Re: Can Mathematica draw overlapping shapes with blended color?

• To: mathgroup at smc.vnet.net
• Subject: [mg28996] Re: Can Mathematica draw overlapping shapes with blended color?
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Thu, 24 May 2001 04:07:16 -0400 (EDT)
• Organization: Universitaet Leipzig
• References: <9e2d7k\$69n@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Hi,

you can't !
The solution would be alpha-blending, but Mathematica's
PostScript can't handle semitransparent colors.

Regards
Jens

Xiangdong Liu wrote:
>
> Hello (again)!
>
> I posted a similar message earlier, but it didn't seem to make
> it to the newsgroups.
>
> I wonder if I can draw two overlapping shapes each filled with
> a different color and make the overlapping region to have the
> blending color of those of the two shapes.  In other words,
> can I fill shapes with transparent colors (ink) rather than
> opaque colors (ink)?
>
> For example, I could do
>
> In[1]:= Show[Graphics[{RGBColor[0.5, 0.0, 0.0],
>                        Polygon[{{0,0}, {0,2}, {2,2}, {2,0}}]}]];
>
> In[2]:= Show[Graphics[{RGBColor[0.0, 0.0, 0.5],
>                        Polygon[{{1,1}, {1,3}, {3,3}, {3,1}}]}]];
>
> In[3]:= Show[Out[1], Out[2]];
>
> But the color in the overlapping square area is
> RGBColor[0.0, 0.0, 0.5].
>
> Thank you all!
>
> Xiangdong Liu

```

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