How to walk through walls using the 4th dimension [video] • Hacker News Board

Re: How to walk through walls using the 4th dimension [video]

#11

Post by JoeAltmaier » Wed, Aug 27, 2014, 7:46 PM UTC

sp332 wrote: post #7

smtddr wrote: post #2

I've been watching this vid on repeat trying to fully comprehend what's happening. This is another vid trying to explain the same thing - https://www.youtube.com/watch?v=UnURElCzGc0 I really want to believe this is possible and this is how we'll be able to travel far into space. Like how we have to spend time walking around a very long wall when a bird can just fly over it in a fraction of the time, we wouldn't have…

That's not very likely, because you don't have to walk around some kind of obstacle to get to a star. Even as a bird, you still have to travel the full distance to your destination. You could make a shortcut in space, which is called a wormhole. You can either make one using extra dimensions, or in 3 dimensions with negative energy to stabilize it, but neither of those seem to exist. Edit: link https://en.wikipedia.o…

Unless 3d space is 'wrinkled'; in 4D you could travel straight there. Imagine a crumpled sheet - the 2D traveler would have to trace a route through all the convolutions to reach the other end of the sheet. The 3D traveler may only have inches to go. 'A Wrinkle in Time' was a story about this.

Re: How to walk through walls using the 4th dimension [video]

#12

Post by pizza » Wed, Aug 27, 2014, 7:47 PM UTC

foolrush wrote: post #6

sp332 wrote: post #5

Earlier quoted context omitted.

Some rubble fell to the side, along the 4th axis. This is a 4th spatial dimension, not time.

But the fourth dimension is timespace, is it not? At least that was what I gathered from Special and General Relativity and the relativity of simultaneity. X^t, Y^t, Z^t?

When people talk about physics that's what it means. But nothing stops you from making a game with 4 independent axes you can move along.

Re: How to walk through walls using the 4th dimension [video]

#13

Post by foolrush » Wed, Aug 27, 2014, 7:49 PM UTC

sp332 wrote: post #8

foolrush wrote: post #6

Earlier quoted context omitted.

But the fourth dimension is timespace, is it not? At least that was what I gathered from Special and General Relativity and the relativity of simultaneity. X^t, Y^t, Z^t?

This game isn't real life! In the game there are four spatial dimensions, just because the game designer decided to have four.

Which is an awful lot like a 4th dimension. Arguably we are all 4th dimensional travellers, albeit somewhat constrained along one of the axes.

Granted, you had me at “This game isn't real life!”

Re: How to walk through walls using the 4th dimension [video]

#14

Post by anoother » Wed, Aug 27, 2014, 7:49 PM UTC

The game looks fascinating. I'm still trying to get my had around the analogies, but get the feeling that playing the game for real will bring a level of intuition to the experience.

In the meanwhile, can anyone help me out?

In the 2D->3D example, you have one shared axis (Z -- vertical), and an alternating pair for the second axis (X and Y -- horizontal). In effect, from the 2D character's point of view, 'jumping' into the third dimension is just swapping your horizontal axis. Your previous horizontal axis is a vertical section through your current one, and vice versa. As such, when swapping axes, you would expect one 1D line (ie. a 1-pixel-wide vertical band) to be the same before and after the swap.

When going 3D-> 4D, you have 2 shared axes. Your third axis alternates, as before. When switching between your 'third' axes, then, you would expect one entire 2D plane of your perceived world-view to remain the same[1]. This doesn't seem to be the case.

What am I missing?

[1] EDIT: This plane is likely to be a section through some concrete objects, so you won't necessarily have 'seen' it before, though it will have been there.

Re: How to walk through walls using the 4th dimension [video]

#15

Post by sp332 » Wed, Aug 27, 2014, 7:49 PM UTC

JoeAltmaier wrote: post #11

sp332 wrote: post #7

Earlier quoted context omitted.

That's not very likely, because you don't have to walk around some kind of obstacle to get to a star. Even as a bird, you still have to travel the full distance to your destination. You could make a shortcut in space, which is called a wormhole. You can either make one using extra dimensions, or in 3 dimensions with negative energy to stabilize it, but neither of those seem to exist. Edit: link https://en.wikipedia.o…

Unless 3d space is 'wrinkled'; in 4D you could travel straight there. Imagine a crumpled sheet - the 2D traveler would have to trace a route through all the convolutions to reach the other end of the sheet. The 3D traveler may only have inches to go. 'A Wrinkle in Time' was a story about this.

