   The Problem with MatrixTransform
  I use COIN3D to do something. But recently I got a problem.I expect to show a rectangle's two sides. I set white color to the rectangleand made it two show the two sides, now I got a two sides white rectangle. But when I set a Matrixtransform. Actually I set that in an ivFile:Separator{Matrix {1 0 0 0 0 -1 0 0 0 0 1 0 12 3 5 1} File {"rect.iv"}}The result is both of the two sides became black.Now I want to ask that whether there is a similar problem in OpenGL, and is there any simple way to solve the problem?   