39 ms·

I get interesting results if I draw a figure 8 (or a figure ∞). I wonder if it's treating one of the lobes as having negative density.

by _kst_ 6y ago

taeric 6y ago
If you do the same shape without "crossing" over the lines, it does as you might expect. So, yeah, amusing bug. :D
mkl 6y ago
If you extend the infinity sideways (easy with touch, hard with mouse) it seems to depend on how many lobes there are. 3, 5, or 7 is stable, 4, 6, or 8 is very unstable.
anoncow 6y ago
Figure of 8 icebergs fly off, then sink completely and finally float. Fun stuff. Is the source available? And some of them completely disappear!
- thaumasiotes 6y ago
  Yes, you can see the source just by doing "view source" in the browser. It's nicely commented and everything.
- elc0c0 6y ago
  yeah!!
jzer0cool 6y ago
I draw an ice cream cone. First draw the ice cream like you would a cloud. Once connected then continue to draw the cone , such that you draw a V to connect to the ice cream. It flys!
deleted 6y ago
[deleted]
dheera 6y ago
I think I broke it https://i.imgur.com/WQiLpKb.png https://i.imgur.com/WQiLpKb.png
yibg 6y ago
sailboat apparently also floats like a sailboat would: https://imgur.com/a/2DwYh0j https://imgur.com/a/2DwYh0j
jojobas 6y ago
Funnily, it seems to glitch at the screen edges.
fingerlocks 6y ago
If you draw a bucket or any convex shape it fills with water (via osmosis?) and sinks.
MarkMc 6y ago
This 'bug' actually makes it more interesting and engaging
sgtnoodle 6y ago
The code must somehow compute bouyancy in a way that reflects the object's arbitrarily complex shape. It's likely carving the object up into some number of smaller primitive objects whose equations for bouyancy are known. In order to make the whole object move as one rigid body, though, it's probably computing force vectors for each primitive, and then summing them together based on the overall object's center of mass and moment of inertia. My guess is that the object's mass and inertia is calculated in a way that is sensitive to the handedness of the drawing. The code probably takes the absolute value of the result so that right-handed and left-handed drawings both end up with positive mass. When you draw lobes though, the signedness alternates and cancels out, leading to less mass. With even numbers of lobes of near equal size, you end up with near zero mass. The forces being computed on each primitive are probably representative of that primitive's true mass. Subsequently applying those same forces to a rigid body with significantly less mass therefore results in extreme acceleration. f=ma, f/m=a. f/0=explode.
- sillysaurusx 6y ago
  If anyone wants to do this, you're looking for "approximate convex decomposition": http://codesuppository.blogspot.com/2006/04/approximate-convex-decomposition.html http://codesuppository.blogspot.com/2006/04/approximate-conv... It was one of the grand challenges in the 00's, quietly solved by John Ratcliff. Then a few people solved it after him. It's a fun algorithm. You basically slice and dice, like chopping a potato, then recombine small parts together based on a heuristic.
- arithma 6y ago
  I knew this was happening, but reading it, hey, maybe that's one way to get anti-gravity. Just loop the topology on itself. Obviously commenting in jest, but now I'm intrigued to see if someone has seriously considered this.
  - 5600k 6y ago
    One of the theoretical reverse time travel machines I read about in the past involved stabilizing a wormhole first and then dragging it somewhere else, like to the future relative to current time by traveling near light speed with it, so you could get back to the earlier time. Kip Thorne wrote of something that involved an extreme amount of mass in a spinning cylinder. That kind of mass was imagined to be at a huge scale like harnessing a number of stars and compressing them, iirc. A device theorized or implemented by Salvatore Pais involves use of superconductors and microwaves to create an effective vacuum, like dragging part of spacetime. It could allow FTL relocation without actual speed. This could also create an area of effectively high masses that could allow time travel, even eventually reverse time travel, under theoretical conditions.
maxrmk 6y ago
I spent... longer than I should have trying to take advantage of this bug to recreate a stable version of the stereotypical tall iceberg that the original tweet was complaining about. https://imgur.com/a/WG6D0RJ https://imgur.com/a/WG6D0RJ
- rbobby 6y ago
