Hello,
Can any one help me figure out how to create an optional fuel object for the pyro solver. I can't seem to figure it out. I've watched the pyrofx master class but he doesn't really explain how he built it.
I'm using Houdini Master Version 11.
Thanks
Optional Fuel Object
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- rjkern
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- old_school
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I don't know how it was done in the video or how it was implied but here's one method to add to the fuel in a system.
I used the “Add Field…” shelf option to add a new field called fuel_source then added a Gas Calculate DOP to control how I want the fuel_source added to the fuel in the system.
You have to enable the combustion model in the Pyro Solver to actually get the fuel to burn.
This first method allows you to add dynamic fuel sources, ones that change over time.
A second method is simply pushing in fuel in to the system on the initialization frame directly. Again use SOPs to create a field volume and directly reference that SOP in to the Pyro Object DOP's heat parameter.
It is important to remember that all grid based fluid simulations ultimately take fields as sources, sinks, colliders, fuel and more. Not geometry. So you can rely on the DOP solver tools to convert your geometry to fields in the sim or you do it yourself in SOPs where you can see your sources without having to run the sim.
See the attached example files.
I used the “Add Field…” shelf option to add a new field called fuel_source then added a Gas Calculate DOP to control how I want the fuel_source added to the fuel in the system.
You have to enable the combustion model in the Pyro Solver to actually get the fuel to burn.
This first method allows you to add dynamic fuel sources, ones that change over time.
A second method is simply pushing in fuel in to the system on the initialization frame directly. Again use SOPs to create a field volume and directly reference that SOP in to the Pyro Object DOP's heat parameter.
It is important to remember that all grid based fluid simulations ultimately take fields as sources, sinks, colliders, fuel and more. Not geometry. So you can rely on the DOP solver tools to convert your geometry to fields in the sim or you do it yourself in SOPs where you can see your sources without having to run the sim.
See the attached example files.
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- old_school
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In the file where I use the Gas Calculate DOP, I had the Calculation mode set to Copy. This meant that my custom field was copied in to the heat field which overrode any existing heat.
I changed that to Maximum and brought the heat advection back up to 1. Maximum will merge in the heat field on top of the existing heat field and use the maximum value.
Now you get a heat rising fireball with an added boost when the additional fuel is consumed.
I changed that to Maximum and brought the heat advection back up to 1. Maximum will merge in the heat field on top of the existing heat field and use the maximum value.
Now you get a heat rising fireball with an added boost when the additional fuel is consumed.
There's at least one school like the old school!
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- rjkern
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- old_school
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Easy one and would hope you asked as I forgot to mention it.
In the add_additional_fuel_v002.hip file, in the DOP network, where the SOP Scalar Field DOP is right after the pyro Pyro Object DOP, change the Default Oepration to “Set Always”.
If you want to animate the fuel entering the simulation, you can either cut on or off the Sop Scalar Field DOP adding the field every timestep by animating the Activation parameter from 0 to 1 and back. If you want to animate the amount of fuel you pump in to the simulation easing in and out, you can look at the Gas Calculate DOP in the network. You can keyframe animate the Source Pre-Mult Parameter from 0 to whatevrer and back to 0 to slowly squirt in fuel up to the maximum amount then animate it back down.
Now the fuel is pretty static even though there is a Gas Advect Field DOP set up to move the fuel around by the vel fields. That is because there is nothing moving the velocity field around the fuel until the temperature rises up and ignites the fuel and the temperature field kicks the velocity about.
In the add_additional_fuel_v002.hip file, in the DOP network, where the SOP Scalar Field DOP is right after the pyro Pyro Object DOP, change the Default Oepration to “Set Always”.
If you want to animate the fuel entering the simulation, you can either cut on or off the Sop Scalar Field DOP adding the field every timestep by animating the Activation parameter from 0 to 1 and back. If you want to animate the amount of fuel you pump in to the simulation easing in and out, you can look at the Gas Calculate DOP in the network. You can keyframe animate the Source Pre-Mult Parameter from 0 to whatevrer and back to 0 to slowly squirt in fuel up to the maximum amount then animate it back down.
Now the fuel is pretty static even though there is a Gas Advect Field DOP set up to move the fuel around by the vel fields. That is because there is nothing moving the velocity field around the fuel until the temperature rises up and ignites the fuel and the temperature field kicks the velocity about.
There's at least one school like the old school!
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- rjkern
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hmm… I got that to work just fine in your examples, however when I try to do it in my set up, it still only creates fuel on the first frame. The effect I'm really going for is using one object to set fire to another. My idea for this was to have an object start emitting fuel as it passed through a fire. If you have any better suggestions on how to do this, I would be open to them.
Otherwise I would be very grateful if you could look at my set up and help me figure out what I am doing wrong.
Thanks!
Otherwise I would be very grateful if you could look at my set up and help me figure out what I am doing wrong.
Thanks!
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- mawi
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- old_school
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And here's my worked up file and yes the issue was with the fuel_source SOP Scalar Field DOP. If in doubt, enable “Use SOP Dimensions” which I invariably do as I am lazy and if I can see it in SOPs, well it “should” work. There's no need to match the container adding the additional fuel to that of the actual fluid container. That's overkill imho.
You could have seen that there was no addition of fuel_source to the simulation. If you would have enabled the Scalar Field Visualization DOP set up to control the fuel_source. I enabled it and also enabled view as smoke and nothing was there in your file.
See the other notes in the network in the attached modified file on where to tweak the settings to get a continual burning of a fuel field. It's all in the temperature of the burn. Burn too cold and the fuel fire will extinguish. Too high and you get one of those massive gasoline fireballs. In the middle will get you a continuous burn.
See the example file.
You could have seen that there was no addition of fuel_source to the simulation. If you would have enabled the Scalar Field Visualization DOP set up to control the fuel_source. I enabled it and also enabled view as smoke and nothing was there in your file.
See the other notes in the network in the attached modified file on where to tweak the settings to get a continual burning of a fuel field. It's all in the temperature of the burn. Burn too cold and the fuel fire will extinguish. Too high and you get one of those massive gasoline fireballs. In the middle will get you a continuous burn.
See the example file.
There's at least one school like the old school!
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- rjkern
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