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  Physics performance challenge to J.Kesselman...  (Read 17574 times)
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Offline erikd

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Maximumisness


« Reply #60 - Posted 2004-04-18 13:44:23 »

Quote
Err - what like that Java for gaming is cross-platform across Win32 only?


That's just simply not true, however unimpressed you are with mac's current JVM.
Doom 3 in java would probably run like a dog on the mac if it is really that slow, I'll give you that. But that's just one game in just one genre. The majority of games you *can* develop using java *and* run on the mac perfectly well, which makes java a very viable option for cross platform games development. Alien Flux being a real life example from the indie side of games development.
Your challenge to jeff won't prove otherwise, whatever the outcome. When you 'win', it will prove the mac version lags behind performance wise, nothing more.

Offline andyl

Senior Newbie




Java games rock!


« Reply #61 - Posted 2004-04-18 14:04:36 »

Quote
If you're trying to disprove/prove Jeff's points, don't you think he should be setting the rules and you should be approving them?

If you disagree with any of the rules that would indicate a lack of communication skills in Jeff's blog but maybe it would save us wasting a whole bunch of time (and money?) ..

Ok, back to sleep now..

Kev


I gave him the opportunity in my letter:

"The rules will be negotiated to ensure a real and fair test scenario for multiplatform games development in Java, ..."

And as I said above I'm not interested unless he is involved. So your point is ...

Do you guys read anything here, or just leap in on the last thing anyone says, completely out of context of the discussion as a whole?
Offline andyl

Senior Newbie




Java games rock!


« Reply #62 - Posted 2004-04-18 14:21:11 »

Quote


That's just simply not true, however unimpressed you are with mac's current JVM.
Doom 3 in java would probably run like a dog on the mac if it is really that slow, I'll give you that. But that's just one game in just one genre. The majority of games you *can* develop using java *and* run on the mac perfectly well, which makes java a very viable option for cross platform games development. Alien Flux being a real life example from the indie side of games development.
Your challenge to jeff won't prove otherwise, whatever the outcome. When you 'win', it will prove the mac version lags behind performance wise, nothing more.


To reiterate myself for the 1000th time, Jeff has made many bold assertions about Java in his discussion with me, and I'm calling his bluff on just one of them - that cross platform Java performance on Mac and Win32 is a shining example to all of the C programmers out there.

Jeff put words into my mouth:

"I respond:

So you are conceeding the desktop argument and only arguing PS2?

Cool. 'cause thats theoretical anyway today.
I'm glad to know you feel Java is the equal of C/C++ in all the environments its currently deployed Smiley Smiley Smiley"

which I never said. You assume I think performance on Win32 is up to C. He has accused me of creating 'straw men' as he calls them, and putting words into his mouth. Well here is a shining example of him doing it to me. Curiously he seems to imply that he thinks 'Java is the equal of C/C++ in all the environments its currently deployed' (to quote him). Isn't the Mac 'an environment' that java is currently deployed in?

It seems you guys are trying to swivel the discussion around from where it started, so try reading the whole blog, discussion and this thread before jumping in. This is not a discussion about the suitability of Java for 2D and simple 3D games. Maybe try reading my open letter to him, it's not very long and says everything there is to say about the subject.
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Offline kevglass

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« Reply #63 - Posted 2004-04-18 14:37:53 »

Quote

Do you guys read anything here, or just leap in on the last thing anyone says, completely out of context of the discussion as a whole?


Do you ever answer anything without trying to be offensive on the way?

Kev

Offline andyl

Senior Newbie




Java games rock!


« Reply #64 - Posted 2004-04-18 14:39:41 »

Actually I'm a bit tired of reiterating myself, so think on this:

1/ Read the blog, discussion, and afterwards my letter.

2/ If you really believe the assertion that I am challenging, then put up $500 and I'll get some rules up to agree between us. The only objections to rules that I will listen to are those that mean the challenge does not fit the statement I made in my open letter.

3/ Otherwise forget this thread. I am NOT interested in a religious debate, nor any of the other debates some of you guys have tried to turn this into.

