I am in the process of building a mobile game with Corona SDK, which is based on Lua. Until now i didn't need any help but this time I can't seem to find the cause, and I've been searching for it for hours.
It's one of those timer problems, where, after leaving, removing, and revisiting the scene, items that are spawned within a loop just multiply themselves every relaunch. More specificly, everytime a "forbidden" collision happens, which leads to the relaunch, according to my onCollision function.
What I already corrected after hours of strenuous research :
--the code inside the onCollision function is now inside the "began" phase,
so that can't cause the multiplication
--the scene phases are also correctly used
--transitions and timers are all canceled right before the relaunch
Since the code would be too long for you to look through, I'd rather ask for some hints :
What do you have in mind can cause such problems, besides what I already mentioned.
I appreciate every answer! Thanks alot.
The above comments are valid, it is going to be hard to diagnose the problem without being able to look at the code.
In the past, I have found it very helpful to name all my objects when dealing with collisions, so when a collision happens I know what objects caused it and it is very helpful for debugging purposes.
It looks like you have an issue with how you are starting the scene and deallocating resources when the scene ends. You may want to start/stop physics when the scene leaves and comes back, but without code I can't give a concrete answer.
Related
I have a small sample, written in C using the Vulkan API.
I followed the guide vulkan-tutorial up to the end of the Uniform Buffers chapter.
While this tutorial is written in C++, I am using plain C, thus my codes differs slightly in some places.
In addition I have opted to use DynamicState instead of recreating the entire GraphicsPipeline each time the window is resized. In addition I changed both to always use VK_PRESENT_MODE_FIFO_KHR.
It seems that I made some mistake adapting the code, because I get a lot of ghosting and choppiness from the rotating quad, as can be seen here: video.
The left is my result and on the right is the original.
Theories and observations:
It seems, that my one updates much slower, like at half framerate. But I measured that the UBOs are updated at the same frequency as in the original.
Another cause could have been, that Swapchain Images are rendered in the wrong order. Like old images are being presented without being rerendered. I tried to rule out any synchronization problems by calling vkDeviceWaitIdle in each iteration of the main loop. It did not improve the situation.
If you look closely, you can see that the original has a little amount of ghosting as well. I think this can be attributed to the monitor. It does not explain why the issue is so much more pronounced with my program.
I reverted back to non dynamic Viewports, Scissors and turned resizing off altogether, to rule it out. It was not the cause.
The C code uses cglm as opposed to glm. I have swapped glm out in the original. It is not the cause.
An interesting observation: when the window is resized quickly, the issue goes away for the duration of the resize operation.
I have searched quite extensively for the problem. But haven't found anything. I don't really expect to debug my code for me. Unless you want to.
But maybe you are familiar with the vulkan-tutorial code base and have an Idea what might have caused it.
UPDATE:
I still haven't figured out the problem. But in an attempt to reproduce the problem with more concise code I rewrote everything from scratch but wasn't able to reproduce the problem. I have now added in all the features the faulty version had and it is still working fine.
I'm brand new here, and also to Lua, so please bear with me...
I'm building an Airport in Minecraft, with my kids. I'm an overachiever and a dreamer, and at some point, my brain decided it would be a FANTASTIC idea to add in a cosmetic element that I have absolutely NO idea how to do. Smart, right?!
See, I got it in my head that I want to have display screens in our Airport that show the flight information of incoming/outgoing flights. Fast forward to my discovery of the Opencomputers mod for Minecraft, a few hours of watching tutorials on how to operate it, and thus began my search for knowledge of that which is the Lua language. Fortunately, I have a wee bit of coding experience (thanks to my college days) and I picked up the very basic of the basics. (It seems similar to C.) I've gleaned just enough to accomplish the bigger part of my goal: I've managed to write the bare bones of the program I dreamed up, and it works...for the most part. (I still need to figure out some redundancies and such...all in good time.)
But...it's so very plain, and not fancy at all. It doesn't look even remotely like what I was picturing in my head, and this simply will not do. So now I am on a quest to discover how to format the output of my program and make it look fantastic...or at least, as close as I can get it to what was in my head. I have managed to figure out how to change the gpu screen colors (foreground, background) so that is why it's blue/white. But it's not quite what I wanted, and it resets if the system is turned off. My goal is to change the format of the program output itself, not just the Opencomputers screen block. I've googled this until I'm blue in the face, and I have pored over forums and code tutorials and the like...only to fail at finding the information I need. It's possible that I've passed up the answer, simply because I'm still very new to the language, but that's another good reason for me to be here, right?
And so, I turn to you, O Great Dwellers of the Interwebs, the Keepers of Vast Programming Knowledge, for assistance. Please, pretty please, help me make my program look awesome. My kids just may think I'm the coolest Mom on the planet, and that would be more than fantastic...Not to mention we'd have one kickass airport to play around in. :)
Here's what you'll probably want to know:
First, This pic is what I want, (on the left) and what I have (on the right).