  From left to right draw a sawtooth shape. Make the last one very wide. Then retrace your steps completing the other half of the sawtooth. https://imgur.com/a/Kb8Y8zv https://imgur.com/a/Kb8Y8zv (there are about 4 completed saw tooths above the screen)
- sgtnoodle 6y ago
  You can create pontoons by circling over the same spot repeatedly. It's like you're concentrating more mass into the same area but reducing the density! https://ibb.co/VmXShfY https://ibb.co/VmXShfY
- rampant_ai 6y ago
  I was able to make sailboats that float if I cross the line over itself so the sail is in "negative space", which keeps it upright. Kinda neat! https://i.imgur.com/2LZn50v.png https://i.imgur.com/2LZn50v.png
  - sgtnoodle 6y ago
    It's prettier than my boat. :-) I believe it works because the sail consists of negative mass. The overall mass of the boat is therefore lower, but the part of the hull that's under water produces the same amount of bouyancy based on the area of displaced water. Because of the width of the hull, it's a stable equallibrium. Interestingly, if the sail were to become submerged, it would create negative bouyancy and the boat would sink!
- deleted 6y ago
  [deleted]
- deleted 6y ago
  [deleted]
croes 6y ago
Fo be fair, this shape is hardly possible for a real iceberg.
- Sharlin 6y ago
  You mean there are no zero-volume nonorientable-manifold Klein bottle icebergs in real life? :(
NiceWayToDoIT 6y ago
Antigravity device :)
- deleted 6y ago
  [deleted]
wruza 6y ago
If you draw death, it often flies intimidatingly across the screen. https://imgur.com/a/bVh5iAt https://imgur.com/a/bVh5iAt Start drawing at trapeze vertex left to the head.
ajuc 6y ago
It's a shame we can't recreate this material in real life :)
ghusbands 6y ago
Given how much the behaviour varies at different angles and in different positions, we can be fairly sure the algorithm used is incorrect even without these odd cases. You can also see odd orientation-dependent behaviours with non-weird shapes.
- 5600k 6y ago
  It’s very good though. To really throw it off and make it stay underwater or hop around, you must be quick to reduce the points and create negative areas via crossover. But it’s impressive how it lets you draw beyond the boundaries and reacts reasonably. Best iceberg simulator I’ve ever used. I had fun playing with it for at least ten minutes. I’d go so far as to recommend it for education.
madprops 6y ago
I tried with a timeglass-like shape. It flew around the map, going in and out of view and eventually setting on/in the water https://i.imgur.com/kcT9elV.jpg https://i.imgur.com/kcT9elV.jpg
t0astbread 6y ago
I think this was patched just now. On my last visit a few minutes ago the bug still worked, now it removes any larger bits where the lines intersect. Also, the code has been amended right where this comment is: // People like to draw shapes with kinks, which results // in part of the polygon being treated as negative area. // turf.unkinkPolygon can be used to find the kinks and // separate the polygon into multiple polygons at the // kinks, but it's a little fragile and hard to combine // into a single unkinked polygon. [...]
- jinseokim 6y ago
  You may want to revert the (tedious) patch about intersections. Here is a simple workaround: > turf.unkinkPolygon=(x)=>x; Press F12, click 'Console', copy-paste the above one and press Enter.
  - Aardwolf 6y ago
    I'm having so much fun with the before-the-fix version, you can make it "jump" out of the water, if you draw a figure 8 under water, and when the negative lobe is at the top and around 75% of the size of the positive one Even more optimal: https://imgur.com/7gCEJ0T https://imgur.com/7gCEJ0T I've had more extreme versions of this shape teleport off-screen, when starting them under water: https://imgur.com/ymVtTWq https://imgur.com/ymVtTWq And here's someone holding a balloon: https://imgur.com/8O4rib8 https://imgur.com/8O4rib8
- crazyKoala2 6y ago
  It still works, you just have to mess around with the lines a bit more: https://gliggy.github.io/broken.png https://gliggy.github.io/broken.png
- dheera 6y ago
  Damnit it was so much more fun before the "fix".
lbblack 6y ago
Symmetric and asymmetric behavior baffles me. Any progressive papers on the independent relationships between infinite limits, finite quantities, and asymmetric phenomenon would be much appreciated from the homestead. Also, what is the dependent relationship between stable states and non-stable state systems? Is it more simple than thought before?

