You should definitely have a look at space engineers. They have a similar spherical problem with their voxels and I don’t think they went half as far as you did when implementing “orbital bodies”.
As someone who is rather keen on space, gfx, and the algorithms that render them. Kudos. The problems were known to me, which is why I didn’t attempt it, however - the distortion correction, the chunking, I’m thinking if you just limit how far down you can dig (half way to the “core”) it will be fine. You won’t run into those tiny squished blocks that make up the core.
It’s also important to call out the quad-sphere. This is what makes it doable. Naive devs may just map lat long to sin cos spherical coordinates and call it a day, not realizing that their poles are jacked up. The cartography problem. I’m really glad to see that called out as people don’t realize WGS84 sucks for mapping a sphere.
> WGS84 sucks for mapping a sphere.
WGS84 is not a map projection, it's a geodetic reference frame prescribing a reference ellipsoid and reference positions of ground stations.
https://en.m.wikipedia.org/wiki/World_Geodetic_System#WGS84
Not allowing excavation to the core solves weird gravity issue as well. Astroneer had super weird gravity at their planet core. You can get stuck oscillating there.
If you really wanted to go for realism, there would be NO GRAVITY at the core. :P
As you dig down you would get lighter and lighter on your feet.
Any mass you are below (within the sphere of Earth) will exert a gravitational pull in one direction, while the mass above you (also within the Earth) will exert an equal and opposite pull.
If earth was just full of water.... as you swam deeper and deeper there would be more and more pressure upon you. Would there be a point where that pressure would start to lessen as the water is pulled in all directions?
> pressure would start to lessen as the water is pulled in all directions?
the pressure would never lessen, just increase slower.
The gravity at the center is zero, but the mass above you is not exerting just gravity force (which gets cancelled out by the opposite side), but also pressure (from the weight of it falling down).
This means the water pressure would steadily climb, but at a slower rate as you move nearer to the center, and will be at maximum at the very center.
Correct. Gravity would be net zero but the pressure would be the entire worlds oceans.
Awesome question!
Yeah, I'm mostly aware of that. Weird didn't mean 'wrong' in this case, just weird for a terrestrial-bound human. :)
There’s all sorts of weird physics in the universe ;)
>As you dig down you would get lighter and lighter on your feet.
Fun fact: Gravity doesn't decrease the entire way down! Only when you get to the core does it decrease monotonically: https://physics.stackexchange.com/questions/18446/how-does-g...
If you REALLY want to aim for realism, gravity should depend on all quads on the planet. So, if you were to build a huge floating island, the gravity between it and the planet would be less than the usual
If you really truly wanted to aim for realism, digging to the core would require a huge budget and an international coalition that would get bogged down in politics and mismanagement and it would never happen.
30 year pension plan.
That's how it's implemented in the game!
Just a thought; I do wonder in reality if there is an actual single physical point that has any form of material but totally zero gravity. I think anything, as longs its size is above the planck length, has some gravity.
If nothing else, your own body will exert some gravity on you.
That actually sounds pretty close to what I would expect to happen IRL. After all the mass is mostly all around you at that point and depending on how far you are towards the core you might build up speed, overshoot the target and then do it all over again.
But hollow planets are hard to come by so this is just my imagination, I'm sure someone has worked out exactly what would happen.
Newton worked this out in what is now know as the shell theorem. If you have a hollow spherically symmetric body, then any point inside of the body experiences no net gravitational force. In contrast, points outside of the shell experience the same force as if the body were a point mass.
For ideal (spherically symmetric) planets where a point is underground, you can divide the planet into 2 regions. The shell of the planet "above" the point has no net effect, while the shell below has the full effect, resulting in the gravity falling towards 0 as you approach the center.
In practice, planets are not actually spherically symmetric, but are close enough for it to be a good approximation.
That's super interesting, thank you for posting this!
I think the outer wilds did this perfectly. I seem to remember falling towards the core and gravity just disappearing.
Astroneer does deliberately make it weirder, though, it's not just a simple gravity implementation.
My understanding is Space Engineers takes the "blocky sphere" approach mentioned early in the post, works around the "walk along its surface" part of the problem by making gravity direction point towards a fixed point, and bypasses the "trying to build 'upward'" part of it by not allowing voxel construction. It doesn't use a quad-sphere at all.
Correct, which is why I said they didn’t go half as far as the OP did. Most stop at quadsphere after realizing their blocks are no longer square.
Everyone wants to dig to the core (and build a cool zero g habitat there), at least that was the first thing I did :)
thats why a liquid core is needed in the matrix
Curious about this, is there actually a canonical explanation in the trilogy somewhere?
no, i was just kidding :D