I look forward to hearing fromt those of you who believe my challenge can be met.

Andy.
Offline andyl

Senior Newbie




Java games rock!


« Reply #65 - Posted 2004-04-18 14:44:25 »

Quote


Do you ever answer anything without trying to be offensive on the way?

Kev

Kev, my last post until I hear from people taking up the challenge.

It's a direct question born of frustration. Either you did or you didn't. If you did, then you obviously didn't understand my point - I have tried to be crystal clear but obviously failed. If you didn't then where is your objectivity?

I guess you are easily offended which was not intended, but think about which of the above it was...
Offline kevglass

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« Reply #66 - Posted 2004-04-18 14:45:59 »

Quote

my last post until I hear from people taking up the challenge.


Glad to hear it, but yet again I doubt it.

Kev

Offline andyl

Senior Newbie




Java games rock!


« Reply #67 - Posted 2004-04-18 14:47:24 »

Quote


Glad to hear it, but yet again I doubt it.

Kev


And thats not overtly offensive ???????????????????
Offline kevglass

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« Reply #68 - Posted 2004-04-18 14:47:54 »

Yep, it sure was. (born of frustration no doubt)

Kev

Offline andyl

Senior Newbie




Java games rock!


« Reply #69 - Posted 2004-04-18 14:52:24 »

Quote
Yep, it sure was. (born of frustration no doubt)

Kev


Kev, do you watch a TV programme when you don't like it? Then I suggest you change channel.
Games published by our own members! Check 'em out!
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Offline erikd

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« Reply #70 - Posted 2004-04-18 14:53:56 »

When you start a discussion here, you are bound to get it.
I'm not interested in your personal vendetta against jeff, so spare me the details and yes, I read the whole blog.

EDIT:
Quote
1/ Read the blog, discussion, and afterwards my letter.

2/ If you really believe the assertion that I am challenging, then put up $500 and I'll get some rules up to agree between us. The only objections to rules that I will listen to are those that mean the challenge does not fit the statement I made in my open letter.

3/ Otherwise forget this thread. I am NOT interested in a religious debate, nor any of the other debates some of you guys have tried to turn this into.


Basically you just want the community to help you challenge jeff about some point he made, but *only* by putting in big piles of cash. And then you just dismiss any broader discussion about the subject by re-iterating your personal frustrations with jeff over and over again, making you even more frustrated.
You seriously expect something useful will come out of this???

Offline Java Cool Dude

Senior Member




Java forever


« Reply #71 - Posted 2004-04-18 15:50:10 »

/me still awaits the physics algorithms Wink
Offline philwebster

Senior Newbie





« Reply #72 - Posted 2004-04-18 16:07:35 »

Quote
When you start a discussion here, you are bound to get it.
I'm not interested in your personal vendetta against jeff, so spare me the details and yes, I read the whole blog.

EDIT:

Basically you just want the community to help you challenge jeff about some point he made, but *only* by putting in big piles of cash. And then you just dismiss any broader discussion about the subject by re-iterating your personal frustrations with jeff over and over again, making you even more frustrated.
You seriously expect something useful will come out of this???

I'll make this easy. Please answer these questions:
1) There exists a claimed by Jeff that Java is as fast as C/C++. True or false?
2) The osnews.com benchmarks' suitablility for measuring Java's game performace is disputed. True or false?
3) The Full Sail FPS is not available for public analysis. True or false?
4) Positive assertions require evidence, since the burden of proof is on the asserter. True or false?
5) Following on from #2 and #3 - neither suitable benchmarks nor sample implementations have been offered by Jeff to support his statements. True or false?


Offline philwebster

Senior Newbie





« Reply #73 - Posted 2004-04-18 16:08:48 »

Quote


Glad to hear it, but yet again I doubt it.

Kev


Don't be so childish.
Offline kevglass

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« Reply #74 - Posted 2004-04-18 16:18:20 »

Quote

Don't be so childish.


Sorry.

