GPU preview

[magilla]

If I turn off the smoke in the preview, the viewport smokes disappears but it remains in the GPU preview. I need to control the GPU smoke via the smoke opacity in the render settings.

This seems a bit awkward, what do other users think?

[Ivaylo Katev]

the viewport and the gpu preview have totally different purposes. the viewport preview is not assumed to be render-like, it's intended to give us as many info about the cache content as possible. for the experienced users it's very very important to know what they have in the cache, i mean the numerical values of the channels. that's why we have these upper and lower limits, actually they are instruments to measure the channel value in given grid cell. for example if one needs to set a threshold for the adaptive grid at certain value, he has to tweak the lower limit of the channel in the preview panel and the value where the cells considered important appears/disappears in the viewport indicates what is the needed threshold. another example - let say you simulate a river and in certain frame there is an annoying unnatural jet, the usual case of instability. you can report this instability and wait for the fix, but you can also workaround it, finding the area that starts the instability using the velocity preview and setting very high level (1000 or more) and using the "draw just a slice" option. when you find the seed of the instability, you can change the geometry that is causing it, usually very small change is enough. this way you can spare few days waiting for our fix. of course we will be very thankful if you report the bugs even if you can workaround them
on the other hand, the gpu preview is intended to represent the content as similar to the final rendering result as possible, and thus it's affected by the render settings, not by the preview settings.