The purpose for adding DirectX support is to help users who are having serious display problems while running under OpenGL.
If you are NOT having problems with OpenGL, then it is recommended that you continue to use OpenGL for your Rhino display.
There are two technologies, OpenGL and DirectX, used to access a computer's graphics card and perform fast 3-D drawing to a viewport (also known as hardware accelerated drawing.)
Rhino 4.0 by default uses OpenGL. This works great on most system, but some driver/graphics card combination will not work or perform poorly with OpenGL.
DirectX is a technology that is similar to OpenGL in that it allows a program to use hardware accelerated graphics.
Rhino will NOT be dropping OpenGL support.
Eventually all of this will be packaged into a single installer, but for now you will need to install 3 components to get the DirectX plug-in to work on your computer:
Windows 2000/XP - The plug-in should work with SR0 of Rhino 4.0
Windows Vista - The plug-in should work with SR0 of Rhino 4.0
Once the plug-in is installed you are going to need to have some display modes that use DirectX.
If you set one of your viewports to the new display modes, you should be viewing geometry using DirectX (for the first release of this plug-in the words DirectX 9 will display in the lower left corner of the viewport.)
DirectX9Options - Options for displaying DirectX viewports. The options are