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Maniphest T72192

Mantaflow does not render flame when flow source is hidden from Renders
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Description

System Information
Operating system: Windows-7-6.1.7601-SP1 64 Bits
Graphics card: GeForce GTX 1060 6GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 388.13

Blender Version
Broken: version: 2.82 (sub 1), branch: fluid-mantaflow, commit date: 2019-11-26 22:21, hash: rB0ca44974c97f
Worked: (optional)

Short description of error
Mantaflow does not render the flame but only smokes of "fire + smoke" if the flow source is hidden from renders. I hide the source because it is just an emitter not intended to be visible in the final render.

Exact steps for others to reproduce the error

  1. Select the cube in the default new project, create "quick smoke" then change the source flow type to "fire + smoke".
  2. Select the domain object, bake data.
  3. Increase Blackbody Intensity value of the Smoke Domain Material, like 10.
  4. Render the effect, everything is as intended.
  1. Select the flow source, uncheck "Show in Renders" in Objects properties - Visibility.
  2. Free the domain data and bake again.
  3. Render again, now the flame disappear. (Notably the flame is still visible in Rendered Viewport, but not the actual render.)
  1. Enable visibility of the flow source, rebake the domain and everything is back to normal.

Revisions and Commits

rB Blender
rBdf28a68e7009 Fix T72192: Mantaflow does not render flame when flow source is hidden from…

Related Objects

Event Timeline

ifurkend (ifurkend) created this task.Dec 5 2019, 10:43 AM
ifurkend (ifurkend) updated the task description. (Show Details)Dec 5 2019, 10:50 AM
ifurkend (ifurkend) updated the task description. (Show Details)
ifurkend (ifurkend) updated the task description. (Show Details)
Stephen Swaney (stiv) lowered the priority of this task from 90 to 30.Dec 5 2019, 4:24 PM
Stephen Swaney (stiv) added a subscriber: Stephen Swaney (stiv).

If I understand your steps, you uncheck Show in Renders and the object does not show in the render but *does* show in the viewport. This sounds like expected behavior.

If you uncheck Show in Viewports, does it disappear?

ifurkend (ifurkend) added a comment.EditedDec 6 2019, 2:44 AM
In T72192#824583, @Stephen Swaney (stiv) wrote:

If I understand your steps, you uncheck Show in Renders and the object does not show in the render but *does* show in the viewport. This sounds like expected behavior.

If you uncheck Show in Viewports, does it disappear?

The point is only the fire is not shown but the smoke still renders. How can such inconsistency be considered "expected"?
Regarding uncheck Show in Viewports, here's the table for you.

Edit: To clarify that I don't mean changing the visibility of the Domain object,
but the source object where fire/smoke/fluid is emitted from.
Indeed changing the visibility of the Domain is expected to affect the visibility of the fire and smoke,
this is consistent with Blender 2.7.

viewport + renderviewport onlyrender onlyno viewport or render
already baked but change visibility before renderingfinefine in viewport but smoke only in renderfinefine in viewport but smoke only in render
rebakefinefine in viewport but smoke only in rendernothing shownnothing shown

Back in Blender 2.7 to create the similar fire+smoke effect,
hiding the flow source from viewport and render does not prevent either the fire or smoke from being baked and rendered.
This makes the whole situation with Mantaflow so baffling.

Philipp Oeser (lichtwerk) raised the priority of this task from 30 to 90.Dec 17 2019, 12:46 PM
Jacques Lucke (JacquesLucke) changed the task status from Needs Triage to Needs Information from User.Jan 15 2020, 12:51 PM
Jacques Lucke (JacquesLucke) added a subscriber: Jacques Lucke (JacquesLucke).

Is that still an issue in the latest builds from https://builder.blender.org/download/?
If yes, please prepare a very simple .blend file that makes it easier to reproduce the issue.

ifurkend (ifurkend) added a comment.Jan 16 2020, 5:01 AM
In T72192#849459, @Jacques Lucke (JacquesLucke) wrote:

Is that still an issue in the latest builds from https://builder.blender.org/download/?
If yes, please prepare a very simple .blend file that makes it easier to reproduce the issue.

