Week 3

Sept 23, 2024 - Sept 29, 2024

I attempted to create meteor shower FX before adjusting the details of asteroid FX so that we can have previz scenes with FX and get a sense of idea how it will look like when all are gathered. Before this week's presentation, we wanted to address that the meteor shower FX was handed over to UE instead of Houdini due to its heavy attributes.

For the meteor shower FX (shooting star cluster effect), I used a fountain Niagara emitter and changed the values of velocity to make the particles fall slightly to the side. Also, I added a location based ribbon emitter for the cluster effect that inherits the location of each particle. To enable getting the location of the particles, I have to check the 'Requires Persistent IDs' in properties.

Meteor Shower FX

Then I changed the details such as lifetime, size, color, spawn rate, etc. I definitely need to modify it to look less stylized as we aim for realistic-looking FX, but for the beauty shot, we still want it to glow a bit.

After the pitch on Tuesday, I got feedback from the professor about the meteor show FX; it looks flat like there is no depth. Therefore, I changed the particle spawn box size to bigger so that the particles can be spawned into a much larger area. Also, I changed the particle size variation so that even without depth, it can be seen that they are far from each other dimension-wise. In addition, I changed the color of the particles so they glow and are more visible.

Asteroid FX - Particle Collision Troubleshooting

For the asteroid FX, I finally changed the meshes into nuts though I only have cashews for now. I wanted to test with actual meshes so I could be precise about how the collision will affect between each particle. There were two videos to prevent particles from colliding with each other and both approaches looked quite similar but I started with the one on the left just because I wanted to learn from scratch instead of utilize pre-made content. Also, editing the existing PBD(Position Based Dynamics) seemed more complicated considering what I had built so far.

While I was following the tutorial, unlike the tutorial example, mine had a failure result which appears in red. I figured out it was because my grid size was too big; it might be also due to the particle spawn shape being a torus which has a hole in the middle, so making a bigger torus generates a bigger hole in the center.

However, as I went further with the tutorials and got more complex, I wasn't able to get the FX look right. The meshes were still colliding with each other, and regardless of the grid size, most of the time the red meshes kept showing. I couldn't make those nuts swirl in a round shape either. I faced so many issues and had a hard time troubleshooting them.

Therefore, I gave a shot to the other tutorial that used PBD rather than being stuck in the same issue.

Though I could make nuts rotate along the torus shape I still couldn't fix the collision.

Below are some assumptions of this issue and the result of the attempt.

1. In a neighbor grid, change the MaxNeighborPerCell and NumCell values to adjust the interaction between particles.

⇀ Even if I changed the MaxNeighborPerCell value larger than the particle spawn number and increased the NumCell value for
subtle division, they still collide with each other.

2. Actual collision of the meshes affects?

⇀ I even added simplified sphere collision to each mesh whose collision size is bigger than the actual mesh, but it still doesn't work.

3. Is the imported mesh size in the Niagara system too small/big compared to the mesh given in the PBD preset?

⇀ I am pretty sure this has nothing to do with collision since the tutorial I saw had no problem with collision with a different mesh.

4. Does Vortex Force cause collision issues while it makes the meshes move?

⇀ Particle meshes still collided even when Vortex Force was turned off.

The asteroid FX takes more time and endeavor than I expected and still have no clue how to fix it, but I will search for more solutions and tutorials. I might need to ask in the Unreal Engine forum at some point if I can't find a good source. Additionally, I predict we will have 40+ meshes for the nuts, I should consider if I would put every mesh in one particle using the array, search if there is any way I can randomize the meshes outside of the Niagara system, or have different Niagara systems per nuts and combine them in the scene.

Last but not least, hope my place can get the power back in the coming week!

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