Re: composite shape

Hi Akira,

If you use shapes with sections (pgon,pcon,arb8,xtru) where all vertices for one section are compressed in one point, the mesh normal vectors used in creating the composite mesh with OpenGL can become messed-up. This is not documented because we did not understand it till now... The shapes are of course valid from tracking point of view (you can see this if raytracing) but their views become wrong. This is due to the point order uncertainty introduced by numerical imprecision (a cross product changing sign). I just attached your macros slightly changed to avoid this problem.

Best,
Andrei

OKUMURA, Akira wrote:
> Hello ROOTers,
>
> The example I attached in my previous mail was little bit complicated. I
> will attache new three examples. Could anyone give me advises, please?
>
> Sincerely
>
> OKUMURA, Akira oxon_at_icrr.u-tokyo.ac.jp
> Institute for Cosmic Ray Research, University of Tokyo
> 5-1-5 Kashiwanoha Kashiwa Chiba 277-8582 Japan
> Phone/Fax : +81 4-7136-3153
> Skype : okumura.akira
>
> On 2007/10/04, at 4:11, OKUMURA, Akira wrote:
>

>> Hello ROOTers,
>>
>> The attached macro, test.C draws a canvas like attached GIF file. 
>> However some expected cut are not done in the view. The red lines show 
>> cut lines I expected.  How can I modify the macro?
>>
>> ROOT 5.17.02 + OS X 10.4 PPC
>>
>> Sincerely
>>
>> OKUMURA, Akira oxon_at_icrr.u-tokyo.ac.jp
>> Institute for Cosmic Ray Research, University of Tokyo
>> 5-1-5 Kashiwanoha Kashiwa Chiba 277-8582 Japan
>> Phone/Fax : +81 4-7136-3153
>> Skype : okumura.akira<test.gif><test.C>