RE: [Algorithms] Rendering (a portion of) a Plane (another correc tion)
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From: Steve W. <Ste...@im...> - 2000-07-21 20:04:12
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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 > > > > > > _______________________________________________ > > > GDAlgorithms-list mailing list > > > GDA...@li... > > > http://lists.sourceforge.net/mailman/listinfo/gdalgorithms-list > > > > > > > _______________________________________________ > > GDAlgorithms-list mailing list > > GDA...@li... > > http://lists.sourceforge.net/mailman/listinfo/gdalgorithms-list > > thanks!!!!!!! > > mauro > > > _______________________________________________ > GDAlgorithms-list mailing list > GDA...@li... > http://lists.sourceforge.net/mailman/listinfo/gdalgorithms-list > |