TestTubeGames Forums

Posted: **Wed Aug 21, 2013 4:19 pm**

Did you make something really cool in the Gravity Simulator? We want to see it! Post it in this megathread, and we'll check it out.

If you're planning on making a bunch of levels, feel free to start your own, personal thread. Put all your creations in there. Planning on making a *lot* of levels? Then make a few personal threads, grouped by topic (i.e. 'Andy's Cool Gravity Pics', 'Andy's Lagrange Points')

And as always, new threads are totally legit for specific topics or challenges (i.e. 'Make a solar system to scale?', 'Where are the black holes?')

Posted: **Thu Sep 19, 2013 5:41 pm**

Pretty Flower...

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Gravity Fun at TestTubeGames: [ForceG: -2,Qual: 1,Zoom: 0.4,xSet: 0,ySet: 0],[x0: 0,y0: 0,vx: 0,vy: 0,t0: 0,who: 1,m: 30000], [x0: 400,y0: 0,vx: 0,vy: -3,t0: 0,who: 2,m: 10], [x0: 249.39592074,y0: 312.73259299,vx: 2.34549445,vy: -1.87046941,t0: 0,who: 2,m: 10], [x0: -89.00837358,y0: 389.97116487,vx: 2.92478374,vy: 0.6675628,t0: 0,who: 2,m: 10], [x0: -360.38754716,y0: 173.55349565,vx: 1.30165122,vy: 2.7029066,t0: 0,who: 2,m: 10], [x0: -360.38754716,y0: -173.55349565,vx: -1.30165122,vy: 2.7029066,t0: 0,who: 2,m: 10], [x0: -89.00837358,y0: -389.97116487,vx: -2.92478374,vy: 0.6675628,t0: 0,who: 2,m: 10], [x0: 249.39592074,y0: -312.73259299,vx: -2.34549445,vy: -1.87046941,t0: 0,who: 2,m: 10], [x0: 450,y0: 0,vx: 0,vy: -3,t0: 0,who: 2,m: 10], [x0: 280.57041084,y0: 351.82416711,vx: 2.34549445,vy: -1.87046941,t0: 0,who: 2,m: 10], [x0: -100.13442028,y0: 438.71756048,vx: 2.92478374,vy: 0.6675628,t0: 0,who: 2,m: 10], [x0: -405.43599056,y0: 195.2476826,vx: 1.30165122,vy: 2.7029066,t0: 0,who: 2,m: 10], [x0: -405.43599056,y0: -195.2476826,vx: -1.30165122,vy: 2.7029066,t0: 0,who: 2,m: 10], [x0: -100.13442028,y0: -438.71756048,vx: -2.92478374,vy: 0.6675628,t0: 0,who: 2,m: 10], [x0: 280.57041084,y0: -351.82416711,vx: -2.34549445,vy: -1.87046941,t0: 0,who: 2,m: 10], [x0: 500,y0: 0,vx: 0,vy: -3,t0: 0,who: 2,m: 10], [x0: 311.74490093,y0: 390.91574123,vx: 2.34549445,vy: -1.87046941,t0: 0,who: 2,m: 10], [x0: -111.26046698,y0: 487.46395609,vx: 2.92478374,vy: 0.6675628,t0: 0,who: 2,m: 10], [x0: -450.48443395,y0: 216.94186956,vx: 1.30165122,vy: 2.7029066,t0: 0,who: 2,m: 10], [x0: -450.48443395,y0: -216.94186956,vx: -1.30165122,vy: 2.7029066,t0: 0,who: 2,m: 10], [x0: -111.26046698,y0: -487.46395609,vx: -2.92478374,vy: 0.6675628,t0: 0,who: 2,m: 10], [x0: 311.74490093,y0: -390.91574123,vx: -2.34549445,vy: -1.87046941,t0: 0,who: 2,m: 10], [x0: 550,y0: 0,vx: 0,vy: -3,t0: 0,who: 2,m: 10], [x0: 342.91939102,y0: 430.00731536,vx: 2.34549445,vy: -1.87046941,t0: 0,who: 2,m: 10], [x0: -122.38651368,y0: 536.2103517,vx: 2.92478374,vy: 0.6675628,t0: 0,who: 2,m: 10], [x0: -495.53287735,y0: 238.63605651,vx: 1.30165122,vy: 2.7029066,t0: 0,who: 2,m: 10], [x0: -495.53287735,y0: -238.63605651,vx: -1.30165122,vy: 2.7029066,t0: 0,who: 2,m: 10], [x0: -122.38651368,y0: -536.2103517,vx: -2.92478374,vy: 0.6675628,t0: 0,who: 2,m: 10], [x0: 342.91939102,y0: -430.00731536,vx: -2.34549445,vy: -1.87046941,t0: 0,who: 2,m: 10], [x0: 600,y0: 0,vx: 0,vy: -3,t0: 0,who: 2,m: 10], [x0: 374.09388112,y0: 469.09888948,vx: 2.34549445,vy: -1.87046941,t0: 0,who: 2,m: 10], [x0: -133.51256037,y0: 584.95674731,vx: 2.92478374,vy: 0.6675628,t0: 0,who: 2,m: 10], [x0: -540.58132074,y0: 260.33024347,vx: 1.30165122,vy: 2.7029066,t0: 0,who: 2,m: 10], [x0: -540.58132074,y0: -260.33024347,vx: -1.30165122,vy: 2.7029066,t0: 0,who: 2,m: 10], [x0: -133.51256037,y0: -584.95674731,vx: -2.92478374,vy: 0.6675628,t0: 0,who: 2,m: 10], [x0: 374.09388112,y0: -469.09888948,vx: -2.34549445,vy: -1.87046941,t0: 0,who: 2,m: 10], [x0: 650,y0: 0,vx: 0,vy: -3,t0: 0,who: 2,m: 10], [x0: 405.26837121,y0: 508.1904636,vx: 2.34549445,vy: -1.87046941,t0: 0,who: 2,m: 10], [x0: -144.63860707,y0: 633.70314292,vx: 2.92478374,vy: 0.6675628,t0: 0,who: 2,m: 10], [x0: -585.62976414,y0: 282.02443043,vx: 1.30165122,vy: 2.7029066,t0: 0,who: 2,m: 10], [x0: -585.62976414,y0: -282.02443043,vx: -1.30165122,vy: 2.7029066,t0: 0,who: 2,m: 10], [x0: -144.63860707,y0: -633.70314292,vx: -2.92478374,vy: 0.6675628,t0: 0,who: 2,m: 10], [x0: 405.26837121,y0: -508.1904636,vx: -2.34549445,vy: -1.87046941,t0: 0,who: 2,m: 10],

