Min Bounces setting in Cycles

In Blender 2.8, Min Bounces was removed as a setting, leaving the heuristic to decide when to terminate a ray. This seems to introduce issues with more complex scenes that involve glass, liquids or even light guides. One example is this bug report.

What are the reasons for removing the min bounces setting? Is it just a UX design or are there deeper changes? Currently it seems that some more complex scenes get a harsh penalty from removing this setting.

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I feel your pain on this one. I have a related issue with simple overlapping transparency - filed and closed here: https://developer.blender.org/T53886

Transparency is useless in most of our production scenes because of this… would be nice to have a fix

This is something I reported here: https://developer.blender.org/rBcd023b6cecb7b8c74de1d16510ad09668b86001f

It is not high on priority list but brecht wrote here it’s on his todo.

Hearing the news that the Release Candidate for 2.8 is coming soon brought me back here to check if anything had been done on this minimum-bounces issue.

This is so important to my business for 2.8 to render just as well as 2.79 yet this might be the first time for me that Blender fails and I can’t go on. You might say I don’t have to upgrade to 2.8 until its fixed but the renderfarm I use will upgrade to latest version and so I can’t use that anymore. I produce images for high profile clients and am proud to use Blender as 2.79 can handle these complex scenes but I can’t continue if these sacrifices to the renderer are being made. I need a fix for this before release!!!


i hope blender didn’t switched to russian roulete that have no control of %

Would a checkbox to turn off Russian roulette be possible? I think most people will want it either on or off, not set min/max bounces like 3/6.

This has been veto’d by Ton already as it would mean rolling back on the speedups that this 2.8 version of Cycles has received. I’m now hoping for a workaround instead at the very least. Tests today have shown to get the same results as 2.79 in 2.8 requires 4x the rendertime when working with glass shaders. Not worth the small speedups in my view.

I’ve added back control over the minimum number of bounces here: