point outwards.
I know Z as upward. X and Y were always on the base plane representing length and width. Z comes in being all like, “Now we’re being 3D!”
So wherever the “floor” is, represented with gridlines, boundary, canvas, etc. that’s where they live. That is Flatland where there is no up or down. It is 2D where most of my work is. If you try tell me Y is Z, I’d ask “wtf is a Z?”
Only in a top-down perspective. Most screens are vertically oriented though, meaning the reference 2D plane is left-right-up-down.
You’re mixing up perspective with the object’s actual coordinates system. The “left-right-up-down” are your perspective or computer screen and do not define the axes of the object itself. The object has its own.
If I rotate a map on a table, it’s X and Y don’t suddenly flip. The coordinates belong to the object, I’m just viewing them from a different perspective now.
In mathematics, the Z axis only exists because it’s defined as being perpendicular to an existing plane (the plane X and Y form). The gridlines represent that plane and Z’s extrusion values reference it. Your perspective or viewing angle don’t influence these coordinates at all.
Commonly we face the XY plane down as it’s “floor”. We build things from the ground up. We draw from top down. It’s just how gravity brought the standard around. You can flip it however you want, though. But if you see a grid, that’s a plane and Z is extrusion off that.
By your own logic there is no “up”, only x/y/z, so what’s your complaint?
There is NO mathematical or physical reason why XY should be the floor, that is your own bias.
No. That is not my logic. It’s the logic of Rene Descartes who invented the thing you are trying to talk about.
And because gaslighting attempts online are hilarious, I’ll assume you just didn’t read so good and will repeat myself again; we tend to rest the plane on the floor, as it is in our reality with gravity it is easier to conceive. Like modelling a car, it’s wheels on the screen spend most of the time pointed down.
You don’t have to. You can model it any direction you want, but most people find it easy in an orientation that mimics common perspective. But however you do it, you still can’t have a Z axis without a plane. That’s the point. Grid is plane and plane is needed for Z. If you have a grid on Z it’s representing an infinitely possible slice through extrusion and that’s basically a concept behind some fractals, which introduces a new vector for new XYZ points within.
I know you really want to be right but this is very long-standing foundational and basic stuff we just do. It isn’t my logic or opinion, I’m sharing this knowledge to you, something you can very easily look up yourself right now and forget I even exist—which would be neat.
But what if instead of adding a third dimension by going UP, you add a third dimension by going FORWARD. Like a computer screen, X and Y coordinates are side-to-side and up-and-down. If you made a volumetric display by adding a third dimension to that, Y would be up and Z would be forward.
I usually think of Z as up, because that’s how stuff based on the physical world usually works. But I can understand why some think of it with Y as up.
There are three kinds of people…
Actually…
I’m not getting left handed vs right handed. Right handed means negative values go right? Why would anyone do that?
Right handed means that when you curl the fingers on your right hand from +X towards +Y, your thumb points towards +Z.
Someone else was explaining how to tell left from right handed. Buy why is it important? If you do math and physics, you almost certainly would use a right hand system. That means all formulas are derived with that in mind. If you try to use them in the left handed system, you are going to have a horrible time trying to figure out which of all terms need to have their sign flipped.
Eh sort of? It’s all a matter of perspective. In Blender which uses a right hand system, when you view from the side, right is positive Y, up is positive Z, and towards the user is positive X.
But looking from above, positive X is right, positive Y is up, and positive Z is towards the camera. Obviously if you rotate the camera to be viewing from the negative side of the axis some directions get flipped.
Basically if you’re axis aligned, things work out the way you would expect.
But then should the little axis depictions in OP be swapped?
Yeah the first one is a left handed coordinate system.
Invalid diagram. FreeCAD demands representation.
Oh dear Lord.
Also Minecraft in Y-Up
Unreal Engine is switching to Y-up
Thank god, this is the one true coordinate system
Personally I feel limited if I’m working in anything else than a non-euclidean coordinate system
That’s…not the problematic part there, like at all.
There’s a problematic part ?
