Dave,

That shader is beautifully simple. Seems the reflect HLSL function is doing what I am doing in maths anyway.

Spotted a small problem tho - if you rotate the craft around the y axis, the reflection inverts. Heres one direction:



Heres 180degrees later:



Any idea why this is? maybe its coz I am passing a rotated translation matrix as the WVP?

Heres my effort working properly:



Ta

Simon