I would like to create a baseball simulation game.
Are these sports management games based on luck? A management game entirely based on luck is not fair, but it cannot be too predictable either. How does the logic behind these games work?
It's all about probability and statistics. You set the chance of something happening based on some attributes you assign, and then the random factor comes in during play to make things less predictable and more fun. Generally you get a load of statistics from some external source, encode them into your game's database, and write a system that compares random numbers to these statistics to generate results that approximate the real-life observations that the stats were based on.
Oversimplified example: say your game has Babe Ruth who hits a home run 8.5% of the time, and some lesser guy who hits one 4% of the time. These are the attributes you test against. So for each pitch you simulate, pick a random number between 0 and 100%. If it's less than or equal to the attribute, the batter scores a home run, if it's greater than the attribute, they don't. After a few pitches you'll start to see Babe Ruth's quality show relative to the other guy as he will tend to hit over twice as many home runs.
In reality you'd have more than 1 attribute for this, depending on the kind of pitching for example. And the other player might get to choose which relief pitchers to use to try and exploit weaknesses in the batter's abilities. So the gameplay comes from the interplay between these various attributes, with you trying to maximise the chance that the attribute tests work in your favour.
PS. Apologies for any mistakes regarding baseball: I'm English so can't be expected to understand these things. ;)
As you have already figured out, the core component of such games is the match simulation engine. As Spence said so, you want that simulation to "look right" rather than to "be right".
I worked on a rugby game simulation some time ago and there's an approach that works quite well. Your match is a finite state machine. Each game phase is a state, has an outcome which translates to a phase transition or changes in game state (score, replacements, ...).
Add in a event/listener system to handle things that are not strictly related to the structure of the game you're simulating and you have a good structure (everytime something happens in your simulation, a foul for instance, fire an event; the listeners can be a comment-generation system or an AI responsible for teams' strategies).
You can start with a rough simulation engine that handles things at a team level using an average of your players' stats and then move on to something more detailed that's simulating things at a player level. I think that kind of iterative approach suits a game simulation very well because you want it to look right, and as soon as an element looks right you can stop iterating on it and work on another part of your system.
Random is of course part of the game because as you said so, you don't want games to be too predictable. A very simple thing to do is to have virtual dice rolls against a player and team statistics when they are performing a particular action (throwing the ball for instance).
Edit: I make the assumption that we're talking about management games like Hattrick, where you're managing a roster and simulating game results rather than 2D/3D graphical simulations.
Usually timing plus a randomness to make the game replayable EDIT To clarify I mean in terms of when the pitch comes at you, if it was exact you could learn to play it perfectly, you would need a small randomness around the exact time that you swing to make the game have some chance). AI has a big part in this if you do things like curve balls, add the ability to steal bases etc.
Getting games "right" isn't a factor of design or maths so much as a feel. You will try something, play it, and see if it was fun. If it isn't try different algorithms or gameplay until you get it right.
A simulation is very much about an imagined world in that you create classes that represent all aspects of an imagined world. You need to model the players, specify the game rules, and game dynamics.
http://cplus.about.com/b/2008/05/31/nathans-zombie-simulator-in-c.htm
Look here for agent based model: http://www.montemagno.com/projects.html
One great thing about creating your own game is that you get to decide how the game logic is going to work. If you want the game to have a high degree of luck you can design that in. If you don't want the game to have a high degree of luck then you can design it out.
It's your game, you get to make up the rules.
Are you talking about a baseball game you play or a game simulator? Baseball games can be arcade-like or fantasy sports like or a blend.
I was at Dynamix when Front Page Sports Baseball was made. It was stats-based, meaning that you could play out games and seasons using the stats of the various players. That meant licensing Major League data. It used stats to influence outcomes.
There was a regular mode and a "fast-sim" mode that could breeze through the games faster.
I think Kylotan has the right strategy. Baseball has stats for everything. Simulate a game to the most detailed level you can manage. Combine player stats to determine a percentage chance for every outcome. Use randomness to decide the outcome.
For instance: The chance of a hit is based on Batting Average, Pitcher's ERA, etc. The opposing team's feilding percent determines the chance an out becomes an error.
