9/Jul 2008
By admin
7 min. read
One of the most basic issues in the game development is: how do we identify “things”. Thing can be, well, anything - logical object, resource, level, entity, animation etc. The most straightforward way is of course to name them and identify with strings (tags). So, you have “texture_leaves0”, “badguy_01” and so on. This solution has two advantages - it’s dead simple and contains bonus useful info. Unfortunately, it has also lots of problems.
2/Jul 2008
By admin
2 min. read
Recently I’ve been playing with SQLite for my new experiment (more about it later, when I’m done). It’s one sweet little library, integrating it and coding a quick C++ wrapper took me maybe 1 hour. As authors claim themselves - it just works. I’ve only one tiny complaint, though. As I mentioned before, all my home projects are compiled with maximum warning level and warnings treated as errors. Sadly, this seems to break roughly 50% of external libraries, including SQLite (trying to compile sqlite3.
28/Jun 2008
By admin
1 min. read
(idea shamelessly stolen from Jim Tilander and Power of Two Games. Not fullblown post, just random notes from time to time, as I learn/think about it)
how to easily make sure all our header are self-contained? Include header as the first one in corresponding .cpp file. For example (ThreadPool class, ThreadPool.cpp file): #include "thread/ThreadPool.h"
#include "thread/LockFreeMemList.h"
#include "thread/LockFreeQueue.h"
#include "thread/Task.h"
#include "thread/TaskGroup.h"If my coding standard could only have single rule - it would be this one.
21/Jun 2008
By admin
3 min. read
Soooo, in case you haven’t noticed - Firefox 3.0 has been released recently. I gave it a try and quickly came to the conclusion it’s another proof that any software package can reach certain level after which modification can do more harm than good. Sure, version 2 had some problems with memory (see Stuart Parmenter’s blog), it probably didnt conform to standards perfectly and had some other problems, but I really liked it.
16/Jun 2008
By admin
1 min. read
As promised, I performed some tests of my thread pool on quad-core machine. Difference between lock-based and lock-free version is bigger (than on dual core), but definitelly it’s not as significant as one could guess looking at results in Intel Thread Profiler (higher concurrency, smaller contention). The most important speed-up can be gained by letting main thread help workers when it’s waiting anyway (50 fps ‘> 61 fps), but this one is independent from other modifications and can be applied to lock-based version as well.
12/Jun 2008
By admin
6 min. read
Few days ago I decided to have closer look at my multi-threaded experiments, mainly to check if there really is any kind of difference between code based on locks and lock-free version. Downloaded evaluation version of Intel Thread Profiler and gave it a try. Especially for this experiment, I modified scenario a little bit. Mandelbrot is not the best test as tasks take relatively long time (with selected number of iterations one ‘frame’ would take over 2 seconds).
3/Jun 2008
By admin
3 min. read
Subject is mainly an excuse to list some of my favourite productions. In general, I’ll try to talk about world firsts/world records in demos, tho. World first is just an effect that has never been done before (in realtime). Let’s start with one of the first demos I’ve seen and remember to this day. It’s from Amiga, which had a very active scene at that time. I used to visit my mate, who was swapper in Casyopea and he’d show me a demo or two sometimes.
1/Jun 2008
By admin
3 min. read
Just some random notes, that are too short for their own entry, but still rather interesting:
Stack Overflow - new initiative by perhaps two biggest celebrities in the programming blogging community - Jeff Attwood and Joel Spolsky (even if he insists he’s not blogging, just writing essays). In terms of marketing it’s blogging equivalent of Marlon Brando and Jack Nicholson doing movie together. It’s also my first serious contact with podcasts.
28/May 2008
By admin
1 min. read
If you’ve been programming POSIX threads (or Java, C#, D…), chances are you’ve used condition variables. It’s also probable that after that you switched to Win32 and found nasty surprise - no “native” condition variables here. Of course, they can be implemented with help of other synchronization primitives, but it’s not for the faint-hearted (I’ve to read this article in small portions, like 10% at a time, otherwise my head starts exploding).
27/May 2008
By admin
4 min. read
I’ve been reading “The Algorithm Design Manual” (Steven S. Skiena) recently and I have to share with you one of the chapters, just because it’s too cool.
In “The Witcher” we have the following problem: we’ve plenty of attack animations, most of them dynamic (ie, the character is moving forward) and not so many damage animations. Most of the attack consist of multiple hits. The problem is with synchronizing damage and attack animations (so that our opponent moves back roughly at same pace and similar distance as we move forward, playing his damage animations at the same time).
