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1  Discussions / Jobs and Resumes / Re: The purpose of this forum on: 2005-02-04 22:50:01
does the polls distribution treats everyone the same?  does the one or two post recruiter get the same weight as long time members?
2  Discussions / Jobs and Resumes / Re: J2EE/.NET Requirements on: 2005-01-27 18:03:02

  • Do you have a good understanding of spam?
  • Do you like to spam message boards?
  • Can you report for spamming in two weeks?

If so, please have fun with the mail address posted above: "" ...
3  Java Game APIs & Engines / J2ME / Re: Cpu speed required on: 2004-11-28 16:25:12

have results on many phones using some java based 2d and 3d benchmarking programs.
4  Game Development / Game Mechanics / Re: Ball Physics in 2D on: 2004-11-26 17:30:05
also forgot, what do you actually mean by static threshold, what could this be set at?

static threshold is when the static friction no longer applies and thus we switch to dynamic.   as i discussed, when you are sliding a heavy box, and all of sudden, it because easy to slide, that is the tipping point upon which you have reached the static friction threshold.  you can google it and find all kinds of numbers for friction constants between surfaces.  but, since you are not really doing a true physics model, the value should just be hand tweaked.  after all, we are "hacking" physics.  try a small value and increment it up until the collision looks realistic.

and, hit a used book store and buy a cheap physics book that has lots of diagrams.   it will help you understand by allowing you to picture in your head of what is going on during these interactions.

best of luck,

5  Game Development / Game Mechanics / Re: Ball Physics in 2D on: 2004-11-26 17:24:06
Cheers for your help, that is really useful.  But there is one more thing I am confused about, how do u know what angle the cue ball and the red ball will travel once they hit?

i'm assuming you have not had a trigonometry class.  that is the type of mathematics that would be helpful here.  

let's look at the simple case.  draw a cue ball.  now, draw two balls touching the cue ball (in front of it).  now draw a line that represents the direction of the cue (it's path).  draw this line to the center point of the que.  now, with the two balls touching the que ball, draw a line from the center of the que ball to the center of the other balls.  that last line should be the direction the second ball is going.

but, how fast will the balls be traveling now?  that will be tough to figure out without trig.   but, we can still cheat without involving trig :>   the clue is in the comparison of the angle made between the line of the cue's path, and the line from the center of the que ball to the center of the ball about to be struck.  between them is an angle.   in your diagram you may have noticed that the larger the angle (or if you have a straight line - 180 degrees) then you will have the maximum transfer of force from the que ball.  if you have a 90' angle, then you have a glancing blow, where the queue will retain most of the energy (speed) and impart a bit on the queue.  so, use your creativity to add some kind of ratio involving this angle into your calculation of how much force is given up by the que ball onto the the collision ball.  

i think you are approaching the limits of what can be done without knowledge of physics and trig.  if this interests you, trig is easy and fun.  you can probably get the physics information you need by skimming here and there without delving too deeply in the mathematics.
6  Game Development / Game Mechanics / Re: Ball Physics in 2D on: 2004-11-25 22:08:48
here is one way to do a math-lite simplified physics simulation:

try subtracting a constant amount from the velocity to add friction to your model.  this will get you a simulated effect for the dynamic component of friction.  for the static component of friction, you basically want to do the same thing, but make it apply only at the initial impact.  this is basically the effect you feel when you have to slide a big box on the floor.  it takes more force at first until the box breaks free, and then it slides much easier.

acceleration isn't worth dealing with if you want to skip math and do simple simulated phyics.

collisions... not sure what a snooker table looks like, but there are basically two types of collision - elastic and inelastic.  elastic collisions keep the energy of the collision in a kinetic form (rather than convert to heat).  for billiard balls, this is what you want.  you have to follow the conservation of momentum.  something like m*v of one particl must be equal to the m*v of the other particle.  since your billiard balls all have equal mass, you are really just passing the speed from one ball to another (assuming no spin).

