Tom Miller's Blog : XNA

Dream Build Play 2009 finalists…

tmiller — Fri, 04 Sep 2009 03:00:26 GMT

Once again, the Dream-Build-Play 2009 competition has provided a ton of great games. The finalist this years have been announced here, and the winner will be picked at PAX in just a few short days.

The talent and ability the people making these games and the quality of the entries we get never ceases to amaze me.

My blog is a constant source of new and exciting information…

tmiller — Thu, 03 Sep 2009 09:33:13 GMT

It’s been over a year since my last post, and despite my many promises to myself (and anyone who still reads this thing), I never seem to find time to post here. Well, other than right now, since I obviously am doing it now.

A lot has happened since my last post. We shipped Game Studio 3.0 and opened up the Indie Games on Xbox Live, although it was so long ago, it wasn’t even *called* Indie Games back then, it was called Community Games. I’m sure everyone has heard about it by now, and I still think it’s awesome that you can sell games you’ve created. Then again, we also shipped a completely new version since then as well in Game Studio 3.1! Wow, I really am behind aren’t I? We added cool new stuff like Avatar support in that version.

I even completely forgot about my annual Aprils Fools post! Of course, I didn’t really come up with a cool topic for that anyway. I’d make up something outlandish now, but that wouldn’t be nearly as effective since it’s September.

Speaking of Indie Games though, I think I’ve finally decided the game I’m going to write to ship there. Of course, my idea is way too ambitious for my artistic talent (read; zero), and I have no idea where I’m going to find the time to actually write it, but no matter. I will finish it and ship it and suffer the ridicule of the masses!

Maybe that will even give me the impetus for writing more here. We can hope… If not, lets hope I’ll remember to write something sooner than the next two versions of Game Studio.

Community Games!

tmiller — Wed, 21 May 2008 01:50:00 GMT

For those of you who don't read the XNA Team Blog the Community Games on Xbox LIVE feature has gone into a beta release!

Plus, the web site looks much cooler now.

So, what does this mean? It means that premium members can create a game, submit it for peer review, and then have it available on Xbox LIVE. There's also a new starter kit, a 2D RPG Game. There is plenty of information and new cool stuff on the new web site, so go check it out!

I just tried to use four render targets on my Xbox 360 and it failed!!

tmiller — Sat, 01 Mar 2008 01:06:00 GMT

Dear Mr Miller, you suck. I'm running in 1080p resolution, and needed to have four simultaneous render targets, and a depth buffer, and I can't do it.

Now, to be fair, I didn't actually receive a message like that, but I could see it happening (and I've gotten some similar). One of the features that we added this last release was the ability to use multiple simultaneous render targets on Xbox (up to four of them). However, this isn't without restriction. All render targets that will be used on the device need to fit within the EDRAM (a 10MB chunk of memory). This includes the depth buffer if it exists. EDRAM isn't very big at all.

Let's take a look at an example. Your Xbox is rendering in wide screen 720p mode with a resolution of 1280x720. You set your game to run at this exact same resolution with a surface format of Color (32bits) and a 32bit depth buffer as well. You also turn on 2x multisampling because you hate jaggies like the rest of us. All of this data needs to fit into EDRAM, so let's see how big we are. Each pixel in the back buffer will be 8 bytes (32bit for color, double it for multisampling). There are 1280x720 pixels, so the back buffer will be taking up approximately 7.3MB of memory. The depth buffer is the same size, so that's another 7.3MB, and we're looking at a total of almost 15MB of data we need to store in our 10MB chunk of memory.

As you can see, even this simple scenario we overstepped our bounds. Luckily, we have a mechanism (called "tiling") that allows us to work with this data anyway. We essentially break our large 1280x720 set of pixels into a series of smaller sets of pixels that *do* fit within the memory constraints. In the example above, the back buffer could be broken down into two separate "tiles" of size 640x720 with 2X multisampling, and things would work just fine. With only two possible consumers of this chunk of memory in version one (the back buffer and the depth buffer), you could easily fit the largest possible back buffer sizes within this chunk of memory.

In version two though, we allow up to five consumers of this memory (four simultaneous render targets and the depth buffer). The memory is broken up equally by all consumers, so in the maximum case, each render target and buffer has to fit within 2 MB of EDRAM. You can imagine if I called 10MB small what I think about 2MB. I'm sure you could just think "Well sure Miller, that's fine, but we could just create hundreds of little tiles and make it all fit."