Kev

Offline Bombadil

Senior Member





« Reply #75 - Posted 2004-04-18 17:58:10 »

Maybe it would be a good idea to move this thread to the Webblog from which it started, because it floods this forum in a bad way - remember the unhappy "view last 10 postings"!
People here are used to participate in constructive and helpful threads, usually without flame wars and "my dog is faster than yours" silliness. Simply because we don't need them: most of us here are or have been experienced C++ programmers who know well how Java "is" and are interested in how to make their Java games better. This forum serves this task.
Currently this board doesn't know an anti-advocacy sub-forum. In case one should be created, please move this thread to there, and enable a kill-file feature. Thanks.
Offline erikd

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« Reply #76 - Posted 2004-04-18 18:47:43 »

Quote
'll make this easy. Please answer these questions:

FWIW, I would like to see such a benchmark. I just don't like being patronized when questioning the value of it in the broader picture, thank you very much. Just create the benchmark yourself for whatever it's worth and get it over with.

Quote
Maybe it would be a good idea to move this thread to the Webblog from which it started, because it floods this forum in a bad way - remember the unhappy "view last 10 postings"!
People here are used to participate in constructive and helpful threads, usually without flame wars and "my dog is faster than yours" silliness. Simply because we don't need them: most of us here are or have been experienced C++ programmers who know well how Java "is" and are interested in how to make their Java games better. This forum serves this task.
Currently this board doesn't know an anti-advocacy sub-forum. In case one should be created, please move this thread to there, and enable a kill-file feature. Thanks.


Agreed.

Offline oNyx

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pixels! :x


« Reply #77 - Posted 2004-04-18 23:17:36 »

Evidence, evidence, evidence... now that's a nice word! I have to write it all the time. Evidence!

Most mindnumbing thread ever Grin

What exactly should that "test" show? It would be just another micro benchmark - something wich wouldn't be near a game at all. Oh and writing a "game loop" comment next to the main loop doesn't help.

Q3 for example uses ~10% for logic (vm), ~10% for sound and... uhm... well the rest is for spitting polys at the screen.

A micro benchmark wich has about 95% logic and 5% graphics is - for games - absolutly pointless. Really.

弾幕 ☆ @mahonnaiseblog
Offline William Denniss

JGO Coder


Projects: 2


Fire at will


« Reply #78 - Posted 2004-04-19 00:31:10 »

I don't like the fact that anyone who questions Java is instantly called a troll in these forums.  There are a lot of questions about Java which do need answering.  If the answers are unpleasent, we will know what to fix.

Blind faith is not a friend of technological advancement.

The simple fact that no comprehensive proof exists means that people will be raising these questions until there is.  Rather than trying to stifle these questions, why not answer them?

Will.

Offline swpalmer

JGO Coder




Where's the Kaboom?


« Reply #79 - Posted 2004-04-19 03:22:27 »

Wow... interesting thread.

Here's my 2 cents:

I think Jeff tends to overlook things when he is frustrated with an argument - not because he is losing, but because some point was made by the other side that was wrong... Unfortunately this makes his response overly generalized.

I don't think Jeff checked specifically the performance on the Mac VM befiore he made his response.  I think he based his response on what he knows about the Win32 VM.

It is not fair to ignore so many factors of Java in this sort of argument.  The main argument that I think jeff was trying to get across is that Java is for most games plenty fast enough.   He said it was as fast as C/C++, but he did not say it was faster or slower at any particular thing.  As should be evident, there will be some things you can do faster in C and some things you can do faster in Java.  Jeff even mentioned this with regard to an MPEG codec where it is clear that C/C++ and  SIMD hand coded loops will give you a significant boost.

If you want to go through with a contest, then you have to make the rules a bit fairer..  I think C/C++ will win anyway.. since I believe the nature of this contest will play more to C/C++ strengths that it will to Java's.

But, if you say no to JNI then you must also say no to any use of assembler (inline or otherwise) in the C/C++ version..  since it not much different than using JNI.

