Making an orbit simulator

[SamPerson12345]

I'm currently working on an orbital simulator based on Newton's gravity equation, where you can set the mass and initial velocities of multiple planets. It's working really well so far, but I would like it if someone would look my code over and make sure it implements the laws of physics properly before I add all of the arrays and loops necessary for this to work. It would also be a great help if someone would give me some tips on optimization, because I'm a bit worried about keeping this efficient enough to calculate the gravity between five or six planets at once.
Here's my code so far:

@name Orbiter
@inputs 
@outputs
@persist Ent:entity GravConstant Pos:vector Vel:vector Mass1 Mass2
@trigger 
if(first()|duped()){
    runOnTick(1)
    holoCreate(1)
    holoCreate(2)
    holoModel(1,"sphere")
    holoModel(2,"sphere")
    holoScale(1,vec(2,2,2))
    holoScale(2,vec(1,1,1))
    Ent = entity()
    GravConstant = 1
    Pos = vec(100,0,100)
    Mass1 = 500
    Mass2 = 1
    Vel = vec(-1,2,1)
}
holoPos(1,Ent:pos()+vec(0,0,100))
Force = (GravConstant*Mass1)/(Pos:distance(vec(0,0,100))^2)
Oldpos = Pos
Pos = Vel+Pos+(vec(0,0,100)-Pos):normalized()*Force
Vel = Pos-Oldpos
holoPos(2,Ent:pos()+Pos)

As soon as I get the loops going, that stationary planet will be able to move.
Any help at all would be greatly appreciated.

[Vbitz]

Very nice work, i am no e2 programmer but i am learning but just look on wikipedia for all your physics related things

Sorry if it is broken but here is the forumla

[Joshieballz]

i made a orbiter.
but i used sin() and cos()

@name Planets
@inputs 
@outputs 
@persist Counter Spin
@trigger all
 
interval(10)
if(first()){
holoCreate(1)
holoCreate(2)
holoCreate(3)
}
 
Spin+=2
Counter++
 
Sinearth = sin(Counter*1.2)
Cosearth = cos(Counter*1.2)
SinMoon = sin(Counter*10)
CosMoon = cos(Counter*10)
 
#Sun
Pos1 = entity():pos() + entity():up()*50
holoPos(1,Pos1)
holoModel(1,"sphere3")
holoColor(1,vec(255,255,0))
holoScale(1,vec(5,5,5))
holoMaterial(1,"debug/debugdrawflat")
 
#Earth
Pos2 = entity():pos() + entity():up()*50 + vec(Sinearth*100,Cosearth*100,0)
holoPos(2,Pos2 )
holoModel(2,"sphere3")
holoColor(2,vec(0,255,150))
holoScale(2,vec(1.2,1.2,1.2))
holoAng(2,ang(0,Spin,0))
holoMaterial(2,"debug/debugdrawflat")
 
#Moon
Pos3 = Pos2 + vec( SinMoon*15,CosMoon*15,0)
holoPos(3,Pos3)
holoModel(3,"sphere3")
holoColor(3,vec(255,255,255))
holoScale(3,vec(0.2,0.2,0.2))
holoAng(3,ang(0,Spin,0))
holoMaterial(3,"debug/debugdrawflat")

[Whosdr]

Is it gravitationally correct?

[SamPerson12345]

Is it gravitationally correct?

That's what I'm trying for. You can edit the values in the expression and it will come up with a different orbit, or the planet may even break free of the sun's gravity.

[Whosdr]

Force = (GravConstant*Mass)/(Pos:distance(vec(0,0,100))^2)
You did *Mass nor *Mass1 or *Mass2

[SamPerson12345]

Force = (GravConstant*Mass)/(Pos:distance(vec(0,0,100))^2)
You did *Mass nor *Mass1 or *Mass2

Yes, I know. I did that because I think the gravitational force would be spread out through all of the mass in the planet, so you only need the mass of what it's orbiting around to find out how the gravity would change the velocity. Also, If I had put in both masses, then objects with different masses would fall at different speeds.

[Solece]

I actually already made a basic orbiter, using props though, not holos. The Source engine pretty much does all the work for me.
Heres the code, feel free to modify it. Just give me some credit.

@name Haloguy's Orbiter
@inputs 
@outputs B
@persist R:array A
@trigger 

interval(1)
E=entity()
O=owner()
Rand=(cos(curtime()*10)*127.5)+127.5
timer("update",500)
if(first()){holoCreate(1)}
if(clk("update")){
    holoScale(1,vec(15,15,15))
    holoModel(1,"sphere3")
findInSphere(E:pos(),100000)
findClipToClass("prop_physics")
findIncludePlayerProps(O)
R=findToArray()
}
holoPos(1,E:pos())
A++
if(A>R:count()){A=0}
Prop=R:entity(A)
Vec=E:pos()-Prop:pos()
Prop:applyForce(Vec*Prop:mass()/600)
holoColor(1,vec(Rand,255-Rand,Rand))
B=R:count()

Note that this was made for spacebuild, so it will only work for props if they have no gravity. You do have to manually throw the prop into orbit though