Same issues on fluid-mantaflow-blender-2.82-ed32db06c124-windows64

Mantaflow report 2020 0116.blend585 KBDownload

Jacques Lucke (JacquesLucke) changed the task status from Needs Information from User to Needs Triage.Jan 16 2020, 10:03 AM
Richard Antalik (ISS) changed the task status from Needs Triage to Confirmed.Jan 16 2020, 11:38 PM
Bastien Montagne (mont29) assigned this task to Sebastián Barschkis (sebbas).Jan 20 2020, 11:05 AM
Bastien Montagne (mont29) added a project: Nodes & Physics.
Bastien Montagne (mont29) changed the subtype of this task from "Report" to "Bug".
Richard Antalik (ISS) merged a task: T74841: Volume emission renders in viewport but not in final render.Mar 17 2020, 9:44 PM
Richard Antalik (ISS) added a subscriber: John Cox (theois).
Catalin (cathalyn) added a subscriber: Catalin (cathalyn).May 21 2020, 8:10 PM
Maxim Ponomarov (ponomarovmax) added a subscriber: Maxim Ponomarov (ponomarovmax).May 24 2020, 12:42 AM
Goury (Goury) added a subscriber: Goury (Goury).May 27 2020, 2:07 AM

Are there any plans to ever fix this?
Clearly this isn't how it supposed to (not) work.
It also makes preview useless, slowing down the workflow to stall.

Catalin (cathalyn) added a comment.Jun 2 2020, 8:03 AM

Not sure if it's a proper solution but I found a way to hide the source and maintain the fire in the render.

Select Source -> Material Properties -> Surface -> Select "Transparent BSDF"

Alternatively, you can add an Emission shader in the Volume properties (Select Source -> Material Properties -> VOLUME-> Select "Emission") and set it's color to orange or yellow. This option just reduces the visibility of the source but not in all aspects.

Hope this helps!

Simon Urzua (simonurzua) added a subscriber: Simon Urzua (simonurzua).Jun 6 2020, 11:42 AM

Same issue here in Blender 2.83.0

Galib F. Arrieta (shuffle_master) added a subscriber: Galib F. Arrieta (shuffle_master).Jun 11 2020, 5:31 AM

Same problem here. Blender 2.83. I have a tried everything to get it working. Hiding the flow emitter only renders the smoke, the fire always remain invisible when rendering to an image or as animation.

Galib F. Arrieta (shuffle_master) added a comment.Jun 11 2020, 5:42 AM

Actually, a decent workaround is to add a Principled BSDF material to the flow emitter, and set Alpha to 0. Now I see the fire in the rendered image. This is a similar solution as suggested by @Catalin (cathalyn) .

Georg Bernhard (gogo) added a subscriber: Georg Bernhard (gogo).Jun 14 2020, 10:30 PM

I just ran into the same problem (after a quite time-consuming bake) and the workaround (making the inflow object visible) worked. I wish it wouldn't be necessary though. I unchecked visibilities (camera, diffuse, ...)

Shamimur Rahman (shamimurrahman19) added a subscriber: Shamimur Rahman (shamimurrahman19).Jul 29 2020, 7:00 PM

The problem still exists in 2.83.3

Sebastián Barschkis (sebbas) closed this task as Resolved by committing rBdf28a68e7009: Fix T72192: Mantaflow does not render flame when flow source is hidden from….Aug 4 2020, 6:09 PM
Sebastián Barschkis (sebbas) added a commit: rBdf28a68e7009: Fix T72192: Mantaflow does not render flame when flow source is hidden from….
Aaditya das (imaadityadas) added a subscriber: Aaditya das (imaadityadas).Sep 8 2020, 10:57 PM

I got the same problem and found out that if you disable the flow object from the view port and the render the flames are not visible
so if you re-enable to show the flow object the flames appears in the renders