A left handed coordinate system is absolte blasphemy.
ah ! well. I don’t use any of the programs that are left handed so I can’t say I’ve ever had to struggle with I/O shenanigans, if that’s what you’re talking about. But you’re leaving me guessing, so not sure what else I can say
unreal georg is an anomaly and should not be counted
Dwarf Fortress goes with Blender and the others
Z up all the way because my 3d printer but why is Minecraft y-up D:
I may be wrong, but I believe mc Java is left handed and bedrock is right handed, both with Y as height
One question, why left handed? The physics would need to be rewritten in the left-handed paradigm, for anything more complicated than simple local behavior simulations, like collisions, constant gravity, etc. A single charged particle in a B and E field would be hell hahaha. Edit: I think it would be adding one - sign at the x.
I know that these more “advanced” simulations wouldn’t normally appear in a game, but they would be a lot harder, and they are effectively the same as fluid and cloth simulation in videogames (just balls and meshs, affected by forces, integrated over time on the gpu).
Tradition, 3d videogames started doing it like that because of how computers worked 40 years ago, then devs got used to think about 3d space that way and it stuck. Essentially videogames think about visual depth. And yes, the physics engines for videogames usually account for that and use their own transformations of formulas because they are rarely simulating anything more complex than rigid body physics. Advanced simulations aren’t any harder for devs, all the transformations are abstracted away with libraries.
In the end they are just reference frames and up is whatever you want it to be. As Wikipedia puts it eloquently: “Unlike most mathematical concepts, the meaning of a right-handed coordinate system cannot be expressed in terms of any mathematical axioms. Rather, the definition depends on chiral phenomena in the physical world, for example the culturally transmitted meaning of right and left hands, a majority human population with dominant right hand, or certain phenomena involving the weak force.”
Yeah, but it would be ctrl c ctrl v on the equations vs getting a lot of - signs for nothing hahaha. Imagine writing the shaders for animations, like explosions, torque, etc, working for cinema 4d, might be a pain in the ass.
Not really. Youtuber Acerola has a great series on shader programming and dealing with negative numbers is a non-factor. The advantage of working with computers is that it abstracts that complexity away. You program with high level concepts, a dev rarely deals with direct calculations, unless they are actually writing the fundamental apis for it, like DX or Vulkan. Much less copy-paste formulas. It gets complicated fast, but the abstraction keeps it simple for the developer, like, the math is perhaps the easiest part of programming computer graphics.
Ace is a decent watch. Shit post quality video energy, that’s information dense. Always gonna second an Acerola suggestion.
Yeah, i was refering to building the fundamental equations, deriving all things in a left handed way and forgetting a - sign.
Like the tensors for building the movement of rigid bodies in a left handed way, calculating jacobians, etc. The - signs start coming and don’t stop coming.
I never built something on these abstractions, just made the equations themselves.
Z always points outwards
My son and I have had this very argument. I think the top one is right as he thinks it’s the bottom one. I have a coding background and he has a 3D printing background. I figure that’s why we’re different but I know nothing about 3D printing beyond the cool stuff I see on the Internet and things he’s printed for me.
Reading this I realized both are correct, for coding the top one, for 3d printing the bottom one.
Somehow the whole thing makes more sense in 3d printing when you move in xy dimension during the layer and z between them.
I have been coding for over 20 years and the bottom one is more correct to me.
X and Y need to be on the same plane.
X and Y are on the same plane in both examples.
Probably because he uses Blender which invert Z and Y axes or maybe because it’s related to the nozzle POV
I have a looking-at-the-chalkboard-in-highschool background which I’m pretty sure defines my perspective(heh).
I have nothing against y pointing up, but I loathe the fact that left-handed coordinate systems are somehow considered an ok choice. This is probably the strongest I feel about something so inconsequential but I’ll die on that hill.
One of my friends and I used to always have this debate because of our different backgrounds. I got used to +Y being up because of doing physics for several years and seeing side-on diagrams that needed to account for gravity. My friend has a background in geology, so he’s used to top-down surveying maps where +Z is up. It all depends on your perspective.
But my way is right. We need to have standards, people.
Knew exactly which one it was before clicking on it
Working with robots at work x is horizontal y is depth z is vertical.
There are two kinds of people: x and x.
<i,j,k> vector master race.
X is up, there now no one is happy.
I’m came here to talk shit about y-up but now I’m mad at you instead.
Getting a 3D printer changed me from the upper to the lower.
Can’t we fix this by using a,b,c coordinates? \s
x in red and z in blue please…, this is difficult to look at. My conventions !
