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PostPosted: Thu Sep 14, 2017 6:53 am 
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Joined: Wed Mar 16, 2016 10:11 am
Posts: 60
I am trying to encapsulate Bullet to my ECS game engine.
After some test, I can simulate 2000 cubes, dropped randomly on a 2D static plane.
Cubes rarely touch each other.

With rendering + my engine cost, in PC, I get :-
  • >80 fps in normal case
  • 50 fps in the worst case (a brief period that all cubes start to touch the ground)

I ran with :-
  • Windows 7, Intel Core i5-4460 CPU@3.20GHz
  • Visual C++, -O2, release mode
  • single thread
  • without continuous detection (i.e. no CCD)

In this test, I don't share shape, i.e. I use 1 btBoxShape per 1 btRigidBody.
According to the profile, Bullets take about 30% of overall execution time.

My conclusion

Without multi-threading, Bullet can support around 5,000 cubes (if I try very hard).

Question

Is it a correct estimation?
How many btRigidBody your favorite engine can support? (if any)
In 2017, is it practical to achieve https://www.youtube.com/watch?v=J9HaT23b-xc (tower 5,000 planks) in real time?

It is so hard to find some reliable Bullet stress test.
I would like to hear the rough number before designing more gameplay / optimizing further.

Please answer if you happen to know something. I am so lonely in this darkness.


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PostPosted: Thu Sep 14, 2017 9:28 pm 
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Joined: Sun Jul 03, 2005 4:06 pm
Posts: 873
Location: Kirkland, WA
Pierre has done excessive testing which you can read about here:
http://www.codercorner.com/blog/?p=748


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PostPosted: Fri Sep 15, 2017 9:22 pm 
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Joined: Tue Sep 30, 2014 6:03 pm
Posts: 363
Location: San Francisco
Interesting. That was back in 2013 and development has continued on both sides. I wonder what the comparisons look like now.

The GDC-2017 talks by Nvidia about PhysX were impressive. I'm sure they're keeping the CPU side competitive but they're working hard to make the simulation run even faster on Nvidia GPU's.


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PostPosted: Sat Sep 16, 2017 1:40 am 
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Joined: Sun Jul 03, 2005 4:06 pm
Posts: 873
Location: Kirkland, WA
Pierre open sourced Peel. You can download it here:
https://github.com/Pierre-Terdiman/PEEL

I have integrated Rubikon into as well and use it constantly to compare performance. So you can run these tests yourself.


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