A question for SIGGRAPH-level graphics nerds

I’ve been wondering if the method the Forza games use for reflections in hood view has a name.

It is basically a version of screen space reflections, but it doesn’t use ray marching. Instead it simply uses a copy of the back buffer (made before the player car and HUD are drawn) as a texture.

So, is it UV mapped SSR? Pseudo-planar reflections? Something else?

You weren’t kidding.

2 Likes

Yep ok sure ???

You may have more luck with this query in suppot section or emailing forza direct

You’re amazed by hood reflections? Um…okay. Real time reflections have been around awhile. Why are you so intrigued by Forza’s reflections out of the TONS of games that have reflections?

Two reasons: Frstly, this method was something I considered back in the '90s as a way to fake real-time reflections in driving games. Secondly, this is a special case where a simple trick like this actually works fairly well. So not having a technical name for it is a bit frustrating…

More complicated tricks like cube maps, SSR, and planar reflections also have limitations that some games reveal quite brutally, making them more an eyesore than an improvement. Then there are games that use those same tricks carefully within their limitations and get away with it. I’m impatiently waiting for proper ray-traced reflections to become viable in real-time.

Well the Xbox One X introduces cube mapped reflections, which by inference indicates the plain Xbox One does not.

Might be real-time cube maps for more objects. Forza Horizon 3 uses a real-time updated (30 fps) cube map for the player car and other nearby cars; local cube maps (updated every few seconds and cross faded) for reflections in the world (such as windows), reflections on cars distant from the player car, as well as reflections on interior detail in cockpit view. It also has a low frame rate cube map (10 fps?) for special cases like chrome detail on the hood.

On the Xbox One X, it might be possible to give each car in a race its own cube map, and if done cleverly even fake reflections of cars onto each other. This can’t be done when they’re sharing a cube map.

Unfortunately, the modest information from Turn10 has made many sites quote them as if dynamic cube mapping hasn’t been done at all before. It is there, alive and well in previous Forzas and other games. But the Xbox One X has apparently allowed them to improve on how they’re used.