Re: complex interscetions

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    does anyone know a formula for line intersections through polygons. =
I can do a 2d line intersection and a 3d line intersection, but this is =
hurting my head. Any info would be helpful.
reddager at animalis.com=20


I believe that if you have an equation for each line of a polygon(you =
don't even need endpoints for this part) then you can figure out for =
each line which direction is inside the polygon and which side is out by =
using the > or < symbols.  I remember in simple graphing in algebra I =
class, we would have three equations.  All of these (2D) had a > or < =
instead of an =3D.

Example:
Graph the following:
y < 1/2x + 2
y < -3x + 4
y > -1x - 1

The area in the middle is all that can possibly exist using those three =
equations.  I assume that this would be the same with 3 dimensional =
equations.  I'm not sure exactly how to do this, but I think it's =
possible to use this to figure out if a 3d line intersects a 3d polygon =
made with this method.  I've thought about this already a little, and I =
might more later.  Hope this helps.


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<DIV>&nbsp;&nbsp;&nbsp; does anyone know a formula for line =
intersections=20
through polygons. I can do a 2d line intersection and a 3d line =
intersection,=20
but this is hurting my head. Any info would be helpful.<BR><A=20
href=3D"mailto:reddager at animalis.com">reddager at animalis.com</A> =
<BR></DIV>
<DIV>&nbsp;</DIV>
<DIV>I believe that if you have an equation for each line of a =
polygon(you don't=20
even need endpoints for this part) then you can figure out for each line =
which=20
direction is inside the polygon and which side is out by using the &gt; =
or &lt;=20
symbols.&nbsp; I remember in simple <FONT size=3D3>graphing in algebra I =
class, we=20
would have three equations.&nbsp; All of these (2D) had a &gt; or &lt; =
instead=20
of an =3D.</FONT></DIV>
<DIV><FONT size=3D3></FONT>&nbsp;</DIV>
<DIV><FONT color=3D#000000><FONT size=3D3>Example:</FONT></FONT></DIV>
<DIV><FONT color=3D#000000><FONT size=3D3></FONT></FONT><FONT =
size=3D3></FONT>Graph=20
the following:</DIV>
<DIV>y &lt; 1/2x + 2</DIV>
<DIV>y &lt; -3x + 4</DIV>
<DIV>y &gt; -1x - 1</DIV>
<DIV>&nbsp;</DIV>
<DIV>The area in the middle is all that can possibly exist using those =
three=20
equations.&nbsp; I assume that this would be the same with 3 dimensional =

equations.&nbsp; I'm not sure exactly how to do this, but I think it's =
possible=20
to use this to figure out if a 3d line intersects a 3d polygon made with =
this=20
method.&nbsp; I've thought about this already a little, and I might more =

later.&nbsp; Hope this helps.</DIV>

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