TestTubeGames Forums

Posted: **Wed Jan 29, 2014 9:44 pm**

import math
output = "Gravity Fun at TestTubeGames: [ForceG: -2,Qual: 1,Zoom: 1,xSet: 0,ySet: 0]"
asteroids = 15
mass = 1000
radius = 100
angleoffset = 15
actualangle = (-angleoffset+90) * 2*math.pi/360
vel = math.sqrt(mass/radius)
period = 2*math.pi*math.sqrt(radius**3/mass)
output = output + ", [x0: 0,y0: 0,vx: 0,vy: 0,t0: 0,who: 1,m: " + str(mass) + "]"
for a in range(asteroids):
 angle = 2*math.pi*a/asteroids
 output = output + ", [x0: " + str(radius * math.cos(angle)) + ",y0: " + str(radius * math.sin(angle)) + ",vx: " + str(vel * math.cos(angle + actualangle)) + ",vy: " + str(vel * math.sin(angle + actualangle)) + ",t0: " + str(period * a / asteroids) + ",who: 3,m: 0]"
print output

http://codepad.org/GhkIUaiS
Any particle launched with a certain velocity and a certain distance relative to a gravity source has the same semi-major axis, and the same orbital period, regardless of the direction it travels.

This code is named after the famous asteroid 3753 Cruithne, and its bean-shaped orbit.

Basic:

Code: Select all

Gravity Fun at TestTubeGames: [ForceG: -2,Qual: 1,Zoom: 1,xSet: 0,ySet: 0], [x0: 0,y0: 0,vx: 0,vy: 0,t0: 0,who: 1,m: 1000], [x0: 100.0,y0: 0.0,vx: 0.818457684354,vy: 3.05452566185,t0: 0.0,who: 3,m: 0], [x0: 91.3545457643,y0: 40.6736643076,vx: -0.494689214077,vy: 3.12334477467,t0: 13.2461176877,who: 3,m: 0], [x0: 66.9130606359,y0: 74.3144825477,vx: -1.72229985328,vy: 2.65210920125,t0: 26.4922353755,who: 3,m: 0], [x0: 30.9016994375,y0: 95.1056516295,vx: -2.65210920125,vy: 1.72229985328,t0: 39.7383530632,who: 3,m: 0], [x0: -10.4528463268,y0: 99.4521895368,vx: -3.12334477467,vy: 0.494689214077,t0: 52.9844707509,who: 3,m: 0], [x0: -50.0,y0: 86.6025403784,vx: -3.05452566185,vy: -0.818457684354,t0: 66.2305884386,who: 3,m: 0], [x0: -80.9016994375,y0: 58.7785252292,vx: -2.45755131261,vy: -1.99008581371,t0: 79.4767061264,who: 3,m: 0], [x0: -97.8147600734,y0: 20.7911690818,vx: -1.43564401526,vy: -2.81761002651,t0: 92.7228238141,who: 3,m: 0], [x0: -97.8147600734,y0: -20.7911690818,vx: -0.165500825251,vy: -3.15794386854,t0: 105.968941502,who: 3,m: 0], [x0: -80.9016994375,y0: -58.7785252292,vx: 1.13325896097,vy: -2.95224052668,t0: 119.21505919,who: 3,m: 0], [x0: -50.0,y0: -86.6025403784,vx: 2.2360679775,vy: -2.2360679775,t0: 132.461176877,who: 3,m: 0], [x0: -10.4528463268,y0: -99.4521895368,vx: 2.95224052668,vy: -1.13325896097,t0: 145.707294565,who: 3,m: 0], [x0: 30.9016994375,y0: -95.1056516295,vx: 3.15794386854,vy: 0.165500825251,t0: 158.953412253,who: 3,m: 0], [x0: 66.9130606359,y0: -74.3144825477,vx: 2.81761002651,vy: 1.43564401526,t0: 172.19952994,who: 3,m: 0], [x0: 91.3545457643,y0: -40.6736643076,vx: 1.99008581371,vy: 2.45755131261,t0: 185.445647628,who: 3,m: 0]

(Turn trails off)

Shows the beaniness a bit more:

Code: Select all

Gravity Fun at TestTubeGames: [ForceG: -2,Qual: 1,Zoom: 1,xSet: 0,ySet: 0], [x0: 0,y0: 0,vx: 0,vy: 0,t0: 0,who: 1,m: 1000], [x0: 100.0,y0: 0.0,vx: 1.58113883008,vy: 2.73861278753,t0: 0.0,who: 3,m: 0], [x0: 91.3545457643,y0: 40.6736643076,vx: 0.330548024243,vy: 3.14495437227,t0: 13.2461176877,who: 3,m: 0], [x0: 66.9130606359,y0: 74.3144825477,vx: -0.977197537924,vy: 3.00750477504,t0: 26.4922353755,who: 3,m: 0], [x0: 30.9016994375,y0: 95.1056516295,vx: -2.11597676822,vy: 2.35003027988,t0: 39.7383530632,who: 3,m: 0], [x0: -10.4528463268,y0: 99.4521895368,vx: -2.88888439225,vy: 1.28621419997,t0: 52.9844707509,who: 3,m: 0], [x0: -50.0,y0: 86.6025403784,vx: -3.16227766017,vy: 3.87254531519e-16,t0: 66.2305884386,who: 3,m: 0], [x0: -80.9016994375,y0: 58.7785252292,vx: -2.88888439225,vy: -1.28621419997,t0: 79.4767061264,who: 3,m: 0], [x0: -97.8147600734,y0: 20.7911690818,vx: -2.11597676822,vy: -2.35003027988,t0: 92.7228238141,who: 3,m: 0], [x0: -97.8147600734,y0: -20.7911690818,vx: -0.977197537924,vy: -3.00750477504,t0: 105.968941502,who: 3,m: 0], [x0: -80.9016994375,y0: -58.7785252292,vx: 0.330548024243,vy: -3.14495437227,t0: 119.21505919,who: 3,m: 0], [x0: -50.0,y0: -86.6025403784,vx: 1.58113883008,vy: -2.73861278753,t0: 132.461176877,who: 3,m: 0], [x0: -10.4528463268,y0: -99.4521895368,vx: 2.55833636801,vy: -1.8587401723,t0: 145.707294565,who: 3,m: 0], [x0: 30.9016994375,y0: -95.1056516295,vx: 3.09317430615,vy: -0.657474495161,t0: 158.953412253,who: 3,m: 0], [x0: 66.9130606359,y0: -74.3144825477,vx: 3.09317430615,vy: 0.657474495161,t0: 172.19952994,who: 3,m: 0], [x0: 91.3545457643,y0: -40.6736643076,vx: 2.55833636801,vy: 1.8587401723,t0: 185.445647628,who: 3,m: 0]

Posted: **Sat Feb 08, 2014 12:41 am**

Huh, I'd never heard of Cruithne or bean-orbits before -- thanks for sharing that. Reminds me that one of the options I'd like to have in the new gravity sim is the ability to make the screen rotate, so you can track orbits like these easier. (You could lock it to the 'sun' and 'earth', and then they'd look stationary and Cruithne would draw the bean)

Looks neat even now, though. I like how in the second one, the asteroids kinda whip around the star.

Posted: **Sat Feb 08, 2014 9:18 am**

Yeah, it sounds like it would be a neat thing. Unfortunately, I have no clue how you'd be able to code it.
I'm sure there's a way, but the only thing I can think of sounds like it would be laggy as could be.

Posted: **Sat Feb 08, 2014 2:42 pm**

robly18 wrote:Yeah, it sounds like it would be a neat thing. Unfortunately, I have no clue how you'd be able to code it.
I'm sure there's a way, but the only thing I can think of sounds like it would be laggy as could be.

(Famous last words) Shouldn't actually be too bad. It'll take a lot of UI decisions -- to make it easy to select/deselect/choose which is the star, etc. But for display purposes, each object would just need one position correction each frame before it's displayed. And the orbit lines would draw based on that screen position. So (hopefully) there'd be no appreciable lag.

TestTubeGames Forums

Cruithne... goes the asteroids?

Cruithne... goes the asteroids?

Re: Cruithne... goes the asteroids?

Re: Cruithne... goes the asteroids?

Re: Cruithne... goes the asteroids?