why why why (lemmy.world)
submitted 9 months ago by hairinmybellybutt to c/[email protected]
top 43 comments
sorted by: hot top controversial new old
[-] croobat 82 points 9 months ago* (last edited 9 months ago)

I found this handy reference a while ago. But yeah, we are kinda screwed.

[-] shotgun_crab 20 points 9 months ago

At least they haven't invented X up (yet)

[-] hairinmybellybutt 24 points 9 months ago

You'll never believe my startup idea

[-] [email protected] 4 points 9 months ago

Dude you totally stole that idea from me, now you owe me half

[-] [email protected] 3 points 9 months ago

There's only one quadrant of this that should be acceptable to anyone! Positive X, positive Y!

[-] [email protected] 6 points 9 months ago

Nope, the bottom right quadrant is the acceptable one. Z is up and follows the right-hand rule. I will die on this hill.

[-] [email protected] 5 points 9 months ago

you'll get bitten during projection when depth is converted to 2D screen coordinates, which is X and Y. Better do it right from the start.

[-] Widowmaker_Best_Girl 2 points 9 months ago

Minecraft ruined me as a kid. I'm still mad that so many softwares use Z as up. I'm still not happy about it.

Y up feels much more comfortable for me.

[-] [email protected] 5 points 9 months ago

Y up is also the standard in 2D graphs, so it makes sense that Z is depth.

[-] [email protected] 1 points 9 months ago

I don't think anyone got my joke 🤷

[-] croobat 1 points 9 months ago

Let's die together chief

[-] [email protected] 16 points 9 months ago

I work in 3D metrology and the consensus is right handed and Z up. Had no idea left handed existed!

[-] [email protected] 4 points 9 months ago

How does projection work in your field? X, Y, Z get converted to X, Z and 2D screen planars have no Y axis?

Who invented this, why did she do it and where to send my official letter of complaint?

[-] [email protected] 5 points 9 months ago

I thought right-hand rule with Z up as thumb was standard in science? You usually project on the xy-plane, for example when calculating the distance to objects on a flat surface.

[-] [email protected] 2 points 9 months ago

I only know thumb = motion/current but now since you say, it's clear: people used x/y for 2D logically but the 2D plane used to be paper. which is parallel to the earth surface (usually). Computer screens are perpendicular so Y points up, not away from you.

So this makes sense with paper, TIL. With computers, Z traditionally means depth.

[-] [email protected] 1 points 9 months ago

TBH I'm not sure I totally understand the question but projection is very useful to decompose the orientation of elements, like a cylinder that you just measured with a machine or a scanner. The coordinates and orientation (angles) can be projected in the three main planes XY, YZ and ZX.

[-] [email protected] 2 points 9 months ago* (last edited 9 months ago)

Sorry for being unclear, I was talking about screen projection. For actual visualization.

[-] [email protected] 3 points 9 months ago

This can happen if you accidentally pilot your player character into a singular linear transformation.

[-] RedditRefugeeTom 9 points 9 months ago

Ugh, when I have to open CAD for a project at work I have to setup a new coordinate system with Z going up, every time. The engineers just work with Y up for some reason. Too lazy to change it perhaps? Solid works and Inventor default Y up? I'll never understand it. I definitely understand this meme. There's also models with an origin 10 feet off in X and 20 feet out in Y. I just do not friggin get it man.

[-] [email protected] 15 points 9 months ago

Because math works with Y up. Physics steal from math, engeneering steals from physics, so, here you are.

What I can't get is imperial measurement system. Apparently, nobody but americans can. And that stuff is far worse than Y and Z switching places.

[-] [email protected] 7 points 9 months ago

as a minecraft player learning how to use autocad, i thought y up was alot more ubiquitous then it apparently is

[-] Widowmaker_Best_Girl 3 points 9 months ago

That's what I don't get. Why would they make Z up when in algebra, Y is up. It's all based on math, shouldn't we keep consistent on that?

[-] [email protected] 2 points 9 months ago

Because the z axis is represented as an extension of the xy-plane, coming out of the paper essentially, so we represent it as up

[-] [email protected] 1 points 9 months ago

That's not true though. While there isn't a standard, convention is to have z up in mathematics, as z is extending the xy plane we normally work with into a third space.

[-] [email protected] 3 points 9 months ago

Might depend on where you were learning.

On paper, when I was learning Descartes' coordibate system, we used Y as up and X as left-right. And when it was time to plot in 3D, we used Z to "extend" the plane into yourself and away from yourself.

You just hold your sheet of paper perpendicular to the ground (or just use a whiteboard) and it all makes sense.

[-] [email protected] 1 points 9 months ago

What I can't get is imperial measurement system. Apparently, nobody but americans can

I'm not American but I've been living in the USA for ten years and I still have trouble with imperial measurements. It's painful dealing with fractions of an inch instead of millimeters.

[-] amanaftermidnight 4 points 9 months ago* (last edited 9 months ago)

CAD used to be digital abstraction of the physical media that is 2D drawings on paper, so XY is the plane of the paper going horizontal/vertical, and most detailing are in vertical cross sections so Y ended up being up most of the time.

The Z axis is then Frankensteined into the existing system to get a proper 3D representation, so it became the depth axis for the existing XY plane.

In Minecraft it's even more evident as Notch Frankensteined the Z axis into a game engine that's originally developed for side scrolling.

[-] [email protected] 3 points 9 months ago

In which world should Z point up and Y represent depth?

Totally crazy opposite world, where cats hunt dogs and rain goes up? This is plain evil...! :-)

[-] MooseBoys 8 points 9 months ago

Nobody commenting on the chirality difference…

[-] [email protected] 8 points 9 months ago* (last edited 9 months ago)

It gets more cursed the more you look at it:

  • you have to convert the coordinate axes (swap z,x,y)
  • then you find out the right/left handed is flipped
  • now your brain melts if you even try think how to solve this with transformation/rotation, what ever.
[-] [email protected] 8 points 9 months ago

It’s called the theory of Gravity after all

[-] Eh_I 5 points 9 months ago

Fuck it, the world is sideways now.

[-] [email protected] 5 points 9 months ago

Because no one can agree what way up is!!

[-] [email protected] 5 points 9 months ago

In robotics I use right hand coordinates with z up. So a car is moving in the 2d xy plane and z is the optional third component. This makes sense to me. For some kind of painting on the screen I can understand why you use y as up. Then again, I know these as uv-coordinates.

[-] [email protected] 4 points 9 months ago

I feel like the cat's coordinate system needs to be rotated 90° to the right.

[-] [email protected] 1 points 9 months ago

Otherwise its still hovering

[-] TurretCorruption 3 points 9 months ago

And this is why you always export for the software you intend to use it in.

[-] Tabboo 2 points 9 months ago
[-] amanaftermidnight 1 points 9 months ago

I feel this meme in all of my rigged bones

[-] [email protected] 1 points 9 months ago

Just label them up, north, east instead of x,y,z

load more comments
view more: next ›
this post was submitted on 06 Jul 2023
725 points (98.8% liked)

Programmer Humor

30604 readers
1067 users here now

Post funny things about programming here! (Or just rant about your favourite programming language.)


founded 4 years ago