I get interesting results if I draw a figure 8 (or a figure ∞). I wonder if it's treating one of the lobes as having negative density.

by _kst_ 6y ago

I get interesting results if I draw a figure 8 (or a figure ∞). I wonder if it's treating one of the lobes as having negative density.

taeric 6y ago

If you do the same shape without "crossing" over the lines, it does as you might expect. So, yeah, amusing bug. :D

mkl 6y ago

If you extend the infinity sideways (easy with touch, hard with mouse) it seems to depend on how many lobes there are. 3, 5, or 7 is stable, 4, 6, or 8 is very unstable.

anoncow 6y ago

Figure of 8 icebergs fly off, then sink completely and finally float. Fun stuff. Is the source available? And some of them completely disappear!

thaumasiotes 6y ago
Yes, you can see the source just by doing "view source" in the browser. It's nicely commented and everything.
elc0c0 6y ago
yeah!!

jzer0cool 6y ago

I draw an ice cream cone. First draw the ice cream like you would a cloud. Once connected then continue to draw the cone , such that you draw a V to connect to the ice cream. It flys!

deleted 6y ago

[deleted]

dheera 6y ago

I think I broke it https://i.imgur.com/WQiLpKb.png https://i.imgur.com/WQiLpKb.png

yibg 6y ago

sailboat apparently also floats like a sailboat would: https://imgur.com/a/2DwYh0j https://imgur.com/a/2DwYh0j

jojobas 6y ago

Funnily, it seems to glitch at the screen edges.

fingerlocks 6y ago

If you draw a bucket or any convex shape it fills with water (via osmosis?) and sinks.

MarkMc 6y ago

This 'bug' actually makes it more interesting and engaging

sgtnoodle 6y ago

The code must somehow compute bouyancy in a way that reflects the object's arbitrarily complex shape. It's likely carving the object up into some number of smaller primitive objects whose equations for bouyancy are known. In order to make the whole object move as one rigid body, though, it's probably computing force vectors for each primitive, and then summing them together based on the overall object's center of mass and moment of inertia. My guess is that the object's mass and inertia is calculated in a way that is sensitive to the handedness of the drawing. The code probably takes the absolute value of the result so that right-handed and left-handed drawings both end up with positive mass. When you draw lobes though, the signedness alternates and cancels out, leading to less mass. With even numbers of lobes of near equal size, you end up with near zero mass. The forces being computed on each primitive are probably representative of that primitive's true mass. Subsequently applying those same forces to a rigid body with significantly less mass therefore results in extreme acceleration. f=ma, f/m=a. f/0=explode.

sillysaurusx 6y ago
If anyone wants to do this, you're looking for "approximate convex decomposition": http://codesuppository.blogspot.com/2006/04/approximate-convex-decomposition.html http://codesuppository.blogspot.com/2006/04/approximate-conv... It was one of the grand challenges in the 00's, quietly solved by John Ratcliff. Then a few people solved it after him. It's a fun algorithm. You basically slice and dice, like chopping a potato, then recombine small parts together based on a heuristic.
arithma 6y ago
I knew this was happening, but reading it, hey, maybe that's one way to get anti-gravity. Just loop the topology on itself. Obviously commenting in jest, but now I'm intrigued to see if someone has seriously considered this.
- 5600k 6y ago
  One of the theoretical reverse time travel machines I read about in the past involved stabilizing a wormhole first and then dragging it somewhere else, like to the future relative to current time by traveling near light speed with it, so you could get back to the earlier time. Kip Thorne wrote of something that involved an extreme amount of mass in a spinning cylinder. That kind of mass was imagined to be at a huge scale like harnessing a number of stars and compressing them, iirc. A device theorized or implemented by Salvatore Pais involves use of superconductors and microwaves to create an effective vacuum, like dragging part of spacetime. It could allow FTL relocation without actual speed. This could also create an area of effectively high masses that could allow time travel, even eventually reverse time travel, under theoretical conditions.

