Very Computer

    I am using TGS OpenInventor 3.0, win32 version, and find out a strange
problem as following:

    I register my callback routine via
"addPostCallback(SoMaterial::getClassTypeId(),_MaterialCB,pAct)". Within the
_MaterialCB,I query the transparency value by
SoCallbackAction::getMaterial():

   ... _MaterialCB(...){
      ...
      float trans;
      pAct->getMaterial(...,trans,0);
      ...
   }

The problem is: When SoCallbackAction traversing a scenegraph with two
cascading SoMaterial nodes,  if the second material's transparency is ZERO,
it does not get a correct ZERO value, instead the previous material's
transparency is returned. If I set the second material's transparency to
0.00001, a very little value, then it does return a 0.00001.   Other fields
of SoMaterial have not such a problem.

-------Sample scenegraph:--------
#Inventor V2.1 ascii

 Separator {

#First material
  Material {
  diffuseColor 0 0.501961 1
  transparency 0.4
  }
  Sphere {
  radius 1.3
  }

#Second material
  Material {
  diffuseColor 0.501961 1 0.501961
  transparency 0  //Problem!
  }
  Cube {
  }

Quote:}

Thanks.

D.J.
2003/4/9