I have been working on SSAO for horde3D again since the last week, and I have finally got some great results!
To make this effect, I had to add an another buffer to the render target in the deferred pipeline and this render target contain each pixels position in screen space. The biggest problem Ive got, is that I need to have access to the normal in view space within the SSAO shader and since we don't ahave access to the transformation matrix in this context, I had to replace the GBUffer world space normal by the GBuffer view space normal. At the end it is not a big problem, since the lighting can be done ine view space, but for this demo I don't have any lighting.
You can donwload the demo here : http://www.mediafire.com/download.php?uwmkt2zynhy
BTW, SSAO is a very expensive effect, but some optimisation can be done. The best one is to reduce the buffer size by half. In this demo, the occlusion isn't blurred, so it can look a little bit wrong, but I will try to make a blur shader next week since a simple Gaussian Blur don't do well...
Some screenshots :
With/Without SSAO:
