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Since the question has been answered I'll leave it alone, but I must say
that we JUST went over finding the normal to a plane through a point on
the plane in Linear Algebra last week. I really like a class I can
apply to thinks I enjoy doing.
Steve
Ken wrote:
>
> Yet another 3D Pov math related exersize for the mathmaticaly
> inclined.
>
> A triangle has three coordinates defining the locations of it's three
> corners. Establishing the locations of these is pretty striaght forward
> and follows the standad Pov 3 axis format.
>
> The Challenge:
>
> Given one of the three points is it possible to determine a right
> angle to the third point. A more accurate way of describing this
> is if, as viewed from a -z direction, I had a triangle whose two
> bottom points (P1 -P2) were at y,0 +/- 1 and it's top point (P3)
> was at y,1 x,0 how would I determine, through using math, how to
> place an object like small cylinder or cone so that it is at a
> right angle to the face of the triangle pointing back towards the
> observer.
>
> object
> P3 O P3 object at right angle
> / \ |====
> / \ |
> / \ | ==> -z
> / \ |
> P1 --------- P2 | P1,P2
>
> The solution as I see it lies with the location of the other two
> corner points in three space and the location of the third in relation
> to that. How to deterime that relation ship is what has me baffled.
>
> A use for this would be to place an object at every vertice of
> a mesh object by storing the vertice locations in an array then
> distributing them with the formula that will hopefully be provided
> and a looping function. I understand there are inherent difficulties
> involved with the initial orientation since there are two faces on
> a trangle and it would be easy for the math to choose the wrong
> normal but that would be a different application related exersize
> that awaits the answer to the first part of the problem.
>
> Any takers ?
>
> Thank you,
>
> --
> Ken Tyler
>
> mailto://tylereng@pacbell.net
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