Of course I think the whole thing is somewhat ridiculous, since if you were doing a game in Java and you really needed a specific bit to take advantage of things like SIMD you would code some small bits in assembler/C with JNI and move on.   The time you saved using Java for the rest of the game will more than make up for any time lost optimizing a small specific bit with hand coded assembler....  I think that is a large part of the point to using Java for anything.  It doesn't mean put blinders on and pretend that everything in Java will be as fast a C/C++.

I have written code which runs faster in Java than what I got out of Visual C/C++ 6.0, with the exact same algorithm.  I know that Java is not inherently slower than C/C++.  But I also know that there are great many things that I can do in C/C++ faster than what I can get out of pure Java.   As Jeff pointed out, random access into arrays is one such thing.

I think it was Shawn K. that did some tests with basic floating point math and found that it was faster to code the math in Java than to try to be clever and use JNI for the math intensive routines.

Anyway I partially agree with Athomas that there is no point trying to convert C/C++ users.  Just make great games in Java and be happy.

Offline dleskov

Senior Member


Medals: 10



« Reply #80 - Posted 2004-04-19 07:01:17 »

Quote
Anyway I partially agree with Athomas that there is no point trying to convert C/C++ users.  Just make great games in Java and be happy.

There is no point for Java users do that, indeed. We are not talking religion or MLM here. But it makes much sense for Java vendors, led by Sun, so it is apparently Jeff's job, and part of my job too.

I would sign under the paragraphs of your post regarding the use of C++ and Java together as appropriate.

Still I think a community-developed Java Game Benchmark Suite would be a good thing, even if it only allows you to compare different Java implementations and/or hardware. Perhaps it could be built as SPEC JVM98, which is a collection of real life programs. Board game, collision detection, map generation, audio/video codec, AI, scripting, you name it.

Offline andyl

Senior Newbie




Java games rock!


« Reply #81 - Posted 2004-04-19 08:06:39 »

Interesting points, and worth explaining what I have found to be some of the problems with Java:

Quote
I don't think Jeff checked specifically the performance on the Mac VM befiore he made his response.  I think he based his response on what he knows about the Win32 VM.

So which 'facts' do I choose to believe, and which do I reject Huh

Quote

It is not fair to ignore so many factors of Java in this sort of argument.  The main argument that I think jeff was trying to get across is that Java is for most games plenty fast enough.   He said it was as fast as C/C++, but he did not say it was faster or slower at any particular thing.  As should be evident, there will be some things you can do faster in C and some things you can do faster in Java.  Jeff even mentioned this with regard to an MPEG codec where it is clear that C/C++ and  SIMD hand coded loops will give you a significant boost.

Even if 'most games' were referring to AAA titles, 9/10 of those make a loss when they go to market. We have to aim higher than that if we want a return on the development costs. Remember this thread came from a blog directed at mainstream games developers, and was never intended to criticise Java for any other type of game or any other purpose.

Intel C++ will vectorise your code using SIMD and prefetching for you- no hand coding required.

Quote

If you want to go through with a contest, then you have to make the rules a bit fairer..  I think C/C++ will win anyway.. since I believe the nature of this contest will play more to C/C++ strengths that it will to Java's.


I'm interested to hear why you think this - is it that you think it will involve lots of unordered array access or something else?

Quote

But, if you say no to JNI then you must also say no to any use of assembler (inline or otherwise) in the C/C++ version..  since it not much different than using JNI.


But I can add a little inlined assembler in a few seconds, to the points that bottleneck my code. In JNI things have to be planned long before you know if you are optimising prematurely (a bad thing), otherwise it requires a huge amount of re-working the code afterwards, at which point you have lost one of the major selling points of Java: speed of development.

Quote

Of course I think the whole thing is somewhat ridiculous, since if you were doing a game in Java and you really needed a specific bit to take advantage of things like SIMD you would code some small bits in assembler/C with JNI and move on.   The time you saved using Java for the rest of the game will more than make up for any time lost optimizing a small specific bit with hand coded assembler....  I think that is a large part of the point to using Java for anything.  It doesn't mean put blinders on and pretend that everything in Java will be as fast a C/C++.