And here is the code for my program: http://pastebin.com/60nPfpB8
I apologize up front for all of the noob mistakes that my code is more than likely riddled with. I haven't figured out yet how to make the functions repeat themselves, or a good way to utilize a 24 hour clock for the "time" function. So any suggestions there would be welcome as well.
Thank you for taking the time to read, and I appreciate any help I can get with this. :)
A friend of mine is beginning to build a NetHack bot (a bot that plays the Roguelike game: NetHack). There is a very good working bot for the similar game Angband, but it works partially because of the ease in going back to the town and always being able to scum low levels to gain items.
In NetHack, the problem is much more difficult, because the game rewards ballsy experimentation and is built basically as 1,000 edge cases.
Recently I suggested using some kind of naive bayesian analysis, in very much the same way spam is created.
Basically the bot would at first build a corpus, by trying every possible action with every item or creature it finds and storing that information with, for instance, how close to a death, injury of negative effect it was. Over time it seems like you could generate a reasonably playable model.
Can anyone point us in the right direction of what a good start would be? Am I barking up the wrong tree or misunderstanding the idea of bayesian analysis?
Edit: My friend put up a github repo of his NetHack patch that allows python bindings. It's still in a pretty primitive state but if anyone's interested...
Although Bayesian analysis encompasses much more, the Naive Bayes algorithm well known from spam filters is based on one very fundamental assumption: all variables are essentially independent of each other. So for instance, in spam filtering each word is usually treated as a variable so this means assuming that if the email contains the word 'viagra', that knowledge does affect the probability that it will also contain the word 'medicine' (or 'foo' or 'spam' or anything else). The interesting thing is that this assumption is quite obviously false when it comes to natural language but still manages to produce reasonable results.
Now one way people sometimes get around the independence assumption is to define variables that are technically combinations of things (like searching for the token 'buy viagra'). That can work if you know specific cases to look for but in general, in a game environment, it means that you can't generally remember anything. So each time you have to move, perform an action, etc, its completely independent of anything else you've done so far. I would say for even the simplest games, this is a very inefficient way to go about learning the game.
I would suggest looking into using q-learning instead. Most of the examples you'll find are usually just simple games anyway (like learning to navigate a map while avoiding walls, traps, monsters, etc). Reinforcement learning is a type of online unsupervised learning that does really well in situations that can be modeled as an agent interacting with an environment, like a game (or robots). It does this trying to figure out what the optimal action is at each state in the environment (where each state can include as many variables as needed, much more than just 'where am i'). The trick then is maintain just enough state that helps the bot make good decisions without having a distinct point in your state 'space' for every possible combination of previous actions.
To put that in more concrete terms, if you were to build a chess bot you would probably have trouble if you tried to create a decision policy that made decisions based on all previous moves since the set of all possible combinations of chess moves grows really quickly. Even a simpler model of where every piece is on the board is still a very large state space so you have to find a way to simplify what you keep track of. But notice that you do get to keep track of some state so that your bot doesn't just keep trying to make a left term into a wall over and over again.
The wikipedia article is pretty jargon heavy but this tutorial does a much better job translating the concepts into real world examples.
The one catch is that you do need to be able to define rewards to provide as the positive 'reinforcement'. That is you need to be able to define the states that the bot is trying to get to, otherwise it will just continue forever.
There is precedent: the monstrous rog-o-matic program succeeded in playing rogue and even returned with the amulet of Yendor a few times. Unfortunately, rogue was only released an a binary, not source, so it has died (unless you can set up a 4.3BSD system on a MicroVAX), leaving rog-o-matic unable to play any of the clones. It just hangs cos they're not close enough emulations.
However, rog-o-matic is, I think, my favourite program of all time, not only because of what it achieved but because of the readability of the code and the comprehensible intelligence of its algorithms. It used "genetic inheritance": a new player would inherit a combination of preferences from a previous pair of successful players, with some random offset, then be pitted against the machine. More successful preferences would migrate up in the gene pool and less successful ones down.
The source can be hard to find these days, but searching "rogomatic" will set you on the path.
I doubt bayesian analysis will get you far because most of NetHack is highly contextual. There are very few actions which are always a bad idea; most are also life-savers in the "right" situation (an extreme example is eating a cockatrice: that's bad, unless you are starving and currently polymorphed into a stone-resistant monster, in which case eating the cockatrice is the right thing to do). Some of those "almost bad" actions are required to win the game (e.g. coming up the stairs on level 1, or deliberately falling in traps to reach Gehennom).
What you could try would be trying to do it at the "meta" level. Design the bot as choosing randomly among a variety of "elementary behaviors". Then try to measure how these bots fare. Then extract the combinations of behaviors which seem to promote survival; bayesian analysis could do that among a wide corpus of games along with their "success level". For instance, if there are behaviors "pick up daggers" and "avoid engaging monsters in melee", I would assume that analysis would show that those two behaviors fit well together: bots which pick daggers up without using them, and bots which try to throw missiles at monsters without gathering such missiles, will probably fare worse.
