problem is, how do you express global positions without using a double. sure, at a local scale, th

problem is, how do you express global positions without using a double. sure, at a local scale, the chunking works absolutely fine, but especially to multiplayer, having a global position is pretty important. i thought about ways of trying to get around it but couldn't come up with anything that worked well.

Ttannergooding What real world scenario is there for a `Vector3<sbyte>`?

Kai•10/21/23, 9:44 PM

Console games, small cellular automata, that kind of thing

AAqua problem is, how do you express *global* positions without using a double. sure, ...

tannergooding•10/21/23, 9:45 PM

you specify it as a 2 part system
1 is the coordinate of the cell you're in
2 is the position in that cell

tannergooding•10/21/23, 9:45 PM

often the coordinate of the cell is integer based, and the position in the cell is floating

Maxine•10/21/23, 9:46 PM

tanner is right

tannergooding•10/21/23, 9:46 PM

it makes it highly efficient and works well with proper world chunking systems
oct trees, quad trees, binary space partitioning, ECS, etc

Maxine•10/21/23, 9:46 PM

you store a chunk position and a position within the chunk

AquaOP•10/21/23, 9:46 PM

i managed to get that working at a local scale, but not a global one. i couldn't find a way to make it work well in a server
the problem wasn't the positioning, it was the physics engine

AAqua i managed to get that working at a local scale, but not a global one. i couldn't...

Maxine•10/21/23, 9:46 PM

you wouldn't want ints for that either!

AquaOP•10/21/23, 9:46 PM

you'd need to have separate simulations for each chunk, and then that leads to a whole load of problems for when two chunks overlap

Maxine•10/21/23, 9:47 PM

you need a complex system of constraints

Maxine•10/21/23, 9:47 PM

this is a hard problem

AquaOP•10/21/23, 9:47 PM

yeah. the physics engine was the one thing i couldn't find a solution for

AquaOP•10/21/23, 9:47 PM

everything else worked fine, just not physics

AquaOP•10/21/23, 9:47 PM

any system i came up with had some fatal flaw

AAqua you'd need to have separate simulations for each chunk, and then that leads to a...

tannergooding•10/21/23, 9:47 PM

that's exactly what you want, you explicitly want to run physics based around the center of each chunk
explicitly so you avoid precision problems

and then you handle the edge case of crossing a chunk boundary specially, often by doing a 2 step simulation in those edge cases

Maxine•10/21/23, 9:48 PM

you won't want to run all those simulations on the same thread anyway

Maxine•10/21/23, 9:48 PM

so you have to deal with synchronicity

Kai•10/21/23, 9:48 PM

Well... As long as nothing is bigger than one cell you should be fine

Ttannergooding that's exactly what you want, you explicitly want to run physics based around th...

AquaOP•10/21/23, 9:48 PM

2 step simulation?

tannergooding•10/21/23, 9:48 PM

it results in a highly efficient and precise system, especially for localized data in the users view
and allows some level of error the farther you are away from the user, where less precision is fine because the visual fidelity is already lost

AquaOP•10/21/23, 9:48 PM

stuff i need to look into, i know nothing about physics engines, i just use bepu and hope that it works

AAqua 2 step simulation?

Maxine•10/21/23, 9:49 PM

i think what tanner means is, do one side against a cached copy of the other side, then the other side against the result of the first one

KKai Well... As long as nothing is bigger than one cell you should be fine

AquaOP•10/21/23, 9:49 PM

that was another problem i faced, i made my chunks 1x1x1 because i could, and it gave the most amount of precision
but i realized that it would cause even more problems with the physics engine. the problem is in my game is that it's entirely reasonable for something to be larger than one chunk

AquaOP•10/21/23, 9:49 PM

unless i make the chunks large enough to cause precision problems

KKai Console games, small cellular automata, that kind of thing

tannergooding•10/21/23, 9:50 PM

not understanding these examples. none of these would really be working on a Vector3<sbyte>Vector3<sbyte> in particular
many might work with byte[]byte[] though

AquaOP•10/21/23, 9:50 PM

although i did a fair amount of testing and 20km^3 seemed to not have too many precision problems, and it seems large enough to be the reasonable limit for a single object's size, so i can impose an arbitrary limit that says that something cannot be bigger than 20km in size

MMaxine i think what tanner means is, do one side against a cached copy of the other sid...