But in my case I have found when you have optimised all of the rest of the Java code, profiling shows the majority of the time is spent in the vector and matrix classes, and you can't optimise just these classes using JNI (as you point out below). The big limitation with JNI is it is not a fine-grained optimisation method, and this is why other vendors have tried and generally failed with things like JDirect (which Sun put a stop to) and CNI.

Quote

I have written code which runs faster in Java than what I got out of Visual C/C++ 6.0, with the exact same algorithm.  I know that Java is not inherently slower than C/C++.  But I also know that there are great many things that I can do in C/C++ faster than what I can get out of pure Java.   As Jeff pointed out, random access into arrays is one such thing.


Visual C++ 7.0 gets a huge speed bump over 6.0 for the same reason Java 1.4.2 got it's floating point code speedup - using scalar SIMD for it's maths. And if you are targeting the Intel platform, Intel's compiler wipes the floor with Visual C++. C++ compiler performance is still improving in leaps and bounds, so Java is chasing a moving target - do you think it is fair to compare the lastest JVM with a 6 year old compiler like Visual C++ 6.0? Most comparisons seem to be made with this or GCC.

Quote

I think it was Shawn K. that did some tests with basic floating point math and found that it was faster to code the math in Java than to try to be clever and use JNI for the math intensive routines.

Anyway I partially agree with Athomas that there is no point trying to convert C/C++ users.  Just make great games in Java and be happy.


Who said I was a C programmer? I'm a little more pragmatic and use at least 4 different languages (Java included), using whatever is best suited to the task.

But for sure be happy with what you are doing, and do it to the very best of your ability regardless of the language you choose to do it in  Smiley
Offline princec

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« Reply #82 - Posted 2004-04-19 09:54:06 »

Hi Andyl,

I'm one of the normally prolific posters on this forum, and generally regarded to be a Java advocate, despite the fact that most things I say are scathingly critical, offensive, or upsetting, and often specially formulated to wind Jeff up.

My only concrete qualification to comment here is that I hold the dubious distinction here of being someone who has, from start to finish, written a complete commercial Java game that runs on the three desktop platforms.

I have this to say about the whole issue (rather than the whole thread which is about 50% noise):

1. Jeff's job is to evangelise Java without any bloody money. If he'd actually been given a sensible Microsoft-sized budget I'm sure he'd give me some of it to help him further evangelise Java Wink Don't yell at Jeff when he doesn't come up with the cash, moan at Chris Melissinos to hassle the Board for more cash!

2. I've been tinkering with Java for many years now and I can say that it's gotten much, much, much faster than it used to be but the state of play - right now, straight face - is that with the 1.5 server VM on Windows you're going to get around 80-100% of the speed of a MSVC++ framerate. With the client VM expect around 50%-100%, typically lower. The Java evangelists like to dispute my lower figures, but they're basically wrong and I don't care what they think. And this solves your whole thread doesn't it! Just forget what Jeff says about raw compute performance and be happy that Java code is going to get within about 80% of the performance of C++.

3. But the next point is the bit that really pisses off C++ developers and it's where no-one ever manages to see eye-to-eye, and why the whole situation looks like children arguing over their dads' relative merits: It simply DOES NOT matter if Java's throughput is 50% of C++ in this physics collision detection test. If I hired you to make a technical decision for me and you based your decision on this benchmark I'd sack you and ask for the money back, too. Why is this? Because in a real game where it actually counts, you a) won't have 30,000 capsules to perform collision detection on, you'll probably have about 50, and they won't be capsule shaped and b) you've got a lot of other stuff to deal with. Your physics collision detection might be around 5% of your total CPU time.

4. And here's a funny thing: floating point performance literally doubled in the latest release of the JDK. Crazy stuff. Annoying too, because I discovered that floating point was too slow in Alien Flux so I wrote the whole damned game in fixed point, only to have the problem evaporate :/

In a roundabout way, what I'm trying to say is, the whole discussion is a waste of bandwidth. We know Java is slower than C++ (only by a factor of 2, tops, in the worst bits, but mostly it's hardly worth bothering over the difference), and we also know it's Jeff's job to evangelise it, not point out its weak areas.

