# 3-d

``` BBS: Inland Empire Archive
Date: 05-09-92 (10:47)             Number: 68
From: PAUL LEONARD                 Refer#: NONE
To: RICH GELDREICH                Recvd: NO
Subj: 3-d                            Conf: (2) Quik_Bas```
```On or about <May 06 23:21>, Ron Mcdermott (1:272/26) scribbled:

RG>Do you think a book on Analytical Geometry[think that's how
RG>you spell it] would help out?

Yes, it would (and yes, that's how it's spelled, although it's usually called
"analytic geometry").  As someone else posted, you need at
least three equations to solve for three unknowns and he
gave the suggestion of using the dot product of two
vectors.  There are several other equations yuo can use as
well.  One is that the distance between a point
P0(x0,y0,z0) and the plane ax+by+cz+d=0 is given by:

|ax0 + by0 + cz0 + d|
D = =======================
SQRT(a^2 + b^2 + c^2)

You already know D and you can find the equation of the
plane if you have three points in the plane that are not
all on the same line (3 of the corners you defined will
do), so this will give you one more equation of x0,y0,z0 to
work with.

My assumption is that the point in question is either a light source or the
viewpoint to a 3-d surface and that you intend to rotate
effect).  An understanding of vectors in 3-space and 3-D
surfaces & curves would be very useful in applications like
this, so i'd suggest you look around for a college
textbook - most first- & second-year calculus textbooks
cover these topics.  You might also look around for a book
on linear algebra, which covers matrices and their
manipulation (which is how vector products are calculated).

ptl

--- msged 2.07
* Origin: PTL Pointwork (1:105/48.111)
```

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