UE4.27: 2 Groups of Crowds Cheering 01

There are quite a few features and limitations in this system that should be mentioned. The first one, character. In order to have a better production environment the same type character should share the same skeleton (i.e., Tall & Skinny and Chubby & Short are two different types, so they should have two skeletons.) and all characters should have LODs. The system is trigger by animation blueprint which means the animations are given by animation blueprint. Therefore, the same type character should use the same animation blueprint to run the animations. In this case, I only have one type of character. So, everybody is sharing the same skeleton and animation blueprint.

I create a spline and get the spline length divide by a given number, then I'll get a distance between each neighbor number.  An easy math, if I want to control the distance between each neighbor then I can receive the number of columns. 

Length / Segments = Distance -> Length / Distance = Segments

Once you get to control distance and segments then it's very easy to make rows and calculate the positions. And rotations are rotation of the distance along spline.

In order to get the positions, we need to set origin for each point. Each point has its own 3d transform pivot point, but they are all associate with the spline. The position is following this method: Nx(Spline), Ny(Spline) stands for the normal vector of a point on the spline; x1, y1 and z1 stands for the real world transform location; RDistance stands for the distance between rows; NRow stands for Number of row; RHeight stands for height between rows.

 X = x1 + Ny(Spline) * RDistance * NRow

Y = y1 + (RDistance * NRow) * Nx(Spline) * (-1)

Z = z1 + (RDistance * NRow) * RHeight

This method can create the rows which has exact same number of columns and has the same vector for each row. However, the real world doesn't arrange seats with the same method. If you have a better idea how to calculate the positions, please let me know!

The optimization is still in progress, this workflow is using skeletal mesh components and blueprint actor to trigger multiple animations running on engine time. It is quite expensive running up to 200 agents on UE4.27 on my PC. For empty scene, it can run around 50 plus FPS with dynamic animations and great blend in montages. At this point, I have not tried to reproduce the project on UE5 yet. Though the idea is creating a seamlessly and random animation clips for crowds. And compared to VAT, skeletal mesh is still better with blending animations and mesh itself has much more detail and dynamic look.