       Re: plotting plane & a triangle

• To: mathgroup at smc.vnet.net
• Subject: [mg91353] Re: plotting plane & a triangle
• From: MarvelousTau <nightvista at gmail.com>
• Date: Sun, 17 Aug 2008 06:40:26 -0400 (EDT)
• References: <g8685g\$hse\$1@smc.vnet.net>

```On Aug 16, 5:54 pm, skunkwerk <skunkw... at gmail.com> wrote:
> Hi,
>    i'm working on developing some 3d software and I was hoping to use
> mathematica to test the results of some of my code.  Specifically, I'm
> trying to visualize a plane and a triangle, to see if they intersect,
> and if not, which side of the plane the triangle's points are on (I'm
> calculating this using algebra, and need to check the results)
>
> so far I've done:
> (the triangle)
> pl1 = Graphics3D[{Polygon[{{-80.2576, -594.271, 224.043}, {-120.608,
> -588.635, 221.101}, {1.32756, -598.31,261.244}}]}]
>
> (the plane)
> pl2 = Plot3D[0.402395*x - 0.899308*y + 0.171241*z + 274.122 = 0,{x,
> -10000, 10000}, {y, -10000, 10000}]
Plot3D seems cannot plot implicit function. So change it into

pl2 = Plot3D[(0.402395*x - 0.899308*y + 274.122)/0.171241, {x, -10000,
10000}, {y, -10000, 10000}]

and everything goes on well.

>
> then:
> Show[pl1, pl2]
>
> questions:
> 1)  the Polygon is displayed fine on its own, but the plane looks
> completely flat along z=0 and is axis-aligned, so I'm not sure what's
> wrong...
> 2)  the final "Show" command results in a really flat graph that
> doesn't show me anything... do I need to increase or fix the range?
>
> any help would be much appreciated
> thanks
> imran

```

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