There are two big issues with this. First, performance would be horrible. Each tile that is rendered actually will have your *entire* scene rendered on to it, then the results of the tiles glued together. In a complex scene this could add up very very quickly. Second (and more importantly) we only allow a maximum of 15 tiles to be created at one time. If your render target or depth buffer cannot fit inside 2MB of memory with 15 tiles or less, you will fail.

Knowing that, what size of render targets can you make? What if you have a 2048x2048 render target (surface format of Color) with no multisampling? Would that fit if you had four of them at the same time? A quick and dirty way of figuring it out would be this:

2048 * 2048 = 4MB * 4bytes (color) = 16MB (total amount of memory needed) / 2MB (maximum size) == 8

So, you'd need 8 tiles for this buffer to render correctly, 8 is less than 15 so you'd be safe. What if you added 2x multisampling though?

2048 * 2048 == 4MB * 8 bytes (color+ms) == 32 MB (total amount of memory needed) / 2MB (maximum size) == 16

Nope, 16 tiles is too many, this wouldn't fit. What if you didn't have a depth buffer though? Depth buffer counts as a buffer in the EDRAM so without it, you'd have 2.5MB per surface available:

2048 * 2048 == 4MB * 8 bytes (color+ms) == 32 MB (total amount of memory needed) / 2.5MB (maximum size) == 13

13 tiles, you'd fit again!

It's also important to point out that not all tiles are created equal. Tiles aren't calculated based on a memory size, but on a pixel size. Odd shaped (ie, non-square) render targets will create odd shaped tiles, and the last tile may be larger than needed to account for that. For example, if you have a 1280x720 surface and 3 tiles used in that, you can be assured that you don't have 3 separate tiles each of size 426.67x720. Each tile is rounded up to the next size it can be (normally a mutliple of 32). In the case above, that 1280x720 surface would really be three tiles of size 448x720 with the third title having some "empty" space in it. So if you do your little math above and it comes to exactly 15 tiles, you still may be too big if the tiles aren't the size you'd expect.

Do I really expect someone to try to create and use four simultaneous 2048x2048 Color render targets with 4x multisampling and a 32bit depth buffer? Well no, because as you've seen here, it would fail! However, if it does fail, at least this hopefully explains why!

By the way, in reference to my fake first question. You can actually do this just fine, so long as you aren't using 4x multisampling, and even with 4x multisampling, it just barely doesn't fit with a depth buffer (1900x1080x16bytes == 31.3 MB / 2MB == 15.6 tiles). Four 2x multisampled render targets at 1080p would fit though.

Why CornflowerBlue?

tmiller — Thu, 28 Feb 2008 02:55:00 GMT

This post will be purely speculation by me!

Take a time travel machine back in time to early 2003. It might have even been late 2002, but I think it was 2003. I was coming up with the concepts and code that would eventually be my first kick start book, and was rendering everything on a bland black background. For some things, black makes sense, but it's hard to see shaded objects (and particular shadows, etc) on black objects. Black in general is a horrible color to use as a clear color. If you clear your scene to black, then render a model and see nothing but black, what went wrong? Was the model not drawn because your camera is facing the wrong way? Was the model drawn, but not colored because your pixel shader wasn't set? You could tell the difference if your background wasn't black.

I needed something brighter, and white was out of the question. I can stare at a white screen all day as I type text, but a white background with a single 3D object on it is just too contrasting and is ugly in my opinion. So i needed a color that was light, but not too light, dark, but not too dark, and it needed to be something that I would feel comfortable using for just about anything.

So, as I was inside visual studio, I typed "System.Drawing.Color" then hit the extra period and started scrolling through intellisense, stopping at ones that sounded promising and trying them out. I eventually narrowed it down to a light shade of blue. I had narrowed my choice down to "LightBlue" "DodgerBlue" "PowderedBlue" "RoyalBlue" and "CornflowerBlue". For various reasons I eliminated a couple more and came down to a list of three left.

I had to choose between CornflowerBlue, RoyalBlue, and DodgerBlue. I tried various models on each of the background colors, and finally decided that RoyalBlue and DodgerBlue were too "bold" and contrasted too much, but CornflowerBlue was a much more "calm" color, and everything I tried looked good against it. Plus who wants to use a color called "RoyalBlue" or "DodgerBlue" when "CornflowerBlue" is such a cooler name.

If you've read my Kickstart book, the vast majority of sample code in there clears all of the backgrounds to CornflowerBlue. Every sample I've written since that point in time does as well.

Can I say with any sense of certainty that everyone else uses it because I did way back then? Probably not, I'm sure there are people who haven't even read that book! At times though, I like to delude myself and think I started the craze way back then. =)

Why purple?

tmiller — Fri, 22 Feb 2008 06:00:00 GMT

One of the things I'm going to try to do this year is write more on my blog. The publisher for my books is hoping I'll write something new for them this year as well, although at the moment I don't know if I'd have the time, or what I'd write about anyway.. Anyone have suggestions on topics they'd like me to cover in a book or a blog post? Shawn normally goes a great job staying ahead of the curve so the possibilties of topics diminishes some. =)

So for now I'm just going to post a random anecdote that was asked in our internal alias one day.. Why does the framework clear the targets (render targets, back buffer) to purple when RenderTargetUsage.DiscardContents is turned on?

When I originally implemented that feature, I wanted something that jumped out at me and was extremely noticeable. I picked the brightest, most obnoxious shade of neon green I could. It did the trick, it was instantly noticeable when it was there. As time went on though, I kept seeing it all the time, day in, day out, over and over again. It irritated me something fierce and eventually I decided I just had to change it to something much less obnoxious, so I picked a dark purple. The intention was to switch it back to the bright neon green before we shipped to ensure everyone got to experience the joy that was that color.

As time went on though, we all got used to the purple. It was pretty quickly and easily recognized and that was the goal for the clear to begin with. Why torture everyone's eyes and have them all hate me when everyone is soothed by the purple?

So, why purple? To avoid the hate mail that would have come from the original neon green!

XNA Game Studio Express Update

tmiller — Fri, 09 Mar 2007 00:24:00 GMT

Next month we'll be releasing an update with a small sampling of some of things we've been working on. You can read more about it on our team blog here.

GDC? Books? A web site? A blog post?

tmiller — Tue, 06 Mar 2007 01:23:00 GMT

I never seem to find time to write posts here anymore. Well, to be more accurate, I get frustrated with the number of things I get as direct responses to posts (or even just random mails from people from this blog). Honestly the top two questions I get are people wanting me to send them copies of my books and people asking me for help with their homework. These are normally followed up shortly by those same people letting me know how much of a jerk I am for not relenting to their request. It doesn't seem to matter if I ignore it or respond politely, the same result occurs either way. It's almost enough to make me wonder why I even write anything (and I'm fully convinced it will be worse at least for a short time after this post).

Anyway, enough random complaints from me, and onto what I originally was going to write about..

After the two topics above, the next most asked about topic is about books. When is my next book coming out, when am I updating one of my older books, etc. So let me ask you what you'd like. If I were to write a third book, what would you like to see? I'm guessing not many people will suggest science fiction or an in depth discussion of the civil war.

If you haven't heard recently (sometimes I am a little slow on the announcements) we have launched a new creators club web site. It has a new starter kit for you to download and enjoy, a number of samples to look at, and even new forums. Naturally, there is more there as well, so go check it out!

We also have our Dream. Build. Play. contest going on, and we announced some of the prizes which are simply amazing in my opinion ($10,000 cash, a new computer, a chance to have your game published on Xbox Live Arcade and more?). There was also a 'warm up' contest using the Spacewars starter kit that had some amazing entries. I'm excited to see the things that will come out of the real contest now. Like I've mentioned before, I've always wanted to run a contest for something like this.

As part of the GDC list of announcements, we also have a lot of great information. Such as Creators Club members getting a license to the Torque X engine. None of this even hints at some of the things we are hoping to have done in the not too distant future. For anyone who thought we were going to be resting on our laurels as they say, rest assured we are doing nothing of the sort.

Now if I could just get myself to be more like Shawn and actually write some technical posts here once in a while...

Reflection

tmiller — Tue, 02 Jan 2007 10:35:00 GMT

With a title like that I’m bound to start discussing the intricacies of one of the CLR features am I not? Well given the day, I have to say of course not. I’m going to take this time to remind myself of the things that have happened over the last year.

Have you heard? We shipped the Xna Game Studio Express! Honestly, I thought I had written a short post stating that, but apparently I’m losing my memory in my old age, because it certainly doesn’t appear to be here! For that, I apologize, but it wasn’t a secret that it was coming out, so hopefully this isn’t a surprise to anyone!

As I insinuated in a post a few months ago, this release has been quite ‘special’ for me.

This time a year ago I was still in the DirectX team. Such a thing as “Xna Game Studio Express” didn’t exist, and the amount of people even aware such a thing was being considered was very small. This team has gone from essentially nothing to having a product out that will changes the rules in this industry. This was all done in the space of a single year’s time (really in just a few short months). This is an absolutely remarkable achievement, and I hope every single person who helped make this possible feels the same sense of pride that I do. The hard work shown by this team and how we pulled everything together to allow all of our anxious customers to start using Xna was a sight to behold.

When I see things such as Xna Racer and various other games being created in the community that prove all the people who were telling me how impossible it would be to create such things using managed code, it makes all the long hours I’ve put in over these years to help make this happen worth it.

It’s not often in life you get to be a part of something that not only can change the industry you work in, but can spawn an entirely new one as well. What this team has accomplished in such a short time speaks volumes about the passion and dedication they have and bodes well for the future of this product.

We’ve accomplished all my original goals for managed code in gaming. We’ve released a product with plenty of support. We’ve opened up the Xbox 360 for development using managed code. We even have a contest going for you to enter to win great prizes. I’ve been trying to set up a contest for a very long time.

Knowing some of the features we have planned, and seeing what the community already has done in such a short time, I couldn’t be more proud of where we’ve ended up. The excitement is just beginning. The rest is up to you!

Managed Games? Of course!

tmiller — Fri, 01 Sep 2006 22:28:00 GMT

You may remember me talking about Koios Works before. They wrote one of the first retail games using Managed DirectX. They have an entirely new 3D game out now called Panzer Command: Operation Winterstorm

Not only are they still using Managed DirectX and having a full 3d game going, they won first prize in a contest sponsored by Intel with a nice chunk of change reward!

I wonder if and when they'll be moving over the Xna Game Studio Express? =)

Download the Xna Game Studio Express (Beta) now..

tmiller — Wed, 30 Aug 2006 18:17:00 GMT

Just click this link.

Beta?

tmiller — Tue, 29 Aug 2006 21:26:00 GMT

I heard somewhere that we might be having a beta of the Xna Game Studio Express before the end of the month.. And the end of the month is almost here!

I bet you could sign up here for it right now!

Random XNA thoughts and links..

tmiller — Sat, 26 Aug 2006 01:50:00 GMT

Well, maybe not so random.

First, ever wonder what the XNA Framework was? Look at Mitch's latest post on the Xna Team Blog..

Second, a coworker has recently started a blog, and he has a number of interesting posts, including explaining why he joined the Xna team.

Which makes me get quite nostalgic myself. Shortly after we announced I sent out an email internally, which i'll now include here (albeit slightly modified for the public)..

---- Insert Sentimental Thoughts.

I can't decide if it seems like yesterday or a lifetime ago, but GDC in 2002 was the first public showing of what became known as Managed DirectX. Since that date I've listened to countless people telling me how and why managed code could never be a viable game development platform. Actually, I guess that's a lie. It started before then since it was an uphill battle in the DirectX team just to get it to ship in the first place.

Yet here we are today, and listen to the buzz. It was almost instantaneous. Gone are the cries of impossible, replaced with the excitement of "when can I get it" and "omg, are you serious?" Just wait until later this year when they're actually using it. I can't wait.

I'm sure everyone gets up and comes to work for their own personal reasons, and I doubt everyone shares mine, but what gets me going (and keeps me going) is a combination of two things. One, the ability to make a difference, and I'd be lying if I didn't say there was a certain egotistical aspect as well.

Not only am I no longer alone, there's an entire team focusing on much larger issues, bringing an entire end to end solution. This team is fulfilling not only my original goal with Managed DirectX -- opening up game development; but going so far beyond what I had hoped it's hard to describe. It's been a long time since I've been so excited about a project, and it's a feeling I've missed. Not only do we have the "egotistical" aspects intact, but we have the opportunity to change an entire industry for the better. If that isn't making a difference, I'm not sure what is.

Truth be told, this is probably one of the most sincerely "proudest" moments I've been able to achieve in my career, although I'm sure it will be surpassed later this year when we've actually shipped and people are using our stuff. We're not only pushing people towards the next age of game development, we're defining what that means. I couldn't be more excited.

Have you seen the XNA Team Blog?

tmiller — Tue, 15 Aug 2006 04:20:00 GMT

In one of my posts yesterday I linked to it, but it is a good blog to read. I really enjoyed the little bit of extra information from Boyd in today's post.