AquaOP•10/21/23, 9:50 PM

i see
i think
maybe

AAqua unless i make the chunks large enough to cause precision problems

tannergooding•10/21/23, 9:51 PM

one of the neat things about chunking is that when paired with an oct tree
you can make your chunks as fine or as coarse grained as you like

the entire point, in general, is that you have an overall world center
that entire world exists between [-1, +1][-1, +1]
you then subdivide that and each sub chunk also exists in their own [-1, +1][-1, +1] world space

Ttannergooding not understanding these examples. none of these would really be working on a `Ve...

Kai•10/21/23, 9:51 PM

It's fairly reasonable to have a cell use Vector2<byte>Vector2<byte> in either of those to say where on the screen you are. Assuming a simplistic screen-space 2D world here.
sbyte for offsets.

tannergooding•10/21/23, 9:52 PM

typically you end up with a chunk that is pretty small. In minecraft its 16x16m

tannergooding•10/21/23, 9:52 PM

In Skyrim its about a similar size

Kai•10/21/23, 9:52 PM

(Vector3 also works in automata or maybe as Z index for console games, but irrelevant for this example I think)

Ttannergooding one of the neat things about chunking is that when paired with an oct tree you c...

AquaOP•10/21/23, 9:52 PM

i see

AquaOP•10/21/23, 9:53 PM

hmm. interesting. there isn't much online about chunking so i just rolled my own system which seemed to work. ideally chunks would be relatively small, but since my game allows for things to be literally massive, smaller chunks could cause big problems for those sorts of objects

AquaOP•10/21/23, 9:53 PM

but if there's ways around that then that's great

tannergooding•10/21/23, 9:53 PM

a two step system is effectively one that acknowledges you're crossing the boundaries between two cells
and so you can either allow some minor loss near the edge
you can compute for both cells, and interpolate
you can compute within the realm of the parent chunk in the oct tree
or you can even create a temporary origin between both and recompute to avoid loss

tannergooding•10/21/23, 9:54 PM

often its some kind of minor interpolation to avoid issues, but it often involves slightly more work than the normal physics processing

AquaOP•10/21/23, 9:54 PM

or you can even create a temporary origin between both and recompute to avoid loss

interesting, this did actually cross my mind but i dismissed it as i didn't think it would work, but on second thought i don't see why it wouldn't work

KKai It's fairly reasonable to have a cell use `Vector2<byte>` in either of those to ...

tannergooding•10/21/23, 9:55 PM

byte isn't sufficient for most screen coordinates (or even depth space in the world)
but, that's something that a Point2DPoint2D covers well, and where you can allow explicit conversion to a Vector

tannergooding•10/21/23, 9:56 PM

(not to mention working with byte/sbyte is slow, you really want intint for perf)

AquaOP•10/21/23, 9:56 PM

but it often involves slightly more work than the normal physics processing

doesn't matter how much effort it takes, if it works it works

my big problem was that i couldn't come up with anything that would work, but this has given me some ideas
ill keep researching and coming up with new systems to see if i can get it working. good, performant chunking is absolutely paramount for me

AquaOP•10/21/23, 9:56 PM

cheers guys!

Kai•10/21/23, 9:56 PM

I get the idea about a point type, but I feel like it's more an escape hatch and not really a good solution

tannergooding•10/21/23, 9:57 PM

I don't think its an escape hatch, it's good and proper design

Vectors fundamentally have a length, direction, and can be normalized. Those are core and fundamental operations of the type
and features which an integer can't support

tannergooding•10/21/23, 9:58 PM

Vectors and Points are similar, but different
one is an offset (timespan), while the other is an exact location (datetime)

Kai•10/21/23, 9:59 PM

That's the thing I kind of disagree with. Ie cellular automata. I can absolutely calculate the distance to another cell even in this integer world

tannergooding•10/21/23, 9:59 PM

You can then also expose features on Point, like Distance
in a way that works better and is more efficient for integers
namely, Distance is then the manhattan/taxi cab, rather than euclidean distance

tannergooding•10/21/23, 9:59 PM

i.e. you don't return the hypotenuse, which can't be represented as an integer

tannergooding•10/21/23, 9:59 PM

you return the stepping amount in the x/y direction as a pair

tannergooding•10/21/23, 10:00 PM

which is to say, you return the sides required to compute the hypotenuse

problem is, how do you express *global* positions without using a double. sure, at a local scale, th

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problem is, how do you express global positions without using a double. sure, at a local scale, th