RE: [Algorithms] Rendering (a portion of) a Plane (another correc tion)

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

I'm hoping you caught that the equation I gave:

x^2 + y^2 = distance

should read:

x^2 + y^2 = distance^2


:-<>

R&R

> -----Original Message-----
> From: Anceschi Mauro [mailto:anc...@li...]
> Sent: Friday, July 21, 2000 12:42 PM
> To: gda...@li...
> Subject: Re: [Algorithms] Rendering (a portion of) a Plane
> 
> 
> 
> ----- Original Message -----
> From: "Steve Wood" <Ste...@im...>
> To: <gda...@li...>
> Sent: Friday, July 21, 2000 9:25 PM
> Subject: RE: [Algorithms] Rendering (a portion of) a Plane
> 
> 
> > Hmm,
> >
> > Your equation:
> > Normal[0] * X + Normal[1] * y + Normal[2] * z + distance = 0
> >
> > is defining 3D space as an infinite number of parallel 
> planes with the
> same
> > Normal as in the equation:
> > Normal[0] * X + Normal[1] * y + Normal[2] * z = 0
> >
> > using an index of distance to determine which parallel plane you are
> > referencing.
> > Normal[0] * X + Normal[1] * y + Normal[2] * z = -distance
> >
> > Correct me if I'm wrong, but it sounds like you want to 
> find points ON the
> > plane...if you are trying to describe a circle on the plane 
> then you want
> > all points (x,y,z) which lie on the plane and which are the 
> same distance
> > from your point of origin (x',y',z').  If you like matrices and
> > transformations then perhaps use the 2D (x,y) coordinate 
> plane to find
> your
> > points x^2 + y^2 = distance, then translate and rotate them 
> onto your
> plane.
> >
> > R&R
> >
> >
> > > -----Original Message-----
> > > From: Jeremy Bake [mailto:Jer...@in...]
> > > Sent: Friday, July 21, 2000 6:57 AM
> > > To: 'gda...@li...'
> > > Subject: [Algorithms] Rendering (a portion of) a Plane
> > >
> > >
> > > I've been working on my viewport culling and I just wanted to
> > > test something
> > > out
> > > I was wondering if anyone could tell me how to render a
> > > portion of a plane
> > > around
> > > a particular point using the
> > > Normal + distance version of a plane.
> > > I think it relates to
> > > Normal[0] * X + Normal[1] * y + Normal[2] * z + distance = 0
> > > but I can't seem to get my head around how I could draw 
> this function
> > > over a specific range...  any help would be Greatly appreciated
> > >
> > > Jeremy Bake
> > > RtroActiv
> > >
> > > _______________________________________________
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> > >
> >
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> 
> thanks!!!!!!!
> 
> mauro
> 
> 
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