       Light and surface colors

• To: mathgroup at smc.vnet.net
• Subject: [mg58688] Light and surface colors
• From: Daniele Lupo <danwolf_no_spam_please_ at libero.it>
• Date: Thu, 14 Jul 2005 02:49:15 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

```Hi to everyone.

I've just obtained a Student License of Mathematica, and I'm working in
graphics...

I've created, after a half-day of work, an image representing an ellipsoid,
with a colored surface

When I try to represent it, I must put Ligthing->False to see surface
colors.

I'd like to know if there's a way to obtain a rendered image, in which I
can have both light and surface color, to give a shadow to the figure and
create a more 3D effect.

Thanks for replies.

Below there's the code...

Daniele

--------------------------

<< Graphics`ContourPlot3D`;

a = 7; b = 5; c = 4; r = 1;

ellipsoid = ContourPlot3D[
(x/a)^2 + (y/b)^2 + (z/c)^2 - r, {
x, -10, 10}, {y, -10, 10}, {z, -10, 10},
PlotPoints -> 12,
AspectRatio -> Automatic
];

(*It finds the median point of vertices of a list of a 3D coordinates*)
midpoint[l_] := Apply[Plus, Transpose[l], 2]/Length[l];

(*Function to map in the ellipsoid surface*)
pressure[x_, y_, z_] := x^2 + y^2 + Sin[4z];

(*Color Function*)
color[x_] := Hue[pressure @@ midpoint[x]/50];

(*Rule to change original graphic object*)
colorpolygon = Polygon[coord_] :>
{color[coord],EdgeForm[{}],Polygon[coord]};

(*creation of new, colored ellipsoid*)
coloredellipse = ellipsoid /. colorpolygon;

(*Visualization of the shape*)
(*I'd like to have also the light...*)
Show[coloredellipse, Lighting -> False];

```

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