You'd just have to hope that the place you want to go to is wrinkled up so that it's next to you, and not still far away.

Re: How to walk through walls using the 4th dimension [video]

#16

Post by biot » Wed, Aug 27, 2014, 7:51 PM UTC

This is a very interesting way of explaining the 4th dimension by relating it to the difference between the 2nd and 3rd dimensions. However, I think what would really solidify my understanding is to see the 4D level editor.

I'm not sure how truly 4D this world is, but it appears to let you switch between a fixed set of different 4 dimensional positions, each of which has a different 3D representation. Just as a plane in a 3D environment is a 2D slice, a plane in a 4D environment is a 3D slice. You could effectively fake this by imagining a triangular prism (like a cylinder, but triangular instead of round). Each face of the prism contains a fully defined 3D world. Switching to the alternate face of the prism is effectively doing the swap to the other 4th dimension, where you can walk along the alternate 3D environment to avoid the obstacle, then switch back to the original 3D environment.

Re: How to walk through walls using the 4th dimension [video]

#17

Post by SerpentJoe » Wed, Aug 27, 2014, 7:52 PM UTC

foolrush wrote: post #6

sp332 wrote: post #5

Earlier quoted context omitted.

Some rubble fell to the side, along the 4th axis. This is a 4th spatial dimension, not time.

But the fourth dimension is timespace, is it not? At least that was what I gathered from Special and General Relativity and the relativity of simultaneity. X^t, Y^t, Z^t?

Whatever you decide "the" fourth dimension "is" (what's the first? second? third?), it doesn't stop someone else from imagining a world with an additional spatial dimension. Relativity does imply a close relationship between time and space but the game world doesn't appear relativistic.

Re: How to walk through walls using the 4th dimension [video]

#18

Post by mordocai » Wed, Aug 27, 2014, 7:53 PM UTC

sp332 wrote: post #15

JoeAltmaier wrote: post #11

Earlier quoted context omitted.

Unless 3d space is 'wrinkled'; in 4D you could travel straight there. Imagine a crumpled sheet - the 2D traveler would have to trace a route through all the convolutions to reach the other end of the sheet. The 3D traveler may only have inches to go. 'A Wrinkle in Time' was a story about this.

You'd just have to hope that the place you want to go to is wrinkled up so that it's next to you, and not still far away.

From my vague recollections they were somehow causing the wrinkles to be close together. It has been years since i've read the series though.

Re: How to walk through walls using the 4th dimension [video]

#19

Post by HeyTyson » Wed, Aug 27, 2014, 7:55 PM UTC

ericHosick wrote: post #4

As a game, this is really cool. But when he got to the 4th dimension it didn't make much sense as an explanation (rubble from 3rd dimension showing up in the 4th). However, if the 4th dimension was time, then you would walk back (or forward) in time to when the wall wasn't there (isn't there anymore cause it is now rubble), move "past the wall", and then walk forward/backward to the original time.

I thought the same until I watched it a second time.

4th dimension is still time. 'The button' takes you to your character's view of moving across a 3rd dimensional plane. I'm assuming the two different textures on the ground represent the change in the 4th dimension (time).

So when you cross to that other side and hit the button again, you're back in the 3rd dimension across a different plane (time). So the desert area is either in the past or in the future (when the wall fell or was being built).

Then he goes through the wall and hits the button again and walks back to his original 3rd dimension.

That's what I took from it anyway. Seems really neat.

Re: How to walk through walls using the 4th dimension [video]

#20

Post by DougWebb » Wed, Aug 27, 2014, 7:58 PM UTC

metadept wrote: post #10

I was really hoping for a continuous (rather than discrete) fourth dimension. The concept is cool and looks to be well executed, but it's not very different from other alternate reality implementations such as the Dark World in Legend of Zelda.

That would be really cool. The mathematics involved don't seem too difficult; you have to add another axis to your vectors, points, and transform matrices, and you can place and orient your models in 4D space, set up lights and a camera in 4D space, and project the camera's view into 3D space first then onto the 2D display. I think the hard part is creating the models and writing the rendering engine. Creating 4D models, rather than just putting 3D models into 4D space, would be hard to wrap your head around. And the tools, both for world creation and for rendering, are almost certainly limited to 3D so you'd have to write your own tools for everything. No more GPU acceleration, unless your 4D to 3D transformation creates models and textures on-the-fly to pass to the GPU.