Bloom in Path of Exile

We introduced a new system for graphical Bloom in Path of Exile: Harvest. As there has been some community feedback on this system recently, we wanted to explain the changes and what options there are for it in the future.

In preparation for Path of Exile 2, we have been revamping Path of Exile's engine to both perform better and to switch towards Physically-based Rendering techniques. Bloom is an example of a graphical technique that can make a scene look more realistic if applied correctly. Bloom simulates the diffraction of every light ray on the aperture of the game's virtual eye/camera. When done well, it makes games look a lot more realistic and helps avoid the uncanny valley of computer graphics while helping us improve performance and development speed.

Bloom is used for far more than just making very bright objects glow - in fact that's generally a bit annoying and we try to minimise that where we can. It's an important part of everything from making metals look shiny to having fires that look and act like actual fire. Every single asset in the game is designed around and relies on the Bloom system.

Historically, Path of Exile used a relatively poor Bloom technique that did not perform particularly well and required us to add specific "Fake Bloom Particles" to effects to make them look how the artists intended. These additional particles had an impact on performance and slowed down our development process. It was possible to disable Bloom by turning off the post-processing layer, but this didn't disable the Fake Bloom Particles which had a noticeable performance cost and were doing most of the work at making it look like Bloom was occurring.

With the release of Harvest, we upgraded to a new Bloom system that looks a lot better while having the same base performance cost as the old system. Because this system handles Bloom properly, the "Fake Bloom Particles" are no longer needed and have been painstakingly removed from as many effects as we could find throughout the game. This was a long process, but improved performance because effects don't need to have so many particles now (as the Bloom part of it is done at a low performance cost by the Bloom shader).

In the past, if we wanted to have something that bloomed a lot (like a glowing armour effect or torch), we'd have to add heaps of Fake Bloom Particles. Now if we want to make something glow, we can just modify a material slightly, and Bloom does all the work. This is a very big performance improvement. In addition, if we were to stack the same effect many times (for example, a player casting a lot of skills fast), then the old system would stack masses of Fake Bloom Particles and the new one would have no additional Bloom cost. It's really a big performance improvement.

It's also a lot faster to make assets and effects this way, which lets stuff be ready earlier in our development cycle, giving us more time to QA it before release.

As we understand that not everyone likes how Bloom looks, we included a "Slight" mode that tones it down to a quarter of its intensity, which was the baseline that we deemed a minimum to still be able to see effects that rely on Bloom.

While the overwhelming majority of players have left the setting on its default value, a few hundred players have expressed significant concern with the Bloom effects and want a way to disable them. This isn't an immediately simple choice to provide, because we have already stripped out all of the Fake Bloom Particles from the effects throughout the game. In order for those effects to be visible, we'd need to reintroduce those particles, which is quite a lot of work.

There's also another element in play. Many of the effects in Path of Exile appear too bright with the new Bloom system. Since the release of Harvest, we have been finding and fixing as many of these as we can, and really appreciate getting reports of specific effects that have problems so that we can fix those. We have set up a new bug reports thread for players to report these issues.

We completely agree that the new Bloom system is an unpleasant experience with the few effects that become way too bright. We have been and will continue to fix these as quickly as possible. We believe that turning a system off rather than fixing it is the wrong solution to the problem.

We want to stress that previously, while it was possible to disable some of the old Bloom via disabling post-processing, all of the Fake Bloom Particles were still there. You couldn't actually disable the Bloom effect completely. Any over-the-top stuff that you're seeing now that you dislike is something we dislike too and want to fix.

So, where to from here? These are the options available to us:

Fix all the problems and rely on Slight being good enough for players who don't like Bloom

This is our preferred solution. There are many cases that need to be fixed and every example players give us (of something they don't like) is a case we agree needs fixing. Ideally once all the cases are fixed, Slight mode will be fine for players who don't like Bloom. At the very least, we feel that this is the best option to try first, before the more destructive other options.

Allow players to disable Bloom by restoring the Fake Bloom Particles

We can't just turn outright Bloom off, or else various effects will not be drawn as the artists intend them to. In order to facilitate disabling it, we'd need to develop a system to conditionally show the Fake Bloom Particles, restore all the ones that we manually removed, and then continue to maintain and test Bloom and non-Bloom versions of all effects in the future. This would be an incredibly large amount of work, and is not at all the right direction for Path of Exile's future.

Potentially modify the "Slight" setting to another value

25% might not be the right spot for this setting. Our artists want to get everything to look correct and not be overbearing, which will ideally allow them to turn the Bloom up slightly so that all effects look better. So the final value we settle on here might be higher or lower than 25%, which we can determine once we have gotten rid of the cases where it's blowing the screen up (taking your feedback into account, of course!)

We understand that for the players who find Bloom uncomfortable, this is probably quite frustrating. We're sorry that there isn't an easier path to resolving it, and that fixing all the cases is taking time. We expected to get most of the bad cases fixed before the release of Harvest, but effects of lockdown made this more difficult than expected.

Please post about any examples of spells and effects that are too bright in the bug reports thread. If the end result of this approach doesn't resolve it to people's satisfaction then we will find another solution.