now, the most difficult aspect of your game would be spin imparted by the cue.  you could always have a spin component that each time step affects the path of the ball, and it may also affect the ball after the collision.   the rate of spin generated will be directly proportional to the force of the cue impact and the distance away from the center of the back of the ball being struck.   so, if you want a little spin, you hit slightly off center, etc, etc.

each time step
   for all balls on table
        if (speed > STATIC_THRESHOLD)
           speed = speed - speed * COEFFICIENT_OF_FRICTION_DYNAMIC + spin
           speed - speed - STATIC_THRESHOLD.

       if speed < 0, speed = 0

i'll leave the implementation of spin up to you, but it should  also take friction into account.  when i hit the ball hard and it spins real fast, that is dynamic friction.  when the ball falls below some threshold speed, it grabs and the static friction sets in.  

i haven't talked about direction at all, but your simple simulated physics can account for everything by just having a speedX and a speedY.  

7  Discussions / Miscellaneous Topics / Re: This is how big China is on: 2004-11-24 03:35:42
I'm amazed that american companies are trying to tell every other country on this planet how to behave and which laws that should apply to them. They really think they run the world.

Hopefully, because of the stupid US copyright laws and software patents, the software industry in India, Russia, China, EU etc. will outgrow the US. Maybe then they'll wake up and smell the coffee.

access to the wealthiest consumers on the planet requires you to abide by u.s. intellectual property laws.  this certainly gives u.s. businesses a head start since they spend a tremendous amount on intellectual property protection.     ms and ibm are patenting stuff like crazy, and i would expect them to eventually use $$$ to lobby patents for eu (remember these guys have billions they could lobby with.)

intellectual property protection is not totally evil or without merit.  it protects an investment, and investment is necessary for development of new technology.  however, the u.s. patent system is broken and should not be used as an international model.

regarding millions of advanced, cheap software engineers around the world...  u.s. companies that manufacture nothing and arbitrage cheap international labor to produce high margin products are probably hoping for such a situation.   a business driven society is a bleak future we are quickly spiraling towards Sad

8  Discussions / Miscellaneous Topics / Re: Death of my Laptop on: 2004-11-24 02:42:15
i'm looking for another laptop as well.  i currently have an ibm x22.  the thing has taken some serious abuse and keeps on ticking.  at work i pound on a painfully slow inspiron 7500 which has had a keyboard and screen replacement (1999 model) but keeps on ticking.

i'm currently looking at the samsung m40 and x30, which are the lightest and thinnest notebooks i know of ( even lighter than powerbooks )  i'm also looking at the ibm t41p which can also passthrough to dvi.  the new inspiron 9200 also looks nice and is cheap, but it is a tad heavy and not available until mid december.

i'd love for some of the powerbook owners to chime in about what aspects or features of the osX/powerbook choice beats x86/linux/xp.  
9  Discussions / Miscellaneous Topics / Re: Death of my Laptop on: 2004-11-24 02:18:37
I'm very used to having to reinstall Windows at LEAST twice a year because my computers always get really slow over time.

start regedit

go here and delete all the crap...

10  Game Development / Shared Code / Re: Singleton with generics - howto? on: 2004-10-21 23:25:19
another possibility is to not use inheritence/generics to abstract.  the gang of four's book "design pattern" usually recommends this method of abstraction.  for example, you could have a singleton that can be used to register other instances as singletons.  if you decide to register your singleton's by type, then you are using the concepts of a "flattened" version of  sun's beancontext.  if you register by string name then you have built a nameservice.
11  Game Development / Networking & Multiplayer / Re: What about ObjectStreams... on: 2004-10-21 23:06:51
the serialized objects are sent over the wire, so there is some extra overhead.   you can actually write your object stream to file and look at it to get a feel for the size of your protocol dialogues are.  if you are working on a lan, it probably isn't a big deal.  one problem you may run into however is that you "wire" objects must synchronized between client and server.  if you are dynamically updating clients then you can see that this becomes a minor annoyance.
12  Game Development / Networking & Multiplayer / Re: How to start a network support... on: 2004-10-18 00:29:57
just think of your clients as having two functions:  1. render the current state  (2) capture user input.   your game server will hold the state of the game, receive client updates, and send view updates to the clients.  this will work well on a lan.  games over the internet are much trickier because of latency issues.
13  Game Development / Newbie & Debugging Questions / Re: How does it work or am I just doff?? on: 2004-10-18 00:23:19
... or am I just a muppet??

