Particle Simulator and Deflectors/Forces

Just1MoreTry Posts: 25 Enthusiast


I'm trying to create an effect where some 3D text pushes through a cloud, pushing the particles out of the way. I'm hoping to get a really obvious push, but my efforts are so far getting me nothing.

I'm starting with the 'fluffy clouds' preset in the particle simulator, and moving some BorisFX 3D text along the Z axis, towards the camera.

I've tried deflectors, forces and both. 3 different cuboid deflectors/forces are mapped to change position in line with the first 3 letters of the 3D text I'm moving through the scene. I've tried it with and without kill particles.

Here's what it looks like right now:

And here's the link to the actual file:!AhIdG-Oz2TI3g6Ufk1j9sZoeTYWXOQ?e=1d148K

Any help on where I'm going wrong would be much appreciated!

  • CPU i5-7600k
  • GPU GTX1070
  • Win 11
  • 16GM RAM


  • Stargazer54
    Stargazer54 Posts: 3,758 Ambassador

    @Just1MoreTry You are on the right track with the deflector idea, but deflectors only affect particles. Your letters will need to be layers parented to a particle. The text layer is simply text. There is nothing there for the deflector to interact with.

    I really like the look you came up with and love the color scheme! That said, sometimes you just have to do animation the old fashioned way - with keyframing. Perhaps you could break up your text so that each letter is it's own layer. Then you can keyframe their movement "as if" they are being deflected by another force.

    Again, the deflectors only impact particles. But you can apply images to the particles or use the built in shapes that come with them. You get to that by selecting Emitter then Shape. You have multiple options there, such as Sphere, Circle and Layer. With using Layer you can attach a Layer to the particles -which could be an image layer or 3D object layer. If you just want it to be one letter you are going to want just one particle, not hundreds.

    Back to the Deflector - note that the Shape of the Deflector can be either a Cuboid or a Layer. If you create a Plane Layer (set it to 3D) then apply that to the Deflector, then you can have particles bounce off the plane. You can arrange multiple planes to represent rough shapes (but set them to not visible so they don't show in the scene).

    Here is a link to some tutorials on how the particle simulator and deflectors work. Scroll down to the bottom and look for stuff about the deflectors.

    Here is a video I did crashing the Jupiter 2. This was made from multiple composite shots. For the final couple of comps I created multiple plane layers to represent the front of the ship which would push the particles out of the way. Then instanced rocks and boulders onto the particle simulator for the planes to push against. I used another particle sim to create the dust, etc.

  • Triem23
    Triem23 Posts: 20,605 Ambassador

    @Stargazer54 gives a good breakdown here, so I just also note don't forget about the FRICTION and BOUNCE parameters. Those have a large effect on how particles interact with deflectors. To get the letters to "push" smoke aside you'll want a bit of an angle to your deflectors so they can slide off to the side, and you'll want 0 friction with a low bounce. Also the MASS parameter. Higher Mass means particles are less affected by forces.

    You might need to chain up some forces - some cubic detraction to push particles aside (one per letter) with some cubic attractors behind the text to pull particles back into the "wake."

    The particle sim is easily the most complicated effect in Hitfilm. It often takes a lot of experimentation to get a complex sim looking correct.

    For inspiration, this shot was done in HF 2 Ultimate by a user named Mark Edwards. Mark used angled deflectors, detraction and attraction as briefly discussed above to get this White Star to move through the gas cloud. You'll see here it is possible to get a convincing "push aside" of particle clouds. It'll just take awhile to dial in your settings.

    While refining your forces I'd recommend disabling the textures for now and adjusting your particles per second. I find when adjusting physic forces, deflectors it's easier to see what's going on with the white dots.

  • Just1MoreTry
    Just1MoreTry Posts: 25 Enthusiast

    Thanks - though I think you may have misunderstood what I'm after. I appreciate that the letters themselves aren't going to push anything, but I'm positioning deflectors that are children of the Fluffy Clouds Particle Simulator, over the letter, and keyframe moving that deflector to remain in position with the letter.

    The letters are being moved manually, and I want deflectors to push the particles, giving the illusion that the letters are doing the pushing.

    The video @Triem23 posted is pretty much exactly what I'm going for, so it's good to know it's possible!

    As for cuboid/layer, I'd simply been working with a thin cuboid with the rough width/height of the letter - is there any reason why a plane would work better? It's sounding like I need two planes though in a 'wedge' shape in front of the letter (or perhaps 4 in a pyramid/cone shape), with a detraction force within the cone to help push the particles and an attractive force cuboid positioned over the letter.

    Also, friction, bounce, mass (though I'm thinking that because the particles don't have much initial momentum, bounce would be near irrelevant as it's always a fraction of what the particle has at the start?).

    I'm also thinking that I may have to start with the normal Particle Simulator and adapt it to be like the fluffy clouds one, rather than starting with the fluffy clouds preset effect.

    Definitely food for thought, I'll go back to experimenting and report back, thanks both!