There's no need to go convincing yourself that the Java version is faster or as fast as C++ in physics calculations - it's easily fast enough and it's a very, very small part of a game development project.

Cas Smiley

btw, regarding Mac performance: I don't see any appreciable difference in framerates in Alien Flux on MacOS, ergo, it's about the same speed as the Windows and Linux x86 implementations.

Offline andyl

Senior Newbie




Java games rock!


« Reply #83 - Posted 2004-04-19 10:21:44 »

Cas,

I'd sack you for stating that physics only takes up 5% of the game without ever knowing what the game is and what it is doing  Wink (Sure, yours might take up 5%.)

I'd like to take a look at your game, the last time I checked the site wasn't available. I'll try again now.

EDIT: You need more bandwidth, 11k/sec is painful! Angry

EDIT: Nice graphics and sound - I'd guess you were in your very early 30's?  Grin (No physically based modelling to speak of though - if you're game isn't doing much in the way of physics then why tell me it's only 5%?)

EDIT: Get Jeff to pull the plug on the thread then, I think you've said it all.
Offline princec

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« Reply #84 - Posted 2004-04-19 12:37:09 »

Quote
I'd sack you for stating that physics only takes up 5% of the game without ever knowing what the game is and what it is doing   (Sure, yours might take up 5%.)
Correct answer Tongue But even without the benefit of a profiler I'd say that you're more likely to hit fillrate and memory bandwidth bottlenecks than CPU ones - most games do.

Quote
I'd like to take a look at your game, the last time I checked the site wasn't available. I'll try again now.

EDIT: You need more bandwidth, 11k/sec is painful!
Sorry Sad I seem to get totally shit bandwidth from theplanet for some reason. Normally I get about 30k/sec out of it, but as soon as someone else starts downloading it's half that, etc...  

Quote
EDIT: Nice graphics and sound - I'd guess you were in your very early 30's?
Turned 31 at Easter (however did you guess Tongue), grew up surrounded by Minters and Braybrooks, and plan to write more of the same Smiley Can't get enough of that old school gameplay.

Quote
(No physically based modelling to speak of though - if you're game isn't doing much in the way of physics then why tell me it's only 5%?)
Shot in the dark - but based on some empirical observations of the distribution of PC CPU speeds and graphics cards. If your game's going to run on a 500MHz CPU then the physics had better be pretty lightweight. If it's going to work on a 2GHz CPU then you're chopping off a fairly big chunk of the market. Etc.

Cas Smiley

Offline Jani Laakso

Junior Member




Do it with Java!


« Reply #85 - Posted 2004-04-19 13:56:42 »

In short: "get the job done faster, cheaper or quicker".
1. I'd say C wins this because it has huge amount of resources (free / commercial libraries) on behind it.
2. If you do not need any additional libraries (scenegraph, physics..) then Java definately wins.

Here's the important comment:
IMHO Java is not ready for serious gaming business (except server side). This is because we do not yet have 3d renderer, 3d scenegraph, sound, physics + bunch of other tools and libraries ready. Some alternatives are coming up, but nothing is production quality (yet). This is the problem, not Java's slowness (it's fast enough). Still, the proof of concept is missing.

Let's see after a year or so if Java then has any excellent gaming libraries available. If this is the case, I see no reason why Java gaming industry wouldn't get started. Currently there's problems with even the 3d renderer libraries (lwjgl, jogl).

Speed: assembler < C < Java, what's the point?

I do not see much point making this kind of contest or debate. It's the whole package that counts, hence you can't never justify any software project with only raw execution speed.

The language itself is good but this is not sufficient alone. Community and Sun's participation is important, jogl is a good start. Community is the "ice breaker" which acts as an critical mass.

The Java language itself simply outperforms assembler or C++. Sure it's somewhat slower but who thinks that this is an real issue? The benefits on all other areas (except raw speed) are huge. C's time is slowly running up while Java  (and other higher level languages) are coming.

Take best parts of any technology at any given time. Don't ever be an idealist (or evangelist) when making technological decisions for commercial products, too bad objectivity can't be bought Smiley

There it was, my ten bucks..

