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MathGroup Archive 1998

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Re: Q: Graphics3D

  • To: mathgroup at smc.vnet.net
  • Subject: [mg13441] Re: Q: Graphics3D
  • From: "Allan Hayes" <hay at haystack.demon.cc.uk>
  • Date: Fri, 24 Jul 1998 01:45:30 -0400
  • References: <6p6p5s$5fs@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Jens,
Just a little extra to your suggestion:

>Show[Graphics3D[
>    {{SurfaceColor[RGBColor[1,0,0]],TranslateShape[Sphere[],{1,0,0}]},
>      {SurfaceColor[RGBColor[0,1,0]],TranslateShape[Sphere[],{-1,0,0}]}}
>   ]]

To avoid the spheres showing that the different colors are coming from
lights at different positions (defaults, LightSources
    -> {{{1.,0.,1.},RGBColor[1,0,0]},{{1.,1.,1.},
        RGBColor[0,1,0]},{{0.,1.,1.},RGBColor[0,0,1]}} )

We can, for example,can get the effect of a white light at {1.,1.,1.} by
placing all the light sources at this point:

Show[Graphics3D[
  {{SurfaceColor[RGBColor[1,0,0]],TranslateShape[Sphere[],{1,0,0}]},
    {SurfaceColor[RGBColor[0,1,0]],TranslateShape[Sphere[],{-1,0,0}]}}
], LightSources
    -> {{{1.,1.,1.},RGBColor[1,0,0]},{{1.,1.,1.},
        RGBColor[0,1,0]},{{1.,1.,1.},RGBColor[0,0,1]}}]

Allan,

------------------------------------------------------------- 
Allan Hayes
Training and Consulting
Leicester UK
http://www.haystack.demon.co.uk
hay at haystack.demon.co.uk
voice: +44 (0)116 271 4198
fax: +44(0)116 271 8642



Jens-Peer Kuska wrote in message <6p6p5s$5fs at smc.vnet.net>...
>Hi Ulf,
>
>general to color surfaces You must use the SurfaceColor[] primitive. The
>following shows Your colored spheres:
>
>Show[Graphics3D[
>    {{SurfaceColor[RGBColor[1,0,0]],TranslateShape[Sphere[],{1,0,0}]},
>      {SurfaceColor[RGBColor[0,1,0]],TranslateShape[Sphere[],{-1,0,0}]}}
>   ]]
>
>
>To question (1)
>The default surface color of Mathematica objects is white.  AmbientLight
>is a undirected enviroment light, and if You  look onto a white body
>with a red light it looks red. If You look at a white body with green
>light it looks green.  Thats why You see a red and a green sphere in
>Your a and b graphics. If You combine two graphics objects the options
>for display are taken from the first graphics object. So the
>combination uses the red ambient light of  graphics a and the two white
>spheres look red.
>
>Hope that helps
>  Jens
>-----Original Message-----
>From: Ulf Saalmann <us at mpipks-dresden.mpg.de> To: mathgroup at smc.vnet.net
To: mathgroup at smc.vnet.net
>Subject: [mg13441] [mg13320] Q: Graphics3D
>
>
>>Hello,
>>
>>using the following functions
>>
>>-------------------------------------------------
>>Needs["Graphics`Shapes`"];
>>
>>SetOptions[Graphics3D,LightSources->{}];
>>
>>a=Graphics3D[TranslateShape[Sphere[],{+1,0,0}],
>>             AmbientLight->RGBColor[1,0,0]];
>>b=Graphics3D[TranslateShape[Sphere[],{-1,0,0}],
>>             AmbientLight->RGBColor[0,1,0]];
>>
>>Show[{a,b}];
>>-------------------------------------------------
>>
>>Mathematica shows two red spheres.
>>
>>
>>(1) Why I don't get a red and green one?
>>
>>(2) How to obtain a red and green one (with Lightning->True)?
>>
>>
>>Thanks for any help.    Ulf (us at mpipks-dresden.mpg.de)
>>
>>
>
>



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