transparent objects not rendered with vtk9 and mesa 18.3.6 on centos7

I tried to use VTK 9.0.2 to show transparent objects on CentOS-7 with mesa , but the objects which is set opacity less than 1.0 will not render.

I’v tried use LIBGL_ALWAYS_SOFTWARE=1 , it doesn’t work.

Has anyone using mesa experienced similar problems?