Unified 3D space glitching

Hey Everyone,

I am making an effect in which light rays rotate around an object in 3D space. However, halfway through compositing the object moved in front of the light rays. If I move around in perspective view, it looks like it wraps around from the side, however from the front the object is always in front of the light ray layer. Due to the Particle Simulator not having the ability to have effects, the glows are applied via a Grade layer. So I cannot move the object underneath the particle sim.

Any idea why? It was working before.


  • Also, I have a Light ray effect nested in a composite shot. In that composite, I have the atomic particle effect. However, that the composite in which that composite is nested has the atomic particle effect applied to it somehow from the nested composite.


  • Triem23Triem23 Moderator

    I don't think this is buggy behavior, but I'm not sure how your layers are set up so I can't be certain. For now I'll just discuss how the compositing modes in Hitfilm work with models and particles and a few other order of Operations things. Screenshots of some of your setup will help. 

    Ok, in Hitfilm a particle or model layer in 2D mode is calculated and rendered immediately. At this point it is effectively a "virtual video clip." This clip then passes to the Effects engine on the layer to process.

    A model/particle layer in 3D mode is the same as 2D except the virtual clip can be positioned in 3D space. This is like moving a plane in 3D.

    In 3D Unrolled mode model/particle layers are calculated, but not rendered until Hitfilm reaches a full 2D photo/video/plane/Grade Layer or the top of the Layer Stack - which is why Layer Effects can't be used on a 3D unrolled model/particle layer. 

    A Grade Layer forces a render of everything below itself (becoming a virtual video clip), then passes to Effects. This is why effects on a Grade effect "everything below." It doesn't  really - the Grade Layer really only adds effects to itself! Therefore, yes, a particle/model layer is "affected" by a Grade Layer - which is really adding effects to the virtual clip render of everything below.

    An embedded Composite Shot in 2D/3D mode is also virtual video clip of everything in the Comp.

    Now, we haven't seen your project and don't know how your layers are set up, but Light Rays is a 2D effect that reads a 3D source position from a point. If your light rays effect is on a plane or grade below your 3D object you are placing your 3D object over a flat 2D bg. Layer order, in this case, determines Composite Order. 

    What is your 3D object? If it's something created with 3D Extrusion, well, that's also a 2D effect. It uses 3D point data to draw a perspective picture onto a 2D layer - it's another "virtual video clip." 3D models were discussed above. Not on my PC to check, so I don't remember if Geometry is creating a "true" 3D object or a virtual video clip. 

    If you're comping a 3D model in a 3D particle sim you should look at "Depth Layers" (Pro Only, not available via Express add-on). This doesn't have any tutorials (I did a quick one, but I seem to have deleted it). Basically  in the layer controls for a model/particle layer in 2D mode is a drop down for Depth Layer. You can, for example, select the particles as depth layer for the model and vice-versa. The layers will calculate, use each other for occlusion, then render. And you can apply effects directly to those layers! 

  • Thanks! No, I wasn't using the Light Rays effect, sorry for using that terminology, I was using a particle simulator to make the effect of light streaks, or paths of light, such as these: https://www.inscapedigital.com/creating-light-streaks-hitfilms-particle-simulator/

    Thanks for the help though! I now know why it wasn't working. 

  • Triem23Triem23 Moderator

    Ok, assuming you're in Pro, just depth layer your particles and object. Should work and you should be able to put glow directly on the particles. 👍

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