Navier-Stokes fluid simulation explained with Godot game engine
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Re: Navier-Stokes fluid simulation explained with Godot game engine
#2So once upon a time I stumbled upon simulating fluids in gamedev and I really wanted to learn how it works. Fast forward 2 months and I decided to write down everything I learned to hopefully make it easier for others in the future!
Re: Navier-Stokes fluid simulation explained with Godot game engine
#3This is really cool. I love how much detail you went into explaining the setup and walking through each piece of the simulation. Definitely bookmarking this to play around with later!
Re: Navier-Stokes fluid simulation explained with Godot game engine
#4So once upon a time I stumbled upon simulating fluids in gamedev and I really wanted to learn how it works. Fast forward 2 months and I decided to write down everything I learned to hopefully make it easier for others in the future!
Fluid sims are just so darn fun! Nice writeup, very accessible.
Couple of notes, I think you forgot to apply timestep when adding rocket exhaust velocity, pretty sure it should be
u[idx] += backward.x * flame_velocity_amount * falloff * delta
v[idx] += backward.y * flame_velocity_amount * falloff * delta
Re: Navier-Stokes fluid simulation explained with Godot game engine
#5So once upon a time I stumbled upon simulating fluids in gamedev and I really wanted to learn how it works. Fast forward 2 months and I decided to write down everything I learned to hopefully make it easier for others in the future!
Fluid sims are just so darn fun! Nice writeup, very accessible. Couple of notes, I think you forgot to apply timestep when adding rocket exhaust velocity, pretty sure it should be u[idx] += backward.x * flame_velocity_amount * falloff * delta v[idx] += backward.y * flame_velocity_amount * falloff * delta You need to compensate by scaling up flame_velocity_amount, I used 85, seemed about the same.
Yeah it seems I missed that, adding the rocket at the end was a cherry on the top and I was so exhausted already I'm surprised it even works lol
Re: Navier-Stokes fluid simulation explained with Godot game engine
#6Earlier quoted context omitted.
Fluid sims are just so darn fun! Nice writeup, very accessible. Couple of notes, I think you forgot to apply timestep when adding rocket exhaust velocity, pretty sure it should be u[idx] += backward.x * flame_velocity_amount * falloff * delta v[idx] += backward.y * flame_velocity_amount * falloff * delta You need to compensate by scaling up flame_velocity_amount, I used 85, seemed about the same.
Yeah it seems I missed that, adding the rocket at the end was a cherry on the top and I was so exhausted already I'm surprised it even works lol
It made it very fun to play with though :D
Re: Navier-Stokes fluid simulation explained with Godot game engine
#7Nice writeup. One thing worth adding to the limitations: without vorticity confinement, the Gauss-Seidel projection step quietly dissipates the small-scale curl that makes smoke look like smoke.
The 2001 Fedkiw/Stam/Jensen "Visual Simulation of Smoke" paper added it back as a correction force for exactly this reason. At N=16 it doesn't matter much because the grid itself can't represent fine vortices, but the moment you crank N up the missing confinement becomes visible.
Re: Navier-Stokes fluid simulation explained with Godot game engine
#8So once upon a time I stumbled upon simulating fluids in gamedev and I really wanted to learn how it works. Fast forward 2 months and I decided to write down everything I learned to hopefully make it easier for others in the future!
excellent article, great vulgarisation and human written !
Thank you
Re: Navier-Stokes fluid simulation explained with Godot game engine
#9Oh don't let us pinch zoom. That would be a disaster.
Re: Navier-Stokes fluid simulation explained with Godot game engine
#10For anyone wanting to dive further, Fluid Simulation for Computer Graphics by Robert Bridson is the definitive textbook.