Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Making Minecraft Spherical

bowerbyte.com

Post reply on HN
Print view View original

111–120 of 130 posts

Re: Making Minecraft Spherical

#111

Post by LeifCarrotson »

harvie wrote: post #107

I was recently thinking about this... We've been building houses and other structures using plum lines and water levels all the time before afordable optics came in play. This kinda means most of our buildings are actualy polar rather than cartesian. Surely enough given the size of earth the error is quite tiny. But it's funny thinking about how the room i am sitting in right now is shaped like frustum with spherical…

If the floor and ceiling (and walls) were leveled and flattened and brought to plumb with a straightedge scraped in with the three-plate method [1] (Popularized by Whitworth in the 1830s, but the ancients made straight edges and flat plates too), then they were actually not 90 degrees at the corners!

[1] https://ericweinhoffer.com/blog/2017/7/30/the-whitworth-thre...

Re: Making Minecraft Spherical

#114

Post by jameshart »

brokensegue wrote: post #109
harvie wrote: post #107

I was recently thinking about this... We've been building houses and other structures using plum lines and water levels all the time before afordable optics came in play. This kinda means most of our buildings are actualy polar rather than cartesian. Surely enough given the size of earth the error is quite tiny. But it's funny thinking about how the room i am sitting in right now is shaped like frustum with spherical…

i imagine imperfections in construction dominate this effect

If you have two buildings 4km apart (about the length of Central Park), that’s about 1/10,000 of an earth circumference so 0.036° change in ‘up’. If the buildings are 300m tall, 300*sin(0.036°) = 0.188m

That’s less than those buildings are probably expected to sway in a strong wind, but probably outside the tolerances for modern construction so theoretically measurable as an average deviation.

Re: Making Minecraft Spherical

#116

Post by Filligree »

b3lvedere wrote: post #104
reactordev wrote: post #13

Earlier quoted context omitted.

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.

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.

Re: Making Minecraft Spherical

#117

Post by UltraSane »

harvie wrote: post #107

I was recently thinking about this... We've been building houses and other structures using plum lines and water levels all the time before afordable optics came in play. This kinda means most of our buildings are actualy polar rather than cartesian. Surely enough given the size of earth the error is quite tiny. But it's funny thinking about how the room i am sitting in right now is shaped like frustum with spherical…

There are very long and narrow wave pools used for research and testing and they are long enough that the surface of the water curves measurably vs extending perfectly straight lines from the center out.

Re: Making Minecraft Spherical

#118

Post by reactordev »

chii wrote: post #96
hdjrudni wrote: post #95

Earlier quoted context omitted.

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…

Correct. Gravity would be net zero but the pressure would be the entire worlds oceans.

Re: Making Minecraft Spherical

#120

Post by [deleted] »

crazygringo wrote: post #56
scotty79 wrote: post #45

Why can't you cover spherical surface with quads so that 4 lines meet at every vertex? How would the proof of that look?

> If you want only quadrilaterals, and you want most vertices to be a meeting between 4 quadrilaterals, but some places 3 quadrilaterals meet, you can use the Euler characteristic to deduce that there must be 8 of these degenerate vertices. https://math.stackexchange.com/a/4904806

[deleted]
Post reply on HN