17/May 2008
By admin
6 min. read
For the last days (weeks) apart from playing GTA IV (mainly) I’ve been improving my thread pool class. I decided to implement system similar to the one described by Ian Lewis from Microsoft in “Getting More from Multicore” from GDC2008. Basically, it’s an extension of my system, it gives greater control over inter-task dependencies. Task cannot be started until all tasks it depends on are finished. In theory it’s rather easy, I just provide extra scheduler thread that deals with incoming tasks, if any of them is “ready” it’s put in a priority queue (priority in the most simple case is number of dependents), so that it can be processed by worker threads.
9/May 2008
By admin
1 min. read
One of the simple measurements of game quality (popularity?) is how much do we talk about it during lunches. For a few days it’s been all about GTA IV. It hasnt yet reached level of WOW discussions few years ago (some of our mates actually threatened they would stop eating with us) but it’s close. Game’s great and at the same time it has soo many funny bugs. It’s understandable with project of this scope and freedom but still hilarious at times.
30/Apr 2008
By admin
2 min. read
Found an interesting article at Escapist. It’s a story of Muckyfoot, now-defunct gamedev company founded by some of the Bullfrog veterans. (Side note: the power of the original Bullfrog team is really impressive… they went on to found Lionhead, Elixir, Muckyfoot, Media Molecule (that’s ex-Lionhead, but still counts :) and some more… Think what they could achieve were they still together). As usually, when written by someone from “outside” it’s a little too poetic/melodramatic at times, but still worth reading (I love the bit where Gary Carr and Fin McGechie were told off for running in the corridors of EA… what’s that?
28/Apr 2008
By admin
3 min. read
There are several approaches to implementing a hash map. Main difference is in the way we handle collisions between entries falling the the same bucket. Probably the most popular and elegant is “chaining”, where for every slot we have a linked list of entries. In case collision we just enqueue entry in list for correct bucket. Variation of this method is used for example in MSVC’s library.
I implemented it in the first version for RDESTL as well, just because it was the most straightforward.
23/Apr 2008
By admin
2 min. read
I think I’ve already posted links to some videos from Google Tech Talks, but I’ve been catching up recently and found some other interesting movies. They all have a nice, distinct geek spirit… Where else can you find 50 minute presentation about the beauty of quicksort implemention?
Three Beautiful Quicksorts (Jon Bentley) - who said sorting is boring?
How To Design A Good API And Why It Matters (Joshua Blooch),
19/Apr 2008
By admin
1 min. read
OK, so how does this snippet work? There’s a function that takes array of N elements as an argument. It returns an array of N chars. Assuming sizeof(char) == 1, size of the return type for this function is N. There’s no function body, because it’s not needed, function is never called.
On the other note, we’ve been hit by the Reddit Effect. Of course, in this case it wasnt a problem of breaking the server, but it screwed all my stats.
15/Apr 2008
By admin
1 min. read
Mario would be proud. (…they could spare this comment about fat kids, tho).
12/Apr 2008
By admin
2 min. read
(or one more reason to love C++).
Problem: how to find out number of elements in a C++ array? The most popular form is probably: #define RDE_COUNT_OF(arr) (sizeof(arr)/sizeof(arr[0]))
...
Foo myTab[10];
size_t numElems = RDE_COUNT_OF(myTab);
assert(numElems == 10); It’s being widely used, however most people do not realize the potential danger with this small piece of code.
Imagine that one day we decide to change our static array to dynamically allocated block of memory: Foo* myTab = new Foo[numNeededFoos];
size_t numElems = RDE_COUNT_OF(myTab); // Huh?
8/Apr 2008
By admin
4 min. read
(yeah, the title is stupid)
After I got a little bored with memory experiment I moved on to something more interesting - lock free containers and multi-threaded tasks/jobs. This is all rather new to me, so it seemed like an interesting stuff. What we have here is simple system for distributing independent tasks on multiple threads. Basic system was inspired by Industrial Light&Magic’s code from OpenEXR. Main difference is that attached snippet is basically lock-free (it only locks when initializing threads at the very beginning).
5/Apr 2008
By admin
9 min. read
You may remember my proof-of-concept experiment - MemTracer. It started as a hobby project, but recently I had chance to test it in a real world application. It quickly turned out there’s a big difference between my simple test program and full blown game performing hundreds of memory operations per second.
Below you can find list of conclusions I drew from this experience:
realtime analysis is next to useless.