Posted: **Sat Sep 21, 2013 3:23 pm**

this is my 2nd system made (ie just playing around working out the controls still) and it draws a 'rectangular' orbit!?
Gravity Fun at TestTubeGames.com: [ForceG: 1.5,Qual: 1,Zoom: 0.71,xSet: -253.85,ySet: -1175.05], [x0: 218.9,y0: 1099.71,vx: 0,vy: 0,t0: 1.8,who: 2,m: 100], [x0: 221.8,y0: 1167.54,vx: 0,vy: 0,t0: 279.9,who: 3,m: 0], [x0: 453.74,y0: 1012.92,vx: 0,vy: 0,t0: 643.5,who: 1,m: 1000], [x0: 67.18,y0: 1331.59,vx: 0,vy: 0,t0: 1096.2,who: 1,m: 1932], [x0: 193.52,y0: 1386.28,vx: 0,vy: 0,t0: 1190.7,who: 1,m: 1932], [x0: 406.59,y0: 1482.51,vx: 0.62,vy: 8.32,t0: 1575.9,who: 2,m: 394], [x0: 477.58,y0: 1013.73,vx: 0,vy: 0,t0: 2547,who: 1,m: 1932]

Posted: **Mon Sep 23, 2013 7:08 pm**

Flower in a circle:

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Gravity Fun at TestTubeGames.com: [ForceG: -2,Qual: 1,Zoom: 0.8,xSet: 0,ySet: 0], [x0: 0,y0: 0,vx: 0,vy: 0,t0: 0,who: 1,m: 1000], [x0: 200,y0: 0,vx: 0,vy: -2.25,t0: 0,who: 2,m: 10], [x0: 61.80339887,y0: 190.21130326,vx: 2.13987716,vy: -0.69528824,t0: 0,who: 2,m: 10], [x0: -161.80339887,y0: 117.55705046,vx: 1.32251682,vy: 1.82028824,t0: 0,who: 2,m: 10], [x0: -161.80339887,y0: -117.55705046,vx: -1.32251682,vy: 1.82028824,t0: 0,who: 2,m: 10], [x0: 61.80339887,y0: -190.21130326,vx: -2.13987716,vy: -0.69528824,t0: 0,who: 2,m: 10], [x0: 33.19,y0: 138.62,vx: 0.83,vy: -2.28,t0: 19,who: 3,m: 0]

Posted: **Tue Sep 24, 2013 11:59 am**

David, very neat! The first flower basically conquered my CPUs, but did slowly creep along... and was a neat drawing. With the second one you made, I was surprised how well you hit the timing! That asteroid just kept finding those planets at the right moment. Trial and error, or did you have a trick?

Branny, whoa -- rectangular orbits indeed! (((You were using a r^-1.5 force law, which is slightly different than gravity in our normal realm. The strength of gravity doesn't drop off as fast when objects get far apart... so gravity stays fairly strong even at larger distances.))) Edit (thanks to exfret): whoops, you had a r^1.5 law. So the strength of attraction actually *grows* the further away two objects get. My bad!

