       Re: Q: Varying colors in Plot3D according to Height

• To: mathgroup at smc.vnet.net
• Subject: [mg55436] Re: Q: Varying colors in Plot3D according to Height
• From: Jeff Bryant <jeffb at wolfram.com>
• Date: Wed, 23 Mar 2005 05:34:46 -0500 (EST)
• References: <200503220851.DAA23758@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

There are a number of ways you can do this.  Using Plot3D, you can
use the following:

Plot3D[{4 Sin[x] + 4 Cos[y], If[4 Sin[x] + 4 Cos[y] > 1,
Red, RGBColor[1, 1, 1]]}, {x, 0, 4 Pi}, {y, 0, 4 Pi},
BoxRatios -> {1, 1, 1/GoldenRatio}, PlotPoints -> 50]

You can get better effects, including easier lighting effects, using
ParametricPlot3D:

ParametricPlot3D[{x, y, 4 Sin[x] + 4 Cos[y],
{EdgeForm[], SurfaceColor[If[4 Sin[x] + 4
Cos[y] > 1, Red, RGBColor[1, 1, 1]]]}}, {x, 0, 4 Pi},
{y, 0, 4 Pi}, BoxRatios -> {1, 1, 1/GoldenRatio}, PlotPoints -> 50]

-Jeff

--------------
Jeff Bryant
Wolfram Research, Inc.

Mark Coleman wrote:

> I am plotting a three-dimension function using Plot3D. I would like to
> highlight the portion of the surface whose height exceeds 1.0 a
> different color or hue than the portion of the surface below 1.0. My
> attempts at using ColorFunction to do this have been less than
> aesthetically pleasing, to say the least. Ideally, I'd like the portion
> below 1.0 to retain the default Mathematica blue shading (I'm using
> Mathematica ver 5.1.1 on a Mac OS X 10.3.8), and perhaps have the portion
> above 1.0 to have a red shading. Any help would be greatly appreciated.
>
> Thanks,
>
> -Mark

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