G.W. Bush is that you?

political jokes aside...   if you are sure you have a java enabled phone and you want to start researching what that means both in terms of tools and applications, then "google" the term "midlet" (for applications), and  "j2me" (for development.)  also try searching for "message board"   and the model number of your phone.  good luck.
14  Game Development / Artificial Intelligence / Re: [AI] Java Rules engines - especially Rete-base on: 2004-10-15 00:26:50
blah, thought not java-based (in 'c'), you may find some optimization hints in soar's rete implementation.  (  the ICCM'04  soar tutorial given by john laird was very impressive.  soar is an agent cognitive architecture that is production rule based with working memory and lots of other features.  
15  Game Development / Performance Tuning / Re: 3D Interface Based System on: 2004-10-14 15:32:42
your conclusion may be valid, but i don't think you will get a high degree of accuracy timing something that probably takes less time to execute than the accuracy of the timer.  

instead of:

for number of iterations:

for number of iterations

16  Game Development / Game Play & Game Design / Re: Linked Lists and memory management. on: 2004-10-12 23:08:37
in removeStartNode...
if(node != null)

>>headNode.setNextNode(null)<<  this is missing
headNode = node;

same type of mistake in removeEndNode.  you should probably add a method to class node that performs this action.

   next = null
   prev = null

17  Discussions / Miscellaneous Topics / Re: Considering to buy a laptop? Avoid IBM! on: 2004-10-07 18:59:53
i've found the best place to get notebook parts is on ebay, especially for dell notebooks.  search for for "parts" or "broken" + your model number.  i've rebuilt a number of notebooks all from ebay parts.
18  Discussions / Miscellaneous Topics / Re: Considering to buy a laptop? Avoid IBM! on: 2004-10-07 16:50:33
i have yet to see a notebook maker that has a flawless record.

my x22 laptop is going on three years strong without a hitch.  i wouldn't hesitate to buy a new t42p (one of the few laptops that can pass-thru DVI to a monitor.)  but... i have heard that over the years production is slowly moving out of the us and japan and over to china.  ibm also offers 9x5 on-site and next day service on new machines for a few extra bucks.
19  Discussions / Miscellaneous Topics / Re: Simple Peer to Peer Chat Client on: 2004-10-07 16:44:21
check out the juxta project.
20  Game Development / Artificial Intelligence / Re: What do you think of an AI contest? on: 2004-10-07 13:47:47
So I ask, what AI problem will this contest be asking use to compete in solving?

seems to me our choices are:

agent vs agent
agent vs agents
agent team vs agent team
agent vs environment
agents vs environment
agent team vs environment
+ permutations and combinations

if people want agent vs. agent then robocode should be fine.  some of the other choices seem more interesting to me...
21  Game Development / Artificial Intelligence / Re: What do you think of an AI contest? on: 2004-10-06 13:01:00
With my genetic programming hat on, I'd say that they tend to be binary success: you win or you die. You need a game where success is much more analogue, i.e. you will tend to rack up a lot of points before dieing; perhaps use a large arena and seed it with targets that can be shot at for points, or something like that - anything so that most entrants don't just get "you killed 0 enemies, for a score of 0".

good insight.  every adaptive system requires good feedback in order to successfully evolve.
22  Game Development / Artificial Intelligence / Re: What do you think of an AI contest? on: 2004-10-06 12:58:34
a gp approach would be interesting (given that bots are programs in and of themselves), but i have yet to see any research that correlates the complexity of the problem space to the degree of structure necessary within the resultant gp, thus providing some hint about the number of generations and the computational feasibility of the approach.  
23  Game Development / Artificial Intelligence / Re: What do you think of an AI contest? on: 2004-10-05 11:28:59
yeah, this discussion is going in every direction...
To state it again: if enough people are motivated i can work and provide a simple framework and the contest would be to write the best agent AIs.
...but i don't feel enough people will take part.