Every stat you display to the 'manager' when selecting lineups should have some effect on gameplay - otherwise the manager is making decisions based on misleading information.
you ought to check out franchise ball. there is a browsable demo.
http://promo.franchiseball.com
Related
I am a beginner gamedev and trying to figure out how to go about implementing my game's inventory management system. I am developing a third person RPG, with heavy emphasis on inventory and crafting, and so it needs to be done right.
I essentially have a tablet device the player will be able to use to access statistics about themselves and should also be their method of ascertaining crafting recipe. An example scenario is as follows: player obtains three recipe items, Apple, Leaf, and Ash. They want to craft a healing poultice in the field. They remove their backpack, which serves as both inventory and a less powerful crafting station, and the camera moves to focus on the backpack as if it were an inventory screen, allowing the player to arrange their ingredients as necessary and then craft.
My problem is I haven't figured out how to manage the control switch. Ideally the player shouldn't be able to walk around and do normal traversal while crafting. Indeed having WASD usable as menu manipulation controls would be preferable. The game is of the type that realtime usage of inventory is part of the experience, so I dont want a static pause screen. What avenue do I need to pursue in my research for this?
I've looked into Cinemachine and state switching/statemachines but I'm still fairly puzzled by that whole affair. I can switch to a state so far, but only sometimes get out of it. I'm away from my computer at the moment so I don't have an example but this concept has been nagging me for hours.
Let's say I have an open world game that supports multiple players.
The game stores their positioning by X and Y in this world.
Also, whoever is playing the game can see a canvas of 11x11, where his player-self is represented on this screen, always centered.
The game world has 1000x1000 squares to walk using keys.
What I know is that:
I could emit events whenever a player walks,
check this event data at the server-side (to see if it is possible and the speed is correct/anti-cheating measures),
update the game state which contains all players and positioning,
re-emit this state from the server so every client would be able to render properly this new player.
The problem is, should I really update someone who isn't even being seen?
When everyone is walking around, moving items, earning levels, etc - those events are being emitted from the client, and that's okay, but thinking about the server-side, it will re-emit that for each update state, and, maybe that will be overloaded?
Also, sending the whole game state, even if it isn't being rendered, opens so many breaches to cheating that this made me think that there is another option.
I'm a beginner at Networking and Game Development, and that is being hard to get into my mind - so I decided to try and put it into a question. This way, maybe with someone reading what I'm thinking about, I might get some clarification. Perhaps I'm just thinking about it the wrong way.
Q: should I really update someone who isn't even being seen?
There is no need.
The normal way MMORPG games do in the server side is to cyclely process network packages and some other calculations like the connection of players like skill cast or something else.
The central of a server may look like below
void run()
{
while (true)
{
processNetwork();
processSkills();
processMoves();
...
}
}
The loop will run several times a second, like 20 frames a second is enough cause players can not feel the little frame, they think they move/play smoothly but the trueth is not.
For your question, player only need to see some little area, when he moves, the server will braodcast his postion to others in the area and the players in his area in the next frame.
And that is just the simpliest model, actual model will be more complicated and we will detach different functions of the game to different server, sucn as chat server, battle server, auction server and others.
OK,
So we want our robot - roomba (the nice vacuum cleaner) to know it's location in a given room.
That means we have the map of the room and the robot is put somewhere and needs to know in a short time where it is located.
We saw a lot of algorithms - where the most relevant one was MCL (monte carlo algorithm) for localization of robots in space.
We are afraid that it is too big for us and don't know where to start from.
We would like to write the code in MATLAB.
So if anyone have any idea where we can find a code - we would apprecate it a lot.
We are open minded about the algorithm - so if you have a better one or something that might work, that will be great. That goes to the language we are writing it in.
Thanks.
Liron.
Interesting.
I've read a lot about trying to keep track of where the roomba is, but it seems like every system that has used only "internal" feedback from the roomba has ended disastrously. Meaning they try to keep track of the wheel locations etc... The main problem is that you can't take into consideration the wheel slip you get and will drastically change based on surface and other factors.
I would recommend using either a stationary based sensor that the roomba can locate from, on-board diagnostic sensors (such as a camera, wiskers, ultrasonic), or a combination of the two.