This somehow mimics what learning gamers often ask for in rec.games.roguelike.nethack. Most questions are similar to: "should I drink unknown potions to identify them ?" or "what level should be my character before going that deep in the dungeon ?". Answers to those questions heavily depend on what else the player is doing, and there is no good absolute answer.
A difficult point here is how to measure the success at survival. If you simply try to maximize the time spent before dying, then you will favor bots which never leave the first levels; those may live long but will never win the game. If you measure success by how deep the character goes before dying then the best bots will be archeologists (who start with a pick-axe) in a digging frenzy.
Apparently there are a good number of Nethack bots out there. Check out this listing:
In nethack unknown actions usually have a boolean effect -- either you gain or you loose. Bayesian networks base around "fuzzy logic" values -- an action may give a gain with a given probability. Hence, you don't need a bayesian network, just a list of "discovered effects" and wether they are good or bad.
No need to eat the Cockatrice again, is there?
All in all it depends how much "knowledge" you want to give the bot as starters. Do you want him to learn everything "the hard way", or will you feed him spoilers 'till he's stuffed?
This is an odd one. I am making a app that is kind of a game, and I wanted to have a shooting starburst effect. I made it one evening and it all worked well, until I noticed that my browser was eating over 300 megs of ram, eating 1 meg every 5 seconds, mainly when the starburst would happen.
Here is an example stripped down to just the starburst:
http://www.sizzln.com/example.htm
First thought, I am not removing the objects or still have references somewhere. I am placing each generated star into a Canvas, but I am removing old starts every 3 seconds. I do have a lot of DoubleAnimations as well, but I even have a callback to set everything to null.
Here is the weird part, if I convert it to WPF it doesnt happen, if I run it inside of Silverlight Spy 3, it doenst happen. If I take a Heap Dump using WinDbg and SOS.dll, it reports that it should only be using between 1.8 and 3 MBs of ram.
I have the GC running every 3 seconds to cleanup, but it never has any effect. I can see in the heapdump that many objects are now deleted, and I always get back to 1.8 meg or so after a GC, but the memory shown in Task Manager just keeps going up.
I dont know what to do, I think I am carefully removing the objects unless my Heap is not being honest.
Are you running Vista or Win7? It sounds like the OS is not reclaiming memory, as it shouldn't unless it needs to.
It may also be that the Silverlight GC doesn't free its buffers, on the assumption that the memory may need to be reallocated soon.
In either case, it doesn't sound like anything to worry about, as long as the profiler says your program only uses 1.8MB after the GC runs.
I just briefly looked over your code. You have a lot of places where you hook into events (+=), but never unhook (-=). These are hard references and therefore won't ever be collected if they are ultimately connected to a root object.
OK I am going to sorta answer my own question. Silveright doesn't have the handy "BeginAnimation" method, so I found online a quick way to add an extension to do basically the same thing, it did this by creating a storyboard and starting it.
However, it just stayed there, I dont exactly know what it was being connected to either. Calling Stop() on it after it finishes fixed my memory issue.
One odd side effect is I have to be careful when I call the stop method, when creating so many storyboards it seemed to get a bit confused and it would cause some of the objects to reappear, even after they were removed from the control.
I'm running into a strange issue on Vista with the Performance monitoring API. I'm currently using code that worked fine on XP/2k, based around PdhGetFormattedCounterValue(). I start out using PdhExpandWildCardPath to expand the counters (I'm interested in overall network statistics), the counters I'm looking at are:
\\Network Interface(*)\\Bytes Received/sec
\\Network Interface(*)\\Bytes Sent/sec
\\Processor(_Total)\\% Processor Time
The problem is that on their first call they return PDH_INVALID_DATA, I don't think this is a problem, since if I query it again I will start getting data without the error. The problem is this - while the processor time is worked exactly as expected, neither of the network interface counters are returning anything - just 0 all the time. I verified using Perfmon that they are reporting data normally, so I'm at a loss as to what might be the issue. I caught this at MS:
http://support.microsoft.com/?scid=kb%3Ben-us%3B287159&x=11&y=9
But I'm not interested in multi-language for my task, so I don't think this is relevant. I will see if I can come up with some basic code showing exactly what I'm doing, but nothing is returning anything strange, and it worked on XP/2k, so I suspect something changed under the hood. Thanks!
It turns out the issue was that the network interfaces are both wildcards, whereas the Processor one is actually already rolled up by the performance monitoring. What I didn't realize was that it PdhExpandWildCardPath didn't return something directly usable by PdhAddCounter. By this I mean that if ExpandWildCard returns 3 expanded matches, they come back as a null separated strings - I understood this, but I had assumed that AddCounter would be effectively create a counter containing all three. Nope, reality is I needed to break up each path and request it individually from AddCounter, then roll up the results manually when I get them.
Hopefully this helps someone else to avoid the same mistake I made with less frustration. ;)