i think you are right.  seems, we are all more excited about writing or proposing such a framework than providing the ai for it!  maybe we should have an ai plug-in framework writing contest?  or maybe we need an ai agent contest that has cash prizes?  on a related frontier, there are some pokerbot writers that are doing pretty well these days.  
24  Game Development / Artificial Intelligence / Re: What do you think of an AI contest? on: 2004-10-05 00:21:44
Is this a contest for developing AI agents or see who can write the best AI framework environment?

it is neither.  it is a solicititation for interest in an ai contest.
25  Game Development / Artificial Intelligence / Re: What do you think of an AI contest? on: 2004-10-03 22:50:39
sounds like fun, but robot wars has been around since the days of the appleII.  maybe we should shoot for something that looks at other ai application dynamics.

how about:

- each player gets to control n number of bots

- winner determined by team that destroys the other team's base first.

- optional twist could be adding landscape factors where  bots could get trapped, slowed, or damaged if not careful.

- another optional twist might be to allow the agents to modify the environment (blow up barriers, create barriers kinda thing.)  

- bots should be resource bound.  no bot should be able to fire an infinite amount of rounds, etc...

- scoring system would take into number of bots you had left when you won.  it should also be a time-limited event with a slight penalty for draws to prevent sand-bagging strategies.

- implementation of the framework might best be done by providing a bot battle ground server where your bot proxy is controlled by issuing bot commands.  all queued up bot commands that are received are played out based on timestamp for a given game unit timeslice.  controlling clients are free to send their bots commands as often as they like, but each command type should have an effective window of completion.  additional commands received while performing an uncomplete task for a particular resource system of the bot is ignored.  for example if client A sends 100 fire commands in 5 ms and we deem firing to take 10ms, then the bot will only fire once.   but, you could send a fire command and a move command 1 ms apart and have them execute immediately because they involve two separate resource systems of the bot (locomotion system and weapons system.)

just a few thoughts...

26  Game Development / Networking & Multiplayer / Re: javaspaces on: 2004-10-03 22:02:54

They were, up to Jini 1.2 but after that RMI was just one of a few pluggable transport layers.  JERI is the reworked and rethought replacement for RMI.

wow!  that's about when i finished up my jini project.  how do they handle something like:  invoking a network tranparent object?  rmi's activation functionality?  did they ever add a security model?  
27  Game Development / Networking & Multiplayer / Re: javaspaces on: 2004-09-30 11:43:11

NB I'm not trying to be patronising (I'm sure you know this already), just trying to make clear what I mean by saying you can't just do what would seem sensible.

agreed :>  ...further, until you've created such a beast it is just an academic exercise at best, but fun nontheless.
28  Game Development / Networking & Multiplayer / Re: javaspaces on: 2004-09-29 16:47:05

That's not a trivial question to answer, and the going rate for consultantcy on this is $85/hour...

fair enough blahblahblah, but  intuitively it seams very easy to map the mmpog framework requirements directly onto jini or a jini-like framework.   sounds like fun stuff...
29  Game Development / Networking & Multiplayer / Re: javaspaces on: 2004-09-29 16:29:28
(both are available as separate downloads, aren't they?).

nope... javaspaces are just one service in jini.
30  Game Development / Networking & Multiplayer / Re: javaspaces on: 2004-09-29 16:12:57

anyways... heres what makes me abit confused...

if we make a game with javaspaces the objects are
serialized and stored yes?

then say we have a house class. then the database will
have loads of serialized house instances.

if we update the house class because of a bug ;-) then
what happens to all the old serialized house instances
stored in places all over the network...Huh

depend what you modified in the class and whether you include a constant serial version in your class.

now, replacing this house dynamically without shutting down the jvm is a complete different problem that requires more abstraction, registration, versioning metadata, etc...
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