STAMP makes a great ultrasonic sensor package called the PING((( that can sense up to 6ft. I've used it up to 15 feet, but it works great in close proximity for mapping.
hope this helps!
I'm not really sure what the correct term is, but how are time-based programs like games and simulations made? I've just realized that I've only wrote programs that wait for input, then do something, and am amazed that I have no idea how I would write something like pong :)
How would something like a flight simulator be coded? It obviously wouldn't run as fast as the computer could run it. I'm guessing everything is executed on some kind of cycle. But how do you handle it when a computation takes longer than the cycle.
Also, what is the correct term for this? Searching "time-based programming" doesn't really give me helpful results.
Games are split into simulation (decide what appears, disappears or moves) and rendering (show it on the screen, play sounds). Simulation is designed to be time-dependent: you can tell the simulator "50ms have elapsed" and it will compute 50ms worth of simulation. A typical game loop will render (which takes an arbitrary amount of time), then run the simulator for the duration since the last time the simulator was run.
If the code runs fast, then the simulator steps will be short (only a few ms) and the game will render the scene more often.
If the code runs slowly, the simulator steps will have longer steps and there will be proportionally fewer renders.
If the simulator runs slower than the simulation itself (it takes 100ms to compute 50ms worth of simulation) then the game cannot run. But this is an exceedingly rare situation, and games sometimes have emergency systems that drop the quality of the simulation to improve performance when this happens.
Note that time-dependent does not necessarily mean millisecond-level precision. Some systems implement simulations using time-based functions (traveled distance equals speed times elapsed time), while others run fixed-duration simulation steps.
I think the correct term is "Real-time application".
For the first question, I'm with spender's answer.
If you know the elapsed time between two frames, you can calculate (with physics, for example) the new position of the elements based on the previous ones.
There are two approaches to this, each with advantages and disadvantages.
You can either go frame based, whereby a timer signals n new frames every second. You calculate movement simply by counting elapsed frames. In the case that computation exceeds the available time, the game slows down.
...or, keeping the frame concept, but this time you keep an absolute measure of time, when the next frame is signalled, you calculate world movement via the amount of elapsed time. This means that stuff happens in real-time, but in the case of severe CPU starvation, gameplay will become choppy.
There's an old saying that "the clock is an actor". Time-based programs are event-driven programs, but the clock is a constant source of events. At least, that's a fairly common and reasonably easy way of doing things. It falls down if you're doing hard realtime or very high performance things.
This is where you can learn the basics:
http://www.gamedev.net/reference/start_here/
Nearly all of the games are programmed in real time architecture and the computer capabilities(and the coding of course :)) determine the frame rate.
Game programming is a really complex job including object modeling, scripting, math calculations, fast and nice rendering algorithms and some other stuff like pixel shaders.
So i would recommend you to check out available engines in the first place.(just google "free game engine")
Basic logic is to create an infinite loop (while(true){}) and the loop should:
Listen for the callbacks - you get the keyb, mouse and system messages here.
Do the physics due to the time passed till the previous frame and user inputs.
Render the new frame (gdi, derictX or openGL)
Have fun
Basically, there are 2 different approaches that allow you to add animation to a game:
Frame-based Animation: easier to understand and implement but has some serious disadvantages. Think about it this way: imagine your game runs at 60FPS and it takes 2 seconds to draw a ball that goes from one side of the screen to the other. In other words, the game needs 120 frames to move the ball along the screen. If you run this game on a slow computer that's only able to render 30FPS, it means that after 2 seconds the ball will be at the middle of the screen. So the problem of this approach is that rendering (drawing the objects) and simulation (updating the positions of the objects) are done by the same function.
Time-based Animation: a sophisticated approach that separates the simulation code from the rendering code. The amount of FPS the computer can render will not influence the amount of movement (animation) that has to be done in 2 seconds.
Steven Lambert wrote a fantastic article about these techniques, as well as 3rd approach that solves a few problems with Time-based Animation.
Some time ago I wrote a C++/Qt application to demonstrate all these approaches and you can find a video of the prototype running here:
Source code is available on Github.
Searching for time-based movement will give you better results.
