Subject:
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Re: algebra help (was "Re: Darth Maul...")
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Newsgroups:
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lugnet.cad.dat.parts
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Date:
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Thu, 28 Dec 2000 03:56:03 GMT
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Viewed:
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1346 times
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In lugnet.cad.dat.parts, Franklin W. Cain writes:
> > I can't remember how to calculate the Z co-ord for a point
> > given that it lies in a known plane (I need this maths
> > so I can place the triangles and quads making up the parts
> > of the pattern on the upper and lower curved surfaces
> > of the face in the right Z position).
>
> I don't know if this will help you,
> but this is how I calculate the formula for the X-vs-Z
> co-ordinates of the top and bottom edges of the quad
> in question (for ex., the quad bordered by the co-ords
> (0,4,-13), (0,1.172,-11.536), (4.415,1.172,-10.658),
> and (4.975,4,-12.010) has a bottom edge defined by
> the line whose endpoints are (0,4,-13) and (4.975,4,-12.010),
> and a top edge whose endpoints are (0,1.172,-11.536)
> and (4.415,1.172,-10.658)). Since both of these lines
> are _horizontal_, they each have no variation in their
> respective Y-value, so they are each a simple line
> to calculate (Z=MX+B). Then, for any specific X-value,
> I find the corresponding Z-values for the top and bottom
> edges, and then calculate the line segment connecting
> these two new points, and *then* I use this new forula
> to calculate the correct Z-value for the corresponding Y-value.
>
> In summation:
> For a given (x,y) point;
> Find the appropriate Quad;
> Determine the Endpoints of the Quad;
> Calculate the X-Z Formulae for the Top Edge
> and the Bottom Edge;
> Find the specific Z-values (for the specific X-value)
> for the Top Edge and the Bottom Edge;
> Using these two points, caluclate the formula
> for the line segment connecting them;
> Use this new formula to calculate the Z-value
> for the (x,y) point.
>
> I hope this helps.
> Franklin
Hi Guys,
I have a spreadsheet that might be of some use. It was created to help find
a point on a 3 point plane. After a few trial runs with it, you will find
yourself using it a lot.
Here is a link to my web page that has a bit of info on it.
http://www.geocities.com/pneaster/lego_todo.htm
It uses Microsoft Excel95+ (As far as I know it does not use any macros.)
There are also a few pages that were modified from Steve Bliss' Rotate
spreadsheet which help with calculating line intersections, basic trig
functions, Circle points for 16 and 64 point circles.
Email me and I will send it to you. (If I get several people asking for it,
I will upload it to my site and provide a link to it.)
Paul
http://www.geocities.com/pneaster/lego_parts.htm (finished parts)
http://www.geocities.com/pneaster/lego_todo.htm (in process)
http://www.geocities.com/pneaster/lego_todo2.htm (planned)
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Message is in Reply To:
 | | algebra help (was "Re: Darth Maul...")
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| (...) I don't know if this will help you, but this is how I calculate the formula for the X-vs-Z co-ordinates of the top and bottom edges of the quad in question (for ex., the quad bordered by the co-ords (0,4,-13), (0,1.172,-11.536), (...) (24 years ago, 27-Dec-00, to lugnet.cad.dat.parts)
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