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On November 23, 2011 id Software supported its own tradition and published the source code of its previous engine.

This time, it's time idTech4 , which was used in Prey, in Quake 4 and, of course, in Doom 3. In just a few hours more than 400 forks of the repository on GitHub were created, people began to explore the internal mechanisms of the game or port it to other platforms. I also decided to participate and created a Intel version for Mac OS X , which John Carmack kindly advertised .

From the point of view of cleanliness and comments, this is the best release of the id Software code since the code base Doom iPhone (which was released later, and therefore commented better). I highly recommend that everyone learn this engine, collect it and experiment.

Here are my notes about what I understood. As usual, I cleaned them, I hope they save someone a couple of hours and encourage someone to study the code to improve their programming skills.
xially 5 october 2017, 14:04

"Something is missing here." I bet you, this idea will come first to your head, if you see my workplace in the office. There is no monitor and mouse. There is only a guy who threshes on the keyboard, looking as if into emptiness.

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It's just me, and my colleagues guarantee you that I'm usually not dangerous. I'm a programmer at the Vincit office in Tampere (Finland). And I'm blind. In this article I want to tell you a little about how I work.
xially 5 october 2017, 14:04

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One of the most important factors affecting the speed of development and the success of the project launch is the correct decomposition of the product manager idea into tasks for programming directly. How to do it right? Take the script of the new feature from the product and immediately start coding? First, write the acceptance tests, and then code that will provide their passing? And, maybe, shift everything to the shoulders of developers - and let them decide during the spam poker themselves?
Let's think about it and identify the problems that can arise in the process of separation of tasks, and the ways to solve them. In this post, we will discuss the basic principles of decomposition of tasks when working in a team. My name is Ilya Ageyev, I'm the head of QA in Badoo. Today I'll tell you how workflow affects decomposition, how different are testing and laying out tasks that arise as a result of decomposition, and what rules should be followed to ensure that the development process goes smoothly for all participants.
xially 3 october 2017, 11:58

image The meeting of the ISO WG21 C ++ Committee, which was held in Toronto from 10 to 15 July, ended today. Soon we will surely be waiting for detailed report from WP21 , and today the respected public is offered a post- "Warming up" with a discussion of the most interesting.

The results of the meeting are as follows: C ++ standard 17 is completed and will be published at the next meeting in November this year; the standard C ++ 20 has already acquired the first serious features - concepts ( concepts ), explicit generic lambda functions (explicit explicit lambdas < / i>) - and this is just the beginning.

The possibilities of the new C ++ standard 17 have been discussed more than once, about innovations written on Habr , conducted reports at conferences , so I will not bring them here again. It's no secret that the key feature of this release of C ++ was carrying the most "delicious" options into an uncertain future. Well, now we can say with certainty that many of the long-awaited "features" have moved to C ++ 20. The course taken for the stdlib extension has not gone away, so a much larger and rich set of functions can be expected from C ++ 20.
xially 3 october 2017, 11:55

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Everything should be stated as simply as possible, but not simpler.
 - Albert Einstein
To make the game entertaining and interesting, it is not necessary to make computer-controlled opponents smarter. In the end, the player must win. However, letting him win only because the manager of the opponents of AI is badly designed, is also unacceptable. Interest in the game can be increased if the mistakes made by the enemy are intentional. Carefully adjusting the mistakes of opponents, making them intentional, but believable, programmers will allow opponents to look smart and at the same time ensure the victory of the player. In addition, by monitoring AI systems and appropriately controlling them, you can turn situations in which opponents look silly into an interesting gameplay.

A common mistake in the development and implementation of AI systems in computer games is in too complex a design. The AI ​​developer can easily get carried away by creating an intelligent game character and losing sight of the ultimate goal, namely, creating an entertaining game. If a player has the illusion that a computer opponent is doing something clever, then it does not matter how the AI ​​(if any) creates this illusion. A sign of a good AI programmer is the ability to resist the temptation to add intelligence to where it is not needed, and to recognize situations in which more "cheap" and simple solutions are enough. Programming AI is often more like art than science. The ability to distinguish between moments in which cheap tricks are enough, and those where more complicated AI is required, is not easy. For example, a programmer, having full access to all structures of game data, can easily cheat by making the NPC omniscient. NPCs can know where the enemies are, where the weapons or ammunition lies, without seeing them. However, players often recognize such cheap stunts. Even if they can not determine the very nature of cheating, they may have a feeling that the behavior of the NPC is not like the natural.
MeLavi 29 september 2017, 12:02

image How does the JVM create new objects? What exactly happens when you write a new Object ()?
At conferences, it is periodically told that the allocation of objects uses the thread-local allocation buffer (TLABs): memory areas allocated exclusively to each thread, creating objects in which is very fast due to the lack of synchronization.
But how correctly to choose the size of TLAB'a? What to do if you need to allocate 10% of the size of TLAB'a, but only 9% is free? Can an object be allocated outside TLAB? When (if) is the allocated memory set to zero?
Having asked these questions and did not find all the answers, I decided to write an article to correct the situation.
Before reading it, it's useful to remember how some garbage collector works
MeLavi 28 september 2017, 8:23

The problem of most disputes about the problem of piracy is that in them "value" is estimated only in "monetary" dollars. Therefore, the problem is formulated like this: "When buying a game from us, the user spends money dollars. A pirated copy costs zero money dollars. So most people will pirate the game if they have a choice, so you need to stop them at any cost. "

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The dollar is famous for everyone.

This is the error, therefore, at least four currencies, and not one (monetary dollars) should be taken into account here.

I propose the following notation:


($ D) Monetary dollars
($ B) Temporary dollars
($ D) Headache paints [in the original Pain-in-the-butt-dollars]
($ Ч) Honesty Dollars

The player makes the choice to buy or spiratit game based on how much "each" service (and not product! ) costs in these four currencies, and also depending on the value for the player each of them.
MeLavi 27 september 2017, 13:23

The order of evaluation of expressions is determined by a particular implementation, except when the language guarantees a certain order of calculations. If, in addition to the result, evaluating the expression causes changes in the runtime, then the expression is said to have side effects.
MSDN
In our internal newsletter about C #, a regular question arises, which concerns the correct interpretation of such constructions:

a -= a *= a;
p[x++] = ++x;
In response, I ask:
Yes, who writes such a code with an imperturbable look? It's one thing when you write this, trying to win at the International COC Contest, or if you want to write a puzzle - but in both cases you realize that you are doing something non-standard. That, there really is someone who writes a - = a * = a and p [x ++] = ++ x; and thinks to himself "Shit, yes I write really cool code! "
KlauS 26 september 2017, 9:31

[A Friday translation of the 1999 article by one of the authors of the Thief game engine, Sean Barrett]
Unpleasant situation in "Sapper"
In this situation, I know that there are a lot of mines around me, but I can not determine where they are. Several mines can be in one of two places (pink or blue), a group of mines can be located in one of two combinations (light / dark green). In addition, there is still a difficult situation with "5" and "6" in the upper left corner, which I did not single out.

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Blue / pink - mutually exclusive pair, light / dark green - mutually exclusive group
"Sapper": logic or probability
In "Sapper" you can play in two ways: as a logical or probabilistic game.

Technically, probability implies logic. If you can logically prove that the mine must be in a certain place, then the probability is 100%. If you can prove that it is not in this place, then the probability is 0%. That is, in a sense, only probabilities are important to us. However, the player uses logical deduction to recognize such 100% situations. Sometimes, especially at low levels of complexity, it is enough to pass a level, no calculation of probabilities is required.

But there are situations when the whole logic of the world can not save you. A simple example is the situation with the "T", which can be seen down the center. It is slightly complicated by additional neighboring mines. (In the simplest case, "2" is replaced by "1", and "5" - by "3", so that the situation is symmetrical.)
KlauS 25 september 2017, 7:07

For testing, the code should be selected and copied directly from tweets . - approx. trans.

I recently found this tweet from <a href="https://twitter.com/FakeUnicode/"> @FakeUnicode < / a>. There was a JavaScript snippet that looked pretty innocuous, but displayed a hidden message. It took me some time to understand what was going on. I think that the record of the steps of my investigation may be of some interest to someone.

Here is the snippet:

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What would you expect from him?

Here we use the for in loop, which passes through the enumerable properties of the object. Since only the property A is specified, we can assume that the message with the letter A will be shown. Well ... I was wrong. : D
KlauS 23 september 2017, 8:40
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