Liquid Emission unlimited #79871

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opened 2020-08-18 10:02:50 +02:00 by Alexey · 13 comments

"Surface Emission" value ignored I suppose, see the screenshot and the project file below:
Screenshot 2020-08-18 at 14.55.53.png
test_emission.blend

That's looks the same or almost same for "Surface Emission"=1,10,100,...

Blender Version 2.90.0 (2.90.0 2020-08-07) on MacOS Mojave.

"Surface Emission" value ignored I suppose, see the screenshot and the project file below: ![Screenshot 2020-08-18 at 14.55.53.png](https://archive.blender.org/developer/F8790394/Screenshot_2020-08-18_at_14.55.53.png) [test_emission.blend](https://archive.blender.org/developer/F8790396/test_emission.blend) That's looks the same or almost same for "Surface Emission"=1,10,100,... Blender Version 2.90.0 (2.90.0 2020-08-07) on MacOS Mojave.
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Added subscriber: @MBG

Added subscriber: @MBG
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Added subscribers: @sebbas, @JacquesLucke

Added subscribers: @sebbas, @JacquesLucke
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Changed status from 'Needs Triage' to: 'Confirmed'

Changed status from 'Needs Triage' to: 'Confirmed'
Member

It does not seem to be completely ignored. I do get small differences. However, it's still a bit weird imo. Looking at the code, there seems to be special behavior when the Surface Emission value is set to zero. Also the relation between the emission value and the surface distance is not quite clear to me. Not sure if there is something wrong in the code, or if just the tooltip has to be improved.

@sebbas, please have a look.

Maybe related commits: cda81d5a4d, 33317b4647

It does not seem to be completely ignored. I do get small differences. However, it's still a bit weird imo. Looking at the code, there seems to be special behavior when the Surface Emission value is set to zero. Also the relation between the emission value and the surface distance is not quite clear to me. Not sure if there is something wrong in the code, or if just the tooltip has to be improved. @sebbas, please have a look. Maybe related commits: cda81d5a4d, 33317b4647

@MBG Can you rephrase the question? I am not sure which part is problematic.
The "surface emission" value is used to emit additional fluid a bit further away from the surface. A value of 0 will therefore not result in no emission.

Also, note that when changing the "surface emission" value, the cache will not be invalidated (this is a known issue with emitter settings in general right now).

@MBG Can you rephrase the question? I am not sure which part is problematic. The "surface emission" value is used to emit additional fluid a bit further away from the surface. A value of 0 will therefore not result in no emission. Also, note that when changing the "surface emission" value, the cache will not be invalidated (this is a known issue with emitter settings in general right now).

Changed status from 'Confirmed' to: 'Resolved'

Changed status from 'Confirmed' to: 'Resolved'
Sebastián Barschkis self-assigned this 2020-10-18 23:15:45 +02:00

Closing for now. I am happy to look into this again with additional information.

Closing for now. I am happy to look into this again with additional information.
Author

@sebbas What additional information do you required? Try to set the surface emission to zero and invalidate cache and for zero-volume plane object we can see the emission as on the screenshot above. Why is it possible? Try to increase the surface emission value and invalidate the cache and the emission is the same or almost the same as before. So what is means the surface emission? We can't control an object emission by the surface emission parameter.

@sebbas What additional information do you required? Try to set the surface emission to zero and invalidate cache and for zero-volume plane object we can see the emission as on the screenshot above. Why is it possible? Try to increase the surface emission value and invalidate the cache and the emission is the same or almost the same as before. So what is means the surface emission? We can't control an object emission by the surface emission parameter.

For liquids, the surface emission value was just used to simulate additional thickness. So a value of 0 just does nothing, a positive value adds some area around the flow object that will be used for emission.
However, I can see how this is a bit confusing: A surface emission value of 0 in a smoke domain effectively turns off the emission.

So assume that's why it's confusing? I am happy to adjust this.

For liquids, the surface emission value was just used to simulate *additional* thickness. So a value of 0 just does nothing, a positive value adds some area around the flow object that will be used for emission. However, I can see how this is a bit confusing: A surface emission value of 0 in a *smoke* domain effectively turns off the emission. So assume that's why it's confusing? I am happy to adjust this.
Author

@sebbas Please explain how much is volume of a planar object for you? I sure it must be zero and flow emission from zero volume needs to be zero too. But it works different. Sorry, I absolutely don’t understand how a finite flow emission coefficient multiplied by zero volume can produce non-zero emission. For now, zero volume produces flow emission and that’s nonsense for me. So, the flow emission doesn’t work properly and it’s unpredictable because there is no math to calculate it.

@sebbas Please explain how much is volume of a planar object for you? I sure it must be zero and flow emission from zero volume needs to be zero too. But it works different. Sorry, I absolutely don’t understand how a finite flow emission coefficient multiplied by zero volume can produce non-zero emission. For now, zero volume produces flow emission and that’s nonsense for me. So, the flow emission doesn’t work properly and it’s unpredictable because there is no math to calculate it.

Changed status from 'Resolved' to: 'Confirmed'

Changed status from 'Resolved' to: 'Confirmed'

Planar objects where defined to have some thickness by default. The reason for this was that some users found it confusing if planes don't automatically emit fluid.
However, I can see how this is not ideal for everyone. Will adjust so that the surface emission value for liquids behaves more like it does for smoke flow objects.

Planar objects where defined to have some thickness by default. The reason for this was that some users found it confusing if planes don't automatically emit fluid. However, I can see how this is not ideal for everyone. Will adjust so that the surface emission value for liquids behaves more like it does for smoke flow objects.
Author

@sebbas Great, thanks.

@sebbas Great, thanks.
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