Offline andyl

Senior Newbie




Java games rock!


« Reply #86 - Posted 2004-04-19 14:18:59 »

Holy %$£*& Cas, is that memory footprint in Alien Flux really 88 meg?  Shocked
Offline princec

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« Reply #87 - Posted 2004-04-19 14:28:11 »

Runs fine in 48 or so (look at the actual physical mem usage). Most of it is graphics and sounds. I was deliberate un-clever in handling memory and let the O/S swapfile take care of it - which it does very nicely.

Cas Smiley

Offline NVaidya

Junior Member




Java games rock!


« Reply #88 - Posted 2004-04-19 18:25:07 »

Since things seem to be all quiet on the western front, thought I could troll around a little here.

Firstly, is the challenge that Java should come within *0.5%* of the C/C++ version ? Really ? Seriously ? Why ? The challenge could have been made much more melodramatic if the number thrown at was something like 10% - 20%  Smiley.

While you guys are bandying about how best to generate and visualize physics ( a much abused term if I may say so ) people in other domains are doing some fancy things with Java to test Java's number crunching ability to the fullest. Check out this link from my app.:
http://www.freewebs.com/matspring/ptrackone.htm
Will have to warn you that those pics are a little too big.

Those pics show particle tracking and animation with a 100% Java + Java3D application. Typically simulations such as those entail several hundred thousand polymorphic calls to track particles in a cell-by-cell fashion thru' as big as a million cell grid (polymorphic because the cells could be arbitrary combination of hexas, prisms, pyramids, tets etc.), as many number of Runge-Kutta4 integrations, and several times more Newton-Raphson iterations and all of them in double precision.  My experience has been that the server VM on Windows generally crunches stuff twice as fast the client  because of SSE2 boosts, and overall the speed of Java is comparable to a C++ code (may not be exactly  be apples-to-apples comparisons but I can tell you that I'm not exactly sitting down and wailing on why the heck that I even ventured to code my application in Java - well, atleast not as of yet Smiley ).

And here's something to follow on prince's comment about 5% time for physics. My feeling is that he probably has a valid point. Off the top of my head I've seen that I could do atleast 200 thousand (conservative probably and don't hold me to those numbers) particle track iterations in about 5 seconds. The question is would you really need this many number of calculations in a typical game, and even if Java is 50% slower than C++ how much of that will have an impact on the overall speed of the game. If you really need some hard numbers I'd be happy to produce them, but at a time of my own choice Smiley.

Just my thoughts. And I really do not care to get myself engaged in long drawn debates simply because I need to get a project out pretty soon.

Good luck with your  tryst with the Java-C++ show down. Hope something useful comes out of it once and for all. But one thing for sure. If Java turns out to be 20% slower, and if that turns out to be the reason why people may want to ditch Java, I wouldn't call that exactly  a "wise" decision.

Gravity Sucks !
Offline Raghar

Junior Member




Ue ni taete 'ru hitomi ni kono mi wa dou utsuru


« Reply #89 - Posted 2004-04-19 20:51:29 »

Nothing light the day as much as a nice flame war.

andyl

You reminds me of a uni student that is 2 month - 2 years out of school. A lot of absolute terms, a lot of talking about expensive tools and speed. I didn't notice such demands from other game developers.
You didn't answer me, what do you mean by physic  engine? -_-
Do you actually mean a World engine?

Quote
But I can add a little inlined assembler in a few seconds, to the points that bottleneck my code.

Do you know the macro assembler? It's more safe than inlining and more efficient. It forces you split your code to different parts, not just add inlining to some points. Have you looked at your code after few years? Still readable?
Quote
Intel C++ will vectorise your code using SIMD and prefetching for you- no hand coding required.

Yes it will do it somehow, so you should stop worry and...
How it would work on an AMD? (or 64 bit, or 128 bit)


Best idea would be, if you need graphic engine equal to Havok2, write it down. It might benefit you and the community well. Or perhaps some nice collision library would be better. (Moving points in 3D space are already done.)

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