Fire simulation (fluid-gas) only produces 1 or 2 frames. Then it is unchanging for all future frames. The cache folders have only one or two files.
This problem happens in my complex scene and in that scene with everything but the fire test objects deleted. Fire simulation works in a default scene and if I append the test objects from the complex scene into a default scene. So I think it is some setting causing the problem but I haven’t found it.
Here are two blend files. One is fire working in a default scene. One is all deleted except the fire objects from the complex scene. FireSimBlends.zip (307.1 KB)
I checked every setting in the main .blend vs. a default .blend with working fire sim for the things listed below. Where I found anything different I changed the main one to be like the default one. No luck. Default works. Main does not. I’m out of ammo. No guess what to look for or to try now. Anyone have any ideas?
Things Compared
Domain objects fluid physics
Emitter objects fluid physics
Render properties
Output properties
View layer properties
Scene properties
World properties
I’ll try appending everything from the main .blend into a new .blend. That might get it to work but without knowing what causes this I won’t know what to avoid and won’t know of any easier way to fix it.
The only thing I found is in the deleted Blend…you did not have Cache results checked…and it seemed it was hanging on trying to render the frames directly to disk with no cache…If you manually scrub the timeline instead of playing it would have time to catch up … just for this file I scaled up the domain and object ( a bit small ) placed them on the world origin…applied all transforms… set them to 100 frames at 10fps…and scrubbed through…
Thanks RSEhlers. I hoped that it was me doing “stupid user tricks” (user error) since that’s an easy fix. Cache Results not checked so nothing cached and no sim progress – it makes sense. Wonder why I kept missing that?
Note: “House” means FireTest-HouseAllDeleted.blend in the .zip above. “Default” means FireTestDefaultScene.blend. The fire sim works well in Default but does not work in House. House is a copy of my main project blend with everything deleted except the fire test objects.
Note: I opened two instances of Blender to observe these side by side.
Some ALSO TESTED things seem to have fixed it for RSEhlers but I had no effect.
CROSSOVER TEST
Default fire objects appended into House: The default sim played as far as it was cached to disk in Default blend. I repeated this with different length runs in Default. The House sim was unchanged.
House fire objects appended into Default: Both the Default and the appended House sim ran. Both disk cache folders had many files. Followup: I deleted the disk cache files and repeated the run (pressed Play). Both still worked.
Observation: Once the appended House sim has run in Default then it can be played in Default up to the last frame in the disk cache.
Crossover Test Conclusion: The problem is not with the physics->fluid settings of the emitter and domain. Something in the House blend prevents the simulation from running.
This may narrow the places for the error but does not solve the mystery of what is wrong. It gives hope that appending the entire production scene into a factory setting new blend is a viable work around.
ALSO TESTED
Output Properties → Cache Result: This is not checked in Default so it should not be needed in the House. I checked it anyway. No effect.
Origin to Geometry: I saw that the default blend fire objects had origins in the middle while the House ones had origins far from them. Moved those to the middle of the House objects. No effect.
Objects at world origin:
House - moved objects to world origin. No effect - still not work.
Default - moved objects away from world origin. No effect - still works.
Apply All Transforms:
Applied in House and in Default. No effect.
Post Processing:
Default had none. Set House to the same and deleted compositing nodes. No effect.
Addons:
I checked the enabled addons in both blends. They are the same.
This is my last effort to find the problem. None of this helped so I’ll use work arounds.
Type = Replay so I can move the fire.
TEST
I apended the scene from the production blend (fire not work) into a new blend (fire works). Two scenes in one blend. I’m not familiar with using more than one scene so I may be doing something wrong.
Deleted all the objects from the prod scene. I made a fire emitter and domain in the new scene and in the prod scene. Fire works in New not in Prod.
I looked for differences in the Scenes and Worlds (another World came in with the prod scene).
Difference 1
New scene has surface->use nodes active for World with Surface = background. Prod scene does not. I changed Prod to be like New. No effect.
Difference 2
New had a Volume section in World properties. Prod did not. That section appeared in Prod when I added the surface nodes in Difference 1. No effect.
Difference 3
Prod had custom properties on the scene while New did not. X’ed them off. No effect.
