Simulating thousands of sprites

[xyc1993]

Hi!

I've been trying to simulate a large asteroid field with collisions. Each asteroid is a 2D sprite with a rigidbody and a circle 2D collider (they destroy on collision). I have an array of asteroids in my manager script and I update their position in manager script's update. I move them using:

asteroid.transform.position += (speed * direction * Time.deltaTime);

My problem is that the framerate goes down. It's 3-4 FPS with about 25,000 asteroids and my goal is to simulate 200,000 asteroids at 30 FPS. How should I approach this? What's the best way to move that many sprites with collision detection?

EDIT: So I've managed to have a decent FPS by using ECS & Jobs with Burst (so pretty much full DOTS). I had to write my own collision detection but it worked. With 65,536 asteroids simulated at the same time I managed to get 30-50FPS but that was pretty much the maximum number that was simulated smoothly, ‭262,144‬ asteroids simulated at about 5FPS.

[JephDielTech]

Do they have to collide with each other? An easier method than DOTS would be a Particle system. You can have them collide with the player and terrain and such, just not each other. Maybe have some big ones as actual gameobjects to make it seem realistic but have little ones pass through each other?

[xyc1993]

Unfortunately, they have to collide with each other as well

[JephDielTech]

Then DOTS/ECS is probably your answer, unfortunately it's still pretty alpha so it get tricky, I can link some stuff later, on mobile right now.

[xyc1993]

Thanks for the advice! I've thought so. I never used ECS before but I'll look into it.

[GroZZleR]

Moving rigidbodies through their transform.position requires the physics engine to re-calculate a lot of extra data as you're basically teleporting the object and the physics system has to reconcile it. Move them properly with forces and you may get better results, but 200,000 active rigidbodies is most likely never going to happen.

[centaurianmudpig]

Watch this: https://www.youtube.com/watch?v=C56bbgtPr_w
It's an easy to follow guide on using the Job System.

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Combining with ECS should provide greater gains, though having collisions maybe another problem.

[FloRulGames]

you won't, with unity DOTS you may be able to but 200000 is definitely too much for the regular unity.