Because a flat surface is an x-y plane. The ground is a “flat” surface, and so the z dimension is height.
For me, that’s the only way that makes sense. But I program robots for a living, so I’m used to dealing with coordinate systems where the flat reference is the ground. Programmers seem to be using the screen as the flat reference. If I were building a game world, I’d probably use z-up convention.
Yeah, it depends on whether you expect the 2D view to be on the floor or on the wall. If it’s on the floor, Z is up. If it’s on the wall, Z is forwards & backwards (depth). Personally I think it being on the wall makes way more sense since we already expect from 2D view that Y is up and down, it feels weird to shift it to forwards & backwards when switching to 3D.
Programmers seem to be using the screen as the flat reference.
In screen coordinates, the origin is the top left corner of the screen, and the Y-axis increases towards the bottom of the screen. So Y still isn’t “up”
His point is that’s where it comes from. In most 3D software as seen in the chart, the XY plane is paralel to the screen, just that Y is up instead of down like in 2D, cut that would be insane if it was like that.
Because a flat surface is an x-y plane. The ground is a “flat” surface, and so the z dimension is height.
For me, that’s the only way that makes sense. But I program robots for a living, so I’m used to dealing with coordinate systems where the flat reference is the ground. Programmers seem to be using the screen as the flat reference. If I were building a game world, I’d probably use z-up convention.
Yeah, it depends on whether you expect the 2D view to be on the floor or on the wall. If it’s on the floor, Z is up. If it’s on the wall, Z is forwards & backwards (depth). Personally I think it being on the wall makes way more sense since we already expect from 2D view that Y is up and down, it feels weird to shift it to forwards & backwards when switching to 3D.
In screen coordinates, the origin is the top left corner of the screen, and the Y-axis increases towards the bottom of the screen. So Y still isn’t “up”
His point is that’s where it comes from. In most 3D software as seen in the chart, the XY plane is paralel to the screen, just that Y is up instead of down like in 2D, cut that would be insane if it was like that.
I’m old enough that I also was exposed to Y-down, and that’s still my default.