I just read about the "reference device' device type in direct3D.
http://msdn.microsoft.com/en-us/library/windows/desktop/bb219625(v=vs.85).aspx
Does this mean I can develop and test (not performance, just visual result) a Direct3D 11 Application including fancy ShaderLevel5 stuff on any old hardware?
Is there an equivalent for OpenGL?
Yes effectively that IS what the reference driver does. Specifically it is there so that hardware rendering can be compared against it. If the hardware rendering does not equal the reference then this can indicate a driver bug (or an "optimisation").
To my knowledge there is no reference driver for OpenGL, unfortunately.
Does this mean I can develop and test (not performance, just visual result) a Direct3D 11 Application including fancy ShaderLevel5 stuff on any old hardware?
Yes. However, you should expect absolutely horrible performance. You could get about 1 frame per minute for complex pixel shaders (directx 9 reference device), and it can take even longer than that. Needless to say, same shader could work in real-time with hardware acceleration. Reference device weren't made for performance, and if I remember correctly, DirectX SDK states (somewhere) that main purpose of reference device was to allow developers to see if their scene looks the way it should and there are no unexpected driver bugs.
Another problem is that if you're running winxp, there will be no DirectX 10 or 11, reference device or not.
Is there an equivalent for OpenGL?
No. Closest thing is mesa3d, but it isn't OpenGL-certified. 1..2 years ago it could display very different picture when GLSL shaders were involved. It could also crash on shaders with flow control. I haven't used it since. however, when used without GLSL shaders, mesa3d was quite fast and comparable to OpenGL, and was significantly faster han reference device in DirectX 9.
