He Guys. I’m currently working on a simulation for a short film in my free time and stumbled across a logic problem.
the director asked me to reverse the simulation, so the coulds /smoke appear out of the bright light.
Currently the whole simulation is driven by a vortex and noise and i get this great tunnel effect. I tried to generate the smoke form a cylinder, so i get the tunnel like look. I worked with bodyforce and a directional force but it just does not work. In this picture i worked with a vortex and Noise, but the smoke starts to clump together and the whole sim looses the funnel look.
as Vlado suggested you could try reversing the whole animation it’s pretty simple. This would keep the funnel shape and give a look that smoke comes out of the light. Also, it could be a huge time saver.
Yeah this is probably the safest bet. Or i’ll waist my weekend trying to get i look i’ve all ready got.
In this case i would have to resimulate first and than change the timing ?
Ah, if you choose to reverse it, you can check the Input rollout - the Cache Index mode allows you to animate which cache goes at which frame on the timeline without simulating again
Oh great, i absolutely need to test that.
But i figured out why my first tries with the vortex failed. I just messed up a decimal point in the vortex settings and this ruined every simulation i run.
Another question for the retiming. Is there a “looks still good” limit on the play speed setting ?
I’ve reset the whole sim and now it’s working, i’ve still don’t have the perfect look but i’m getting there. I’ll post some results here.
The play speed that might start looking weird when retiming from the Input settings really depends on the setup. Since frames are blended and thus blurred, if you set play speed of 0.5, one frame will be sharp and the next will be blurred and so on, so one trick would be to set the play speed to some value that will not show an exact frame soon, like 0.517 for example Also, if you can afford to wait for a simulation, there is the Resimulation retime (Chaos Docs), which unlike the Time Scale of the simulation tries to keep the same shape and behavior of the smoke/fire. With both the General-Purpose and Slow Down methods you could get a good looking sim - they might start to flicker or pulsate if you have fire and smoke mixed up, but in your setup they might work very well. The general-purpose method could slow down a sim to a play speed of about 0.1-0.2 without anything nasty happening to the result, while the slow-down method could usually go as low as 0.3-0.4 if you use multi-pass advection and 1 step per frame - below that it starts losing detail and will blur the whole thing over time. Also note that the time-bend resimulation will be a bit faster per frame than simulating the original thing - if your original sim is 100 frames, a retime of 500 frames will take around 3-4 times longer than the original, and not 5 times.
Yeah this is great thx. This is the method i need, currently i sim around 500 frames just to take the last 50.
So i can take the last 50 frames of the main sim stretch them and amp them up at the same time ?!
I’m not sure. But the higher i set the buffer in 3.03 the more the results differed from the origional pflow simulation. Thats why i jumped back to 3.0