maxrmk 6y ago

I spent... longer than I should have trying to take advantage of this bug to recreate a stable version of the stereotypical tall iceberg that the original tweet was complaining about. https://imgur.com/a/WG6D0RJ https://imgur.com/a/WG6D0RJ

rbobby 6y ago
From left to right draw a sawtooth shape. Make the last one very wide. Then retrace your steps completing the other half of the sawtooth. https://imgur.com/a/Kb8Y8zv https://imgur.com/a/Kb8Y8zv (there are about 4 completed saw tooths above the screen)
sgtnoodle 6y ago
You can create pontoons by circling over the same spot repeatedly. It's like you're concentrating more mass into the same area but reducing the density! https://ibb.co/VmXShfY https://ibb.co/VmXShfY
rampant_ai 6y ago
I was able to make sailboats that float if I cross the line over itself so the sail is in "negative space", which keeps it upright. Kinda neat! https://i.imgur.com/2LZn50v.png https://i.imgur.com/2LZn50v.png
- sgtnoodle 6y ago
  It's prettier than my boat. :-) I believe it works because the sail consists of negative mass. The overall mass of the boat is therefore lower, but the part of the hull that's under water produces the same amount of bouyancy based on the area of displaced water. Because of the width of the hull, it's a stable equallibrium. Interestingly, if the sail were to become submerged, it would create negative bouyancy and the boat would sink!
deleted 6y ago
[deleted]
deleted 6y ago
[deleted]

croes 6y ago

Fo be fair, this shape is hardly possible for a real iceberg.

Sharlin 6y ago
You mean there are no zero-volume nonorientable-manifold Klein bottle icebergs in real life? :(

NiceWayToDoIT 6y ago

Antigravity device :)

deleted 6y ago
[deleted]

wruza 6y ago

If you draw death, it often flies intimidatingly across the screen. https://imgur.com/a/bVh5iAt https://imgur.com/a/bVh5iAt Start drawing at trapeze vertex left to the head.

ajuc 6y ago

It's a shame we can't recreate this material in real life :)

ghusbands 6y ago

Given how much the behaviour varies at different angles and in different positions, we can be fairly sure the algorithm used is incorrect even without these odd cases. You can also see odd orientation-dependent behaviours with non-weird shapes.

5600k 6y ago
It’s very good though. To really throw it off and make it stay underwater or hop around, you must be quick to reduce the points and create negative areas via crossover. But it’s impressive how it lets you draw beyond the boundaries and reacts reasonably. Best iceberg simulator I’ve ever used. I had fun playing with it for at least ten minutes. I’d go so far as to recommend it for education.

madprops 6y ago

I tried with a timeglass-like shape. It flew around the map, going in and out of view and eventually setting on/in the water https://i.imgur.com/kcT9elV.jpg https://i.imgur.com/kcT9elV.jpg

t0astbread 6y ago

I think this was patched just now. On my last visit a few minutes ago the bug still worked, now it removes any larger bits where the lines intersect. Also, the code has been amended right where this comment is: // People like to draw shapes with kinks, which results // in part of the polygon being treated as negative area. // turf.unkinkPolygon can be used to find the kinks and // separate the polygon into multiple polygons at the // kinks, but it's a little fragile and hard to combine // into a single unkinked polygon. [...]

jinseokim 6y ago
You may want to revert the (tedious) patch about intersections. Here is a simple workaround: > turf.unkinkPolygon=(x)=>x; Press F12, click 'Console', copy-paste the above one and press Enter.
- Aardwolf 6y ago
  I'm having so much fun with the before-the-fix version, you can make it "jump" out of the water, if you draw a figure 8 under water, and when the negative lobe is at the top and around 75% of the size of the positive one Even more optimal: https://imgur.com/7gCEJ0T https://imgur.com/7gCEJ0T I've had more extreme versions of this shape teleport off-screen, when starting them under water: https://imgur.com/ymVtTWq https://imgur.com/ymVtTWq And here's someone holding a balloon: https://imgur.com/8O4rib8 https://imgur.com/8O4rib8
crazyKoala2 6y ago
It still works, you just have to mess around with the lines a bit more: https://gliggy.github.io/broken.png https://gliggy.github.io/broken.png
dheera 6y ago
Damnit it was so much more fun before the "fix".

lbblack 6y ago

Symmetric and asymmetric behavior baffles me. Any progressive papers on the independent relationships between infinite limits, finite quantities, and asymmetric phenomenon would be much appreciated from the homestead. Also, what is the dependent relationship between stable states and non-stable state systems? Is it more simple than thought before?