Large scene models will Stuck and stopped when fog is turned on

The large scene model will Stuck and stopped for about 2 seconds when the fog is turned on for the first time.
How can I turn on and off fog without blocking rendering?

Hi and welcome to the community,

So, should I read you are setting fog only on user input and it’s only the first time that the scene ‘freezes’ for a while, is it? What about a simple work-around, activating and de-activating fog on scene init? Would that do the trick?

This will make the initialization much slower.

Is it, really? Did you check on it? And actually I just recalled I had a similar issue in one of my very first projects. I suppose you are using the simple fog mode. Using this, I kind of recall I have been keeping fog on at all time and simply changing the parameters (to visually enable/disable fog). I also believe there are now better options to create fog. May be you should give it a quick search in the forum…

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Not enough infos for me to make sure the problem, a playground can explains better.
I guess it is the shader recompile that causes the stuck, you can write your own fog shader in postprocess to avoid that.

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Yes, all the materials must be recompiled with the fog shader when you enable it the first time, there’s no way around it.

As @mawa said, an option would be to turn on fog right at start and keep it all the time, and simply change the parameters to visually enable/disable it. The fog shader code is not very involved, it should not hurt the performance.

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Is there any way that I can perform a material compilation after all the shadows, fog, and environment maps have been modified?

Or is there a way to compile it without affecting the normal rendering of my scene?

Just about 2 seconds slower or even less in your case, which is actually negligible time for the large scene model as in your case.

Yes, just set big values for fogStart / fogEnd (like camera.maxZ):