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25. August 2011

 

I am currently working on a beginner level tutorial using SFML and just ran into a show stopper that I want to share.  If you are already using SFML 1.6, this is probably old news to you, but it caused me enough pain that I want to share it here.  Maybe someone in the future will find this on Google and they wont end up wasting a couple hours like I just did.

 

Anyways, I was developing away at my game and doing most of my work on my portable laptop, which has an integrated Intel chipset.  On occasion I did a little bit of work on my primary development laptop which has a higher end Radeon GPU and everything works fine.  Anyways, earlier this week Deus Ex: Human Revolution came out and PC gaming being what it is, I had to download and install the latest drivers.  Fast forward to today, I load up the project make a few changes and:

 

image

 

Completely hung.  Zero response whatsoever.  If I run the same application outside of Visual Studio, it requires me to kill it in Task Manager.

 

So I jump to the logical conclusion and figure it was something I changed recently in my code, so I start hacking and slashing out the changes until I am back to nothing.  Still hangs.  WTF?  Now I start hacking even more until the point I get to my main() consisting of a single return statement and still it hangs!  WTF x2?  Obviously at this point it’s a linker problem, and my lost likely culprit is SFML, so off to Google I go!

 

End result, yes, the dynamically linked version of SFML apparently has a bug with the OpenGL implementation of modern ATI drivers.  Yay.  Apparently it is only in the dynamic version of SFML, so you can switch to static linking and it will go away, but when writing a tutorial, this kind of added complication simply isn’t realistic.  That said, there is a work around and there is a fix... of sorts.

 

Apparently the problem is caused in atigktxx.dll and you can grab a copy that works here ( along with additional explanation ).  I haven’t an actual clue what the bug itself is ( it’s wayyyyyy outside my code ), but by including this copy of atigktxx.dll in your executable folder, it overrides loading the one that is installed on your machine, thus preventing the bug.

 

Oh, and although that post was in February and the fix is “coming soon”, the problem still occurs.  I do however believe this is fixed in the 2.0 version of SFML, but please don’t quote me on that!

 

So, long story short, if you are using SFML 1.6 and you want to support ATI cards with recent drivers, ship your game with atigktxx.dll in your executable directory.

 

Oh and moral of the story…  don’t always go blaming your code first!  I kow have a ton of damage to undo that I needlessly caused!  Moral number two…  ATI still suck at making drivers!

Programming ,

21. August 2011

 

When just starting out with Blender, figuring your way around the UI is probably the most difficult step.  One of the most difficult things to come to terms with is creating and closing windows.  This is something that changed massively from Blender 2.4 to 2.5, so a lot of the documentation out there is simply out dated.

 

This video shows you how to arrange Blender exactly how you want it.  Once you figure out the way things work, it is amazingly power, but it can be confusing at first.  The video is of Blender 2.59 and is shot at 1080p for maximum clarity.

 

 

Customizing Blender 2.59’s User Interface

EDIT (8/25/2011): Click here for Vimeo video.

Art

17. August 2011
 

I’ve been a little to focused on C++ I completely missed and forgot to mention that a new release of Blender, Blender 2.59 was release (*cough* 3 days ago *cough*). A ton of new bug fixes, include one specifically for exporting to Unity, have been addressed.  Additionally added support for 3D Mouse(s?), Custom Keymapping, an Ivy and Tree generator.

 

Click here to download now.

 

I will check shortly to see if it works “out of the box” with Unity.

 

EDIT: 8/17/2011  Nope, default export didn’t work.  Can’t say I’m shocked.

EDIT2: User woodn has provided an updated importer script.  Download it, extract the .py file and extract it to your Unity install directory /Editor/Tools folder, overwriting the existing importer.

After updating the import script it would successfully import dae files, but wouldn’t automatically process .blend files, at least for me.

Art ,

16. August 2011

 

Well if you are a student that is, yes!  Autodesk has made an absolute ton of their programs available on a 36 month license for students.  That said, there is a very big but… and we will get to it in a moment.  First off, here are the applications they made available:

 

AutoCAD®
AutoCAD® for Mac
AutoCAD® Civil 3D®
AutoCAD® Electrical
Autodesk® Alias® Design
Autodesk® Alias® Automotive**
Autodesk® Ecotect® Analysis
Autodesk® Inventor® Professional
Autodesk® Maya®

Autodesk® Moldflow® Adviser
Autodesk® Mudbox™
Autodesk® Revit® Architecture
Autodesk® Revit® MEP
Autodesk® Revit® Structure
Autodesk® Simulation Multiphysics 
Autodesk® Smoke®
Autodesk® Softimage®
Autodesk® 3ds Max®

That is a pretty awesome list and making them available to students for free is an absolutely brilliant idea for locking in future users down the road.  Now here are the buts…

 

If you are creating a game, you are violating the license.  This license is explicitly for personal learning.  The personal part even excludes use in a lab or classroom environments, however more to the point, if you want to use the software to work on a game that is going to be distributed ( even freely ) you are violating the license!  If you use the software to create graphics for a website, you are violating the license.  In a nutshell, legally, you can only use the software to learn or post your works to Autodesk’s community.  Now posting your work to a 3rd party like DeviantArt for non-commercial gain, I do not know the legal status of that.

 

As to who qualifies as a student, I will let Autodesk themselves answer that.

 

A faculty member is an employee at a primary or secondary educational institution or any degree-granting or certificate-granting educational institution or any learning, teaching or training facilities and who upon request by Autodesk is able to provide proof of such status.

A student is an individual enrolled at a recognized degree-granting or certificate-granting educational institution for three (3) or more credit hours in a degree-granting or certificate granting education program or in a nine (9) month or longer certificate program, and upon request by Autodesk is able to provide proof of such enrollment.

An Autodesk Assistance Program participant is either a veteran or unemployed individual who has previously worked in the architecture, engineering, design or manufacturing industries, completed the online registration for the Autodesk Assistance Program, and upon request by Autodesk is able to provide proof of eligibility for that program.

 

 

So if you are thinking the cost of your game just went way down because you are a student, you are completely wrong.  However, if you wanted easy free access to learn and evaluate various Autodesk products, you will love this opportunity.

15. August 2011

 

This began life as a post here but it became long enough and IMHO important enough, I am going to clean up the spelling a bit and repost it here.  It was in response to a fairly new developer with a question about class design.

 

 

This is one of those things that is nearly impossible to explain in a post, or hell, short of a small book.


But generally ( and yes, there are exceptions, thousands and thousands of exceptions ) you want to decouple your objects from each other as greatly as possible. You also want to keep code as self contained as possible, again, with thousands of exceptions.

 


A lot of the time when you are designing your classes ask yourself "If I changed this class, how many other aspects would need to be changed as well?" Then go about breaking those dependencies where possible. If two classes don't really need to know about each other, break that dependency. If two classes share 90% of their functionality, derive from a common base class.

 


On the other hand, you have to let common sense be a factor. One really common reason to abstract away your classes into engines and various components is so you can make switches later. For example, if you are using SDL, but want to be able to switch over to SFML at a later date, it's common to make a Renderer class, and an intermediary class over all the various objects like Bitmaps and Sprites, that both SDL and SFML provide so you can transparently change Renderers without making a code change. Reality is though, for 90+% of projects, this is just an added layer of complication and work that will never ever be used. This is where common sense has to come into play. Yes, from a purely object-oriented perspective, it is a very "pure" design that implementation details are abstracted away. From a practical and getting shit done sense, it's just a stupid waste of time.

 


This is where we get to the next sticking point and another area where new developers ( and experienced developers! ) get it really wrong most of the time. Global variables. See, when a new developer learns about global variables they seem like a godsend, as then you frankly don't have to design classes at all, just make everything globally available! This in a very short while makes extremely unreadable and maintainable code. Other new ( and experienced developers ) have heard about this and had it drilled into their heads that GLOBALS ARE BAD!!!! and react accordingly. Ironically enough, 9 times out of 10 this seems to always result in the same discovery... the Singleton. If you haven't yet, some day you will discover the singleton pattern and you will think it is the answer to your prayers. It's not a global, it's an object!!! Actually no, it really is just a global with a pretty layer of object oriented goop wrapped around it(**). Then you will encounter another group of people that will yell from the mountains SINGLETONS ARE BAD!!!! Which in the end leads you to engineering half a hundred "Manager" or "Adapter" classes to eliminate your dependencies on global variable and singletons. All the while, no work is getting done on your game.

 


Now it's time to let you in on a dirty little secret. Globals aren't bad, they are actually pretty frigging useful and important. The most important thing is, DO NOT ABUSE THEM. That is it. Chances are, you are going to have some form of global object, like perhaps a Game, App or World class, this is completely reasonable. On top of that you are going to run into code that needs to be globally accessed, such as your Audio class or Event class, which is also quite reasonable. It simply does not make sense to pass in an Audio class to say, a GameEvent, because that game event might on occasion need to play a sound. There are quite literally only a handful of things that should be made globally available but if it makes sense to be globally available, make it globally available.

 


But here is where the design gets tricky again, if you are making something globally available, do not make the relationship two-way, or at least not unless the two-way relationship is completely generic or via an interface. For example, if you have a game engine ( globally available ), and that game engine has a (globally available ) event queue, that at some point a game object needs to add events to, make sure that the event queue has the most absolutely minimal requirement to know anything about the game object and that the game engine itself needs to know absolutely NOTHING about the game object, as this is where your design can start to fall on it's face.

 


One last general rule of thumb when dealing with globally available classes, make them static whenever possible, it will lead to less potential hazards. Additionally, when make global objects provide access to other global object ( for example Game::SoundManager ), use accessor methods and const whenever possible. Keep all allocation and de-allocation specifically in the realm of the containing object.

 

 

 

 

 

 

 

 

 

 


(**) There are actually more to singletons than just object oriented globals. Yes, Singletons are global in scope but they have a couple very important properties. First of which is deferred allocation, meaning the Singleton isn't using memory until the first time it is used, unlike a traditional static variable. Additionally, a Singleton can be sub-classed as a mechanism of providing a single interface to potential disparate code bases, so for example you could have a Renderer::GetInstance(), which is sub-classed as OpenGLRenderer or DirectXRenderer, which will provide your code with a single global runtime determined instance. If you don't understand this paragraph, that’s completely fine, I'm just throwing it out there as a caveat so my over simplification of a Singleton isn't misleading... they do have their uses.

Programming, Design

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