Re: [Algorithms] cannon physics

[Ben S. <3d...@ar...>]

You know, im not really sure.  What is first order time stepping?

Heres what I do.

Use Lance's formula to calculate velocity and angle.  Then I create a vector
from the values using:

XVelocity = Velocity*cosf(Angle)
YVelocity = -Velocity*sinf(Angle)

Then I do a loop where I step time (is this the same thing your talking
about?)

For Time = 0 to 20 (seconds) Time += 0.5
    MyPoint.x = StartPos.x + XVelocity*Time
    MyPoint.y = StartPos.y + YVelocity*Time+(Gravity*Time^2)/2.0
Next

I continue until either all 20 seconds is used up (never) or until MyPoint.y
is lower than my target (on its way down).

Thanks.

-=ben


----- Original Message -----
From: "Jonathan Henckel" <jhe...@cs...>
To: <gda...@li...>
Sent: Friday, December 12, 2003 9:09 AM
Subject: RE: [Algorithms] cannon physics


>
> > -----Original Message-----
> > From: Ben Siroshton [mailto:3d...@ar...]
> > Sent: Thursday, 11 December, 2003 6:22 PM
> > To: gda...@li...
> > Subject: Re: [Algorithms] cannon physics
> >
> >
> > Bob, Lance,
> >
> > Thanks for your help.  I did manage to get it working,
> > however now I am
> > realizing that I can not fix the height as it doesnt allow me
> > to always hit
> > my target.
>
> Can you be more specific?  It looks to me like Lance's formulas will work
> for all inputs, h>y and h>=ty.  Perhaps your cannon misses because you are
> using first order time-stepping?
>
> John Henckel
>
>
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