Apparently in that world, planets would move in a curious way -- drawing almost-ellipses and precessing around to make a box! If you want to see another weird orbit, check this one out:

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Gravity Fun at TestTubeGames.com: [ForceG: 100,Qual: 1,Zoom: 1,xSet: 9,ySet: -3], [x0: 0,y0: 11,vx: 0,vy: 0,t0: 0,who: 1,m: 1000], [x0: 56,y0: 32,vx: 0.3,vy: -3.8,t0: 0,who: 3,m: 0]

There, the force law goes as r^100. Which means, the further away two objects are, the stronger they pull (by a lot!). And since the exponent is so big, this change happens very suddenly, from weakly-pulling to massively-strongly-pulling!

Posted: **Tue Sep 24, 2013 5:18 pm**

I want to say I did some nasty math -- but it was just a happy accident that I refined to be stable.

Posted: **Tue Sep 24, 2013 5:30 pm**

Ummm... Andy, it was a r^1.5 force law, not a r^-1.5. Also, I did notice this when I first started playing the simulator. In fact, it reminded me of some parametric graphs (which was quite interesting). Here: http://fooplot.com/#W3sidHlwZSI6MiwiZXF ... oxMDAwfV0-
You see, it's made from cosines and sines, but it somehow forms a 'rectangular' shape. If you don't know what parametric is, basically, instead of having a single equation where you plug in each x value to find the corresponding y value, you plug in a new variable, s, for each equation for x and y and find the corresponding point. For example, if you plugged in s=2 into x=s^2 and y=3^s, then x=2^2=4, and y=3^2=9, so the point (4,9) would be on the graph. This would then continue on the graph just like it does for getting the values of a function from an expression involving x. The reason why the shape in the gravity simulator isn't all perfect, is because the ratio of the y speed to the x speed isn't very 'simple'. It's some strange ratio, like 7.658/3.597. For example, change the coefficients on the s in the cosine and in sine to something strange like 4.5 and 2.9, then it'll fill up because it takes a really long time for them to match up and repeat the sequence again. The strange things I find about this are the fact that it involves cosines and sines, and that they form a rectangle.

Posted: **Wed Sep 25, 2013 4:43 pm**

A flower in a circle with 3 orbiting bodies. This was completely trial and error. I'm sure there's a mathematical way of arriving there since it seem that it's not a coincidence that the perigee of the "flower" asteroid's orbit is in-line with a planet and the sun every time.

Code: Select all

Gravity Fun at TestTubeGames.com: [ForceG: -2,Qual: 1,Zoom: 0.8,xSet: 0,ySet: 0], [x0: 0,y0: 0,vx: 0,vy: 0,t0: 0,who: 1,m: 1000], [x0: 200,y0: 0,vx: 0,vy: -2.2445,t0: 0,who: 2,m: 10], [x0: -100,y0: 173.20508076,vx: 1.94379402,vy: 1.12225,t0: 0,who: 2,m: 10], [x0: -100,y0: -173.20508076,vx: -1.94379402,vy: 1.12225,t0: 0,who: 2,m: 10],[x0: 100,y0: -0,vx: -1.7,vy: -3.32,t0: 0,who: 3,m: 0]

Posted: **Thu Sep 26, 2013 11:59 am**

exfret wrote:Ummm... Andy, it was a r^1.5 force law, not a r^-1.5.

Also, I did notice this when I first started playing the simulator. In fact, it reminded me of some parametric graphs (which was quite interesting). Here: http://fooplot.com/#W3sidHlwZSI6MiwiZXF ... oxMDAwfV0-

Whoops, yup, you're right! It was r^1.5. My B!

Ah, the connection to that graph makes a lot of sense. Sines and Cosines are hugely important in orbits -- in fact in a r^1 force law, an object moves in a very sine-ular orbit. The x and y positions at any time are governed very basically by sines or cosines (there are two independent equations to worry about, just like in your link, since the object moves in two dimensions). The orbit in r^1 is closed, meaning it loops back on itself, because the two sine functions have the same period.

In r^1.5, the periods aren't the same, and the orbits aren't closed.

I suppose it makes sense it traces out a rectangle, though. After all, each direction (x,y... or whatever axes fit the orbit) has a certain maximum and minimum position. (sine wiggles between -1 and 1) If the asteroid is allowed to explore the whole space* with max/min positions defined in two directions like that, you'll eventually fill the rectangle... and certainly never go outside it.

*How much it can explore, I guess, depends on the relation between the periods. If they're equal, then it just makes a single ellipse... so not much exploration of the space!

Posted: **Thu Sep 26, 2013 5:00 pm**

testtubegames wrote:sine-ular

The word you are looking for is sinusoidal.

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