RE: [Algorithms] interpolate between points in 3d space (correcti on)

[Steve W. <Ste...@im...>]

Oops...forgot to mention...the wind resistance in the Y direction changes
sign after the fodder has started it's way down...so it would be the
opposite sign of the sign of the Y velocity:

Wy = Wy * -sgn(Vy)

Where Vy = Vy0 - g * t

R&R

> -----Original Message-----
> From: Steve Wood 
> Sent: Friday, July 21, 2000 11:48 AM
> To: 'gda...@li...'
> Subject: RE: [Algorithms] interpolate between points in 3d space
> 
> 
> When a projectile is fired you should use it's trajectory 
> equation. It sounds like you are entering the realm of 
> physics. I'll give you a clue, but please pick up a book on 
> newtonion physics, browse the web for physics stuff...there's 
> been many references to physics web sites on this 
> list...unfortunately we don't have an archive that goes back 
> far enough right now that I know of.  Maybe someone will post 
> a link or two for you.
> 
> Anyway for your particular example...let's add a mild 
> constant wind resistance Wz and Wx along Z and X axis:
> 
> X0 = initial X position of fodder after it leaves the cannon.
> Y0 = initial Y position of fodder after it leaves the cannon.
> Z0 = initial Z position of fodder after it leaves the cannon.
> Vx0 = initial velocity in X direction of the fodder after it 
> leaves the cannon.
> Vy0 = initial velocity in Y direction of the fodder after it 
> leaves the cannon.
> Vz0 = initial velocity in Z direction of the fodder after it 
> leaves the cannon.
> Wx = constant wind resistance
> Wy = constant wind resistance
> Wz = constant wind resistance
> g = acceleration of gravity
> t = time with zero when the fodder leaves the cannon.
> 
> X = X0  +  Vx0 * t  -  Wx * t                 //X position
> Y = Y0  +  Vy0 * t  -  Wy * t  -  .5g * t^2   //Y position
> Z = Z0  +  Vz0 * t  -  Wz * t                 //Z position
> 
> That's pretty much it, except you may want to use vector math 
> instead of breaking it up into parts like I did.  Did this 
> answer your question?
> 
> R&R
> 
> > From: Anceschi Mauro [mailto:anc...@li...]
> 
> > Hi.
> > I have a little problem in my 3D space game.
> > When my ship "fire" from a cannon i use a new local axis for 
> > the new object i'm firing , for calculate the next point of 
> the laser.
> > But this works bad, and i  don't have much precision.
> > So my question is:
> > How can interpolate from 2 point in 3d?
> > (x,y,z) and (x',y',z') (suppose the second is an enemy ship).
> >  
> > Thanks,
> >  
> > mauro  
>