Basically, you either have a timer loop or an event triggered on a regular clock, depending on your language. If it's a loop, you check the time and only react every 1/60th of a second or so.
Some sites
http://www.cppgameprogramming.com/
Ruby game programming
PyGame
Flight Simulation is one of the more complex examples of real-time simulations. The understanding of fluid dynamics, control systems, and numerical methods can be overwhelming.
As an introduction to the subject of flight simulation, I recommend Build Your Own Flight Sim in C++. It is out of print, but seems to be available used. This book is from 1996, and is horribly dated. It assumes a DOS environment. However, it provides a good overview of the topics, covers numerical integration, basic flight mechanics and control systems. The code examples are simplistic, reasonably complete, and do not assume the more common toolsets used for graphics today. As with most things, I think it is easier to learn the subject with a more basic reference.
A more advanced text (college senior, first year graduate school) is Principles of Flight Simulation provides excellent coverage of the breadth of topics involved in making a flight simulation. This book would make an excellent reference for anyone seriously interested in flight simulation as an engineering task, or for more realistic game development.
This is more a system design question/challenge, than a coding question.
Basically, I'm thinking of throwing together a Bejeweled-esque game on Facebook using just HTML, CSS, and javascript. This is mostly out of a desire to learn all the little caveats of FBJS via a non-trivial project.
So here's the deal. When developing for Facebook, actual API calls are very expensive; not only is there an additional POST to the Facebook servers, there's also the api call limit and throttling to worry about. In a nutshell, the fewer calls to Facebook the better. Combine this with the timing concerns of even this simple puzzle game, and there's good reason to aggressively minimize the number of callbacks in general.
Not being a security expert, here's the design I've come up with:
Embed a random seed in the game page.
Use that seed to create the game board (As well as additional pieces as needed).
Tweak the seed (xor, concatenate and hash, something like that) after each player move, based on time since last move. Edit: I should probably also include the actual move taken in mutating the seed.
Upon game completion post back the following: game start time, each move taken and when, and the client side results.
On the server, re-run the game with the given data, sanity checking the start time and move times, and then confirm that the results match.
To mitigate denial of service, the game itself will be tweaked to have a win by turn X condition.
To discourage the server being used as a "oracle" of sorts, a user posting back an invalid game will be banned for some constant time X (X being on the order of minutes).
This design requires three Facebook call per game played: one to store the random seed before the game is played, one to fetch it after the game is finished, and one to update the player's score if the game is valid.
What I'm trying to proof the system against is straight up score spoofing (http://...?myscore=999999999, or similar). I'd also like to mitigate "look ahead" attacks, wherein the user can tell what pieces are coming to the board next. Denial of service attacks on the hosting server (intentional or otherwise) should also be prevented.
The actual question, can anyone see a flaw in this design? Equivalently, is there a simpler design that meets my criteria?
Note: I am aware how unnecessary this probably is, but its an interesting question none the less.
I'm going to try and throw some numbers up here to futher illustrate my reasoning, these are pretty rough but I hope helpful.
Assuming a 10x10 game board, there are ~200 potential moves (swapping two adjacent pieces) most of which are invalid. Let's say there are on average 5 valid moves per "turn". If we constrain player actions to the frame of 50 to 30,000 milliseconds, there are 149,750 potential new hashes provided the "tweaking" algorithm doesn't discard bits; I feel confident in say there are at least 10,000 potential new hashes which must be calculated by an attacker assuming a cryptographically secure hash is used. If you throw a min-max algorithm at this, your decision tree explodes very quickly. Throw a game session expiration at this, say 30 minutes, and I believe the attack because equivalent in complexity to writing a little bot program to play for you which cannot reasonably be defended against.
If the client code calculates the next piece and you can't hide this algorithm very well, then some bored college student will figure this out. As a result, they will be able to generate a massive score and defeat your intentions.
I tend to say that it is impossible to do. Why? You cannot trust the client - I could just analyse and completly rewrite the client side code and return whatever values I like. The only way to protect you from cheating and all kinds of attacks is to perform the logic at the server - the client will just collect user input and display the server output. But this is completly against your design goal to minimize the number of server calls.