Blender Change Request

I just found out that Blender cannot start baking fluid scene from a specific frame. I am hoping this would be an relatively simple update to blender (I do not mean easy or cheap).

If I have power outage and at fame 200 of a fluid bake I’d like to be able to reopen the blender scene and continue the bake from frame 200.

This will only work if there are accessible file from the partially bake scene so that Blender would recognize the last baked file.

Being able to recommence a bake scene due to power outage of other problem would be a huge benefit to Blender users.

this is an important feature that needs to be added

The solution to power outages is UPS systems.

While I agree that resumable fluid bakes would be useful, there’s no point in creating a forum thread about it. Can you imagine what this forum would look like, if each one of the 500 currently active people opened a single thread for every feature they would like to have added?

There realistically is no way you can just request features and have them implemented, no matter how useful you can make them appear.

I am a professional and yes I have UPS 15-30 minutes is not a solution
aain this is getting goff topic.

My suggestion is valid and there is not one person who uses Blender who would not agree being able to recommence a fluid bake from the last frame render is a spectacular idea. I am just surprised it was never even considered as a production must have.

I have a fluid sim that will take 5 days to bake if blender fails or my system crashes or have a power outage…there is no way to recover this except to start again and that leads to what if another issue happens.

Again the solution request is important

It may be important to you just like if you ask a 1000 other users you may get 1000 different things which are incredibly important to them.

However just posting a request in some internet forum is not a very good way to get it implemented since 99% of the time the developers are never going to see this.

If you think it is important contact the relevant module owner or get someone to develop it for you

How to contact developers

My suggestion is valid and there is not one person who uses Blender who would not agree being able to recommence a fluid bake from the last frame render is a spectacular idea. I am just surprised it was never even considered as a production must have.

That may be true, but the point is: It doesn’t matter. The guy who wrote the fluid sim as a student is not an active Blender developer.

It might be a decent idea for more than just power outages (like if you needed to close Blender to do something else on your machine for example or if Windows wants to apply updates), but the best way to implement such a system would be to do it in a way that applies to all simulations that make use of baking, not just the fluid-sim.

This can also be combined with a film stop/resume system for the Cycles engine so you can stop renders in their entirety and resume where you left off much like what is possible in Luxrender, I know I could’ve used it a few times before when I had to stop renders because of Windows updates.

You can actually resume a bake.

Just change the time Start forward in time (based upon your FPS). However, Blender will name the new cache files based upon frame #0. So all that you really need is a way to rename a bunch of files to a new numeric prefix. Sounds like an AddOn could do that if there is not some OS system tool for batch renaming already out there.

How do you know it wasn’t considered. There are many reasons why something may not have made it into the official build even if it was considered to be important.

sounds like a good temporary solution.

Batch renamer I’ve used for years:


Does replacement, prefixes, suffixes, renumbering, etc.

it appears that you can set frames for the smoke domain, but particle baking has no such option?

I am not talking about animation sequences Blenders Fluid sim does not follow that same principal as rendering animation sequences…

To me is it a very easy fix since the blender GZ files are saved to disk with each baked frame and as long as you have the same Blender scene it’s make sense that we should be able to stop and start a fluid bake at anytime

Scott, the problem is that the voxel based fluid sim was a one time student project (as Zalamander mentioned) and it was never really finished. It has many limitations and some are not even possible to work around. It still is useful and pretty fast if you keep the limitations in mind. I don’t see that anyone is interested in improving it, but the particle based fluids may be something that might be workable soon (with OpenVDB implemented).

Anyways its just one of those dead ends you might find in Blender as soon as you start to use it professionally on a tight schedules.

Thank you for the feed back, my understanding and correct me if I am wrong: The Blender fluid sim is based on particles but generates a mesh geometry based on each particle position

I believe it’s actually some sort of voxel system that it uses, it doesn’t use a general SPH-based fluid solver like a lot of the commercial solutions (Blender does have an SPH solver, but no one has gotten around to implement mesh generation).

The smoke simulator uses a similar system, you can find out more about the method these sims use through these research papers here (not everything seen on this site is actually implemented in Blender).

this new addon will it restart a fluid sim from the last frame baked?

First of all. Blender fluid sim, is made for simple sims. You want some real sims that needs a lot of bakeing. go with Realflow or houdini.

The initial implementation of the fluid sim was actually someone’s college research project (looking into 3D fluid simulation), thus it might’ve had an appearance that it was designed to work best in the exact scenarios outlined in the papers. Even now, the different sims in Blender cannot yet communicate with each other in a deeply integrated way and thus you might have one in one part of the scene and another in another part. (and since no one has really stepped up to take that challenge yet, Blender will remain in a permanent position behind most of the commercial solutions until such a project is started).