Ratchet & Clank: Size Matters

[deedub]

There's an issue with depth processing of some effects. For example in the factory level (like 3rd or 4th planet) a smoke effect in a location is seen a mile away (as in it doesn't get blocked by all the object before it). Forcing depth in the hacks kinda erases it, but not nearly enough to make it unnoticeable.

I just noticed this too. The easiest place to see it is in the first area, at the waterfall.

I know what causes it, but AFAICT there is currently no setting to fix it.

It specifically happens for effects that are rendered in lower-resolution (a fill-rate optimization for large particles, I think this game uses 1/3rd x 1/3rd size). This effect is implemented like so:
1) Render the scene normally.
2) Copy the scene depth buffer to a lower resolution depth buffer.
3) Render low-resolution particles to a lower resolution color buffer, testing against the low-resolution depth buffer.
4) Add the low-resolution color buffer back to the scene.

It would appear all the steps are working, except for #2 where it copies the scene depth. Without the scene depth, the low-resolution particles show up through geometry, as if with disabled depth test.

Read-from-depth is a relatively common technique, so if it's not working I could see this being a graphical problem with several games.