Hello all,

Sorry for my English!

I found a description about the fastest reflection algorithm for flat surfaces. http://www.remi-genin.fr/blog/screen-space-plane-indexed-reflection-in-ghost-recon-wildlands

I want to recreate it in unity. Attached an example for testing https://www.drive.google.com/open?id=1WfgCpxwx8k6lgALHY6s_588p1D4lYEb6

I have some problems.
1) Why does the example use reflection along the Z axis? After all, the example is reflected on the horizontal surface Y?
2) In my implementation, an incorrect hash buffer.
Perhaps the buffer is written in reverse?
I added a z-buffer distance limit for test. You can see what's happen on 40/100/1000 meters.
 

Here is the contents of the hash buffer

I tried to change the interlocked Max / min, reversed the value of the z-buffer, tried without hashing (just write uv), still did not succeed.

3) Another interesting question is filling holes. The author writes this

Temporary reprojection for static images will not work (or am I mistaken?)
And in the second part I did not understand what he was doing? Is it blending the previous frame and the current frame of the reprojection?


ps There are a couple more links for this method, but the code is more complicated and confusing.
http://www.guitarjawa.net/wordpress/wp-content/uploads/2018/04/IMPLEMENTATION-OF-OPTIMIZED-PIXEL-PROJECTEDREFLECTIONS-FOR-PLANAR-REFLECTORS.pdf
http://www.advances.realtimerendering.com/s2017/PixelProjectedReflectionsAC_v_1.92.pdf

Isn't anyone interested the fast ssr reflections?
Maybe someone can recreate the algorithm, even on another engine?

On 6/8/2019 at 10:13 AM, Kripto289 said:

Why does the example use reflection along the Z axis? After all, the example is reflected on the horizontal surface Y?

Some games use Y is up, some games use Z is up.

On 6/8/2019 at 10:13 AM, Kripto289 said:

Here is the contents of the hash buffer

Looks like you're not skipping pixels that are below the plane and shouldn't be reflected?

On 6/8/2019 at 10:13 AM, Kripto289 said:

Temporary reprojection for static images will not work (or am I mistaken?)

Look into temporal anti aliasing (taa). Usually when using this technique, you move the camera by a fraction of a pixel even when static, so there is a small amount of new information. And yeah, for the second part it sounds like if the temporal filter doesn't work, they simply use the last valid reflection color that appeared at this pixel (i.e. draw over the previous reflection texture without clearing it). Camera movement would then "smear" somewhat appropriate colours around in the holes.