lvidx30
============

* parsurf.bb.max.z is -4.87mm lower

* thin tube cut by big cone diff intersect


::

    op --dlv30 

    op --dlv30 --gltf 3

        looks fine raytrace matching g4poly 
        ... this geometry causes poor parsurf bb precision



::

    20   4.87451                 OcrGdsTfbInLso0xbfa2370 lvidx  30 nsp    464             intersection difference cylinder cone   nds[  2]  3167 4827 . 
         4.87451                 OcrGdsTfbInLso0xbfa2370 lvidx  30 nsp    464

          amn (    484.123 -1279.737  -150.798) 
          bmn (    484.130 -1279.740  -150.798) 
          dmn (     -0.007     0.003    -0.000) 

          amx (    549.123 -1214.737    82.816)    parsurf.bb.max.z is -4.87mm lower
          bmx (    549.130 -1214.740    87.691) 
          dmx (     -0.007     0.003    -4.875)


::

     78 # generated by tboolean.py : 20170706-1446 
     79 # opticks-;opticks-tbool 30 
     80 # opticks-;opticks-tbool-vi 30 
     81 
     82 
     83 a = CSG("cone", param = [5879.795,-150.798,125.000,150.798],param1 = [0.000,0.000,0.000,0.000])

     84 b = CSG("cylinder", param = [0.000,0.000,0.000,32.500],param1 = [-150.798,150.798,0.000,0.000])
     85 c = CSG("cylinder", param = [0.000,0.000,0.000,31.500],param1 = [-152.306,152.306,0.000,0.000])
     86 bc = CSG("difference", left=b, right=c)
     87 bc.transform = [[1.000,0.000,0.000,0.000],[0.000,1.000,0.000,0.000],[0.000,0.000,1.000,0.000],[516.623,-1247.237,0.000,1.000]]
     88 
     89 abc = CSG("intersection", left=a, right=bc)
     90 

          coincidence at z = 150.798