Search found 10 matches

by sAm_vdP
Sat May 05, 2018 1:24 pm
Forum: General
Topic: Deterministic fixed-point port, open source
Replies: 26
Views: 1768

Re: Deterministic fixed-point port, open source

From what I hear from Norbo, there's not much hope of getting V2 to be deterministic. Its highly optimized to use SIMD instructions, which don't really translate to integer math at all.
by sAm_vdP
Fri May 04, 2018 3:30 pm
Forum: General
Topic: Deterministic fixed-point port, open source
Replies: 26
Views: 1768

Re: Deterministic fixed-point port, open source

Hey, thanks for forking!

Where exactly did you notice jitter? Running the BEPUphysics demo scenes I didn't really notice any jitter, so maybe there's a bug I missed?
by sAm_vdP
Wed Feb 28, 2018 12:42 pm
Forum: General
Topic: Deterministic fixed-point port, open source
Replies: 26
Views: 1768

Re: Deterministic fixed-point port, open source

I am of course measuring the results with a benchmark. I am using four of the BEPUphysics demos and running them for 1000 steps each and measuring the full runtime: Old version (inlined without ref): DiscreteVsContinuousBenchmark... 0.21s InverseKinematicsBenchmark... 17.31s PathFollowingBenchmark.....
by sAm_vdP
Wed Feb 28, 2018 7:48 am
Forum: General
Topic: Deterministic fixed-point port, open source
Replies: 26
Views: 1768

Re: Deterministic fixed-point port, open source

Thank you both so much for your help with this, I very much appreciate it! @test44x: I did see your inlining comment, but I think there's more going on: (a.M11.rawVal * b.M11.rawVal) >> Fast64.Q This should more or less turn into a single mul machine instruction and a shift, but aren't you losing ha...
by sAm_vdP
Tue Feb 27, 2018 11:23 am
Forum: General
Topic: Deterministic fixed-point port, open source
Replies: 26
Views: 1768

Re: Deterministic fixed-point port, open source

Thank you for the hints! The disassembly in particular looks interesting, if a bit overwhelming at first. I think one relative low hanging fruit should be the fixed point multiplication: var xl = x.RawValue; var yl = y.RawValue; var xlo = (ulong)(xl & 0x00000000FFFFFFFF); var xhi = xl >> FRACTIONAL_...
by sAm_vdP
Mon Feb 26, 2018 9:16 am
Forum: General
Topic: Deterministic fixed-point port, open source
Replies: 26
Views: 1768

[RELEASED] Deterministic fixed-point port, open source

I have released the current state of the fork: https://github.com/sam-vdp/bepuphysics1int All existing BEPUphysics demos work as expected. However, the performance is still quite bad, about 4 times slower than the float version. I am getting quite different profiler results when using sampling or in...
by sAm_vdP
Mon Feb 26, 2018 9:13 am
Forum: Questions and Help
Topic: Deterministic Lock-step in Unity3D(iOS/Android)
Replies: 17
Views: 5268

Re: Deterministic Lock-step in Unity3D(iOS/Android)

I am currently working on a deterministic fixed-point port of BEPUphysics v1. The current state of the project is available at https://github.com/sam-vdp/bepuphysics1int . All existing BEPUphysics demos work, but the fork is about 4 times slower than the float version. PR, bug reports and performanc...
by sAm_vdP
Thu Feb 15, 2018 11:31 am
Forum: General
Topic: Deterministic fixed-point port, open source
Replies: 26
Views: 1768

Re: Deterministic fixed-point port, open source

EDIT: Problems solved (for now), just posting for general info. As always, thank you for your brilliant help! However, I would be surprised if the jitteriness is actually caused by a lack of precision; I would assume the problem is elsewhere. Spot on. FixedMath uses a pretty rough approximation for...
by sAm_vdP
Tue Feb 13, 2018 7:38 am
Forum: General
Topic: Deterministic fixed-point port, open source
Replies: 26
Views: 1768

Re: Deterministic fixed-point port, open source

Thank you for your help! I managed to get the Pow-function implemented, but now I've hit some more issues. Most of the demos work as expected, if a bit slower, but two behave weirdly: 1. The moving object in the PathFollowingDemo is a bit jittery, I guess that's just a lack of precision converting f...
by sAm_vdP
Sun Feb 11, 2018 12:24 pm
Forum: General
Topic: Deterministic fixed-point port, open source
Replies: 26
Views: 1768

Deterministic fixed-point port, open source

EDIT: Source code is now available at https://github.com/sam-vdp/bepuphysics1int Hi everyone, like test44x I was looking for a deterministic fixed-point physics engine and have started porting BEPUv1 to use integer math. I followed the instructions from the previous thread quite closely and the port...