Unity DOTS Community Challenge #1 Submission

This is my submission for the Unity DOTS Community Challenge #1 Hosted by Turbo Makes Games Information about the challenge can be found here

The challenge was to create a Conway's Game of Life simulation using Unity's Data Oriented Technology Stack (DOTS).

Strategy

I did not have a lot of time to work on this project, so I decided to keep things simple. I created a System for spawning the cells and another that runs the simulation. I used a DynamicBuffer to store the state of the cells and a Quad prefab to render them.

I knew I needed an array for the Grid of cells, to store a bool of whether the cell is alive or dead. I remembered from the recent Unity Dots Bootcamp how they used a DynamicBuffer to store the heatmap and calculated the new state based on a copy as a NativeArray, toNativeArray while changing the underlying of the buffer using asNativearray in a job, so I decided to use the same strategy to run the simulation to calculate the new state of the cells.

For rendering I decided to use a Quad prefab with URPMaterialPropertyBaseColor and set it to black or green depending if the cell was dead or alive.

Since the DynamicBuffer update approach was compatible with IEntityJob using the [EntityIndexInQuery] execute attribute as index for the array, I ended up updating DynamicBuffer and the Cell entities in the same job.

The thing that cost me the most was the actual spawn of the cells. First I used a loop doing EntityManager.Instantiate but that didn't perform well at all... So I decided to use a IJobParallelFor in the SpawnSystem to populate the grid with random bool values (dead/alive) and then instantiate all the Cell entities with the EntityManager in one call state.EntityManager.Instantiate(prefabs.CellColorPrefab, cellsBuffer.Length, Allocator.Temp) a use an IJobEntity with the DynamicBuffer of cellStates to set the Position and the Color of the cells.

The whole thing is triggered from the MonoBehaviour creating/destroying singletonEntities and using the state.RequireForUpdate to drive whether or not a system should run.

I also had the idea to Flip the Quads 180º on X-Axis instead of changing the color of the material, but the performance was a little worse than changing the colors and I dropped the idea.

The final submission contains two implementation of the simulation, a MainThread and IEntityJob approach that you can select before starting it.

Performance

Mac i9 16-Cores

I was able to simulate 1024x1024 (1.048.576) cells at 60fps on my Macbook 16-Core Intel Core i9.

And 2048x2048 (4.194.304) cells at 20fps on my Macbook 16-Core Intel Core i9.

Windows i7 12-Cores

On windows the simulation went a little better considering it has less cores (almost same clock) but I think its because of the Video Card. Up to 70fps on 1024x1024 grid (1.048.576 cells)

But same 20fps on 2048x2048 grid (4.194.304 cells)

DennisFederico/unity.dots.challenge.conways

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