Vista Service Pack Installation Problems

I recently installed Windows Vista SP2, and like Vista SP1, I seemed to have problems getting it installed properly. It would spend a huge amount of time installing itself, reboot, and then fail during its third stage, and then spend a lot of time reverting the install. Windows Update would show Code 80004005 in the error details field for why the update failed.

Fortunately, after browsing the web, I found a forum post (I no longer remember where it is), where people mentioned that the problem comes up with dual-boot machines. My machine has both Linux and Windows installed, and Vista apparently fails its TPM security checks or something like that if the GRUB boot manager starts up in-between the computer starting and Vista starting. Fortunately, I installed GRUB on my Linux partition instead of my MBR, so I could simply change my active/boot partition to boot directly into Windows. Afterwards, the service pack could apply itself, and then I could boot on a Linux live CD to reset the active/boot partition back to the Linux partition.

Personally, I find this sort of annoying. It would be nice if Windows wouldn't die on dual-boot machines or give users a prompt to allow then to ignore TPM problems during the boot process or, at the very least, give more useful error messages.

MTU Problems When Using Vista Internet Connection Sharing (ICS) with an XBox 360

So like other people, I don't really like the idea of paying $100 for an XBox 360 wifi adapter, so I'm using Internet Connection Sharing through my laptop to get my XBox connected to a wireless access point (yes, there are easier ways of doing this, but like usual, I'm doing something strange).

But when I did this, the XBox kept complaining that my MTU was set too low since it needed an MTU of 1364. This is a little silly since a proper IP stack should automatically fragment its packets to accomodate the MTU, but whatever.

I ran the command netsh interface ipv4 show interfaces to find out what the MTUs on my Vista laptop were, and they were all set to 1300. This seemed a little strange because 1300 is oddly low and also a nice round number that a human must have decided on. But I certainly hadn't set my MTU to 1300, so I'm not sure why it was set to that.

I spent a while browsing around, but finally I figured it out. It was that annoying Cisco VPN client on my laptop. I have no idea why they set the MTU so low (what sort of intermediate router would use 200 bytes of overhead per packet? It's silly to reserve so much), but the VPN Client comes with a Set MTU program that I was able to use to set everything back to normal, and then my XBox stopped complaining.

Running TPC-H Queries on MySQL

Getting the TPC-H queries to work on MySQL isn't too hard, but it isn't always clear what to do. I took the instructions from here and converted them to work with MySQL.

Once TPC-H is started, you can create a database and tpch account:

mysql -u root -p
mysql> CREATE USER 'tpch'@'%' IDENTIFIED BY 'password';
mysql> CREATE DATABASE tpch;
mysql> GRANT ALL ON tpch.* to 'tpch'@'%';
mysql> USE tpch;
mysql> \. tpch/gen/dss.ddl

Then, in the gen directories, you can modify the query generator to generate queries that are as close as possible to what you need:

cp makefile.suite makefile
#Modify makefile to use
# CC = gcc, DATABASE=SQLSERVER, MACHINE=LINUX, WORKLOAD=TPCH
#In tpcd.h, SQLSERVER section:
# change #define SET_DBASE "use %s;\n"
# change #define SET_ROWCOUNT "limit %d;\n\n"
# change #define START_TRAN "BEGIN WORK;"
# change #define END_TRAN "COMMIT WORK;"
make

Then you can start generating database data at the right scale factor

./dbgen -s 1

And also modify the constraints/indices file so that it's compatible with mysql:

# Modify dss.ri
# use a search and replace in order to remove "CONNECT TO TPCD", remove references to "TPCD." and remove the lines "COMMIT WORK;"

Then you can load all the data into the databases with

mysql -u tpch -p
mysql> use tpch;
mysql> LOAD DATA LOCAL INFILE 'customer.tbl' INTO TABLE CUSTOMER FIELDS TERMINATED BY '|';
# Same with orders, lineitem, nation, partsupp, part, region, supplier
mysql> \. dss.ri

You then need to change the case of the table names because the queries use lower-case table names I think whereas the dss.ddl uses upper-case names for the tables:

mysql> alter table NATION rename nation;
# Ditto for supplier, region, partsupp, part, orders, lineitem, customer

Finally, you can test some of the queries

cp dists.dss queries
cd queries
../qgen -c tpch -s 1 1

I think the queries still need to be modified a bit to be compatible. I think queries with a limit may need the semi-colon moved around, the precision indicator during date arithmetic in query 1 may need to be removed, and the method for naming columns in query 13 might need changing.

Chinese Handwriting Recognition in Windows XP

If you want to write Chinese characters in Windows XP, there are lots of options available like Google's IME, but a lot of these options aren't practical if you don't know any Mandarin. There are websites for inputting Chinese in Cantonese, but still it isn't ideal.

Apparently, the IME in Windows XP can be upgraded to support limited hand-writing recognition in Chinese, but Microsoft conveniently hides the IME upgrades on its websites. Fortunately, I found a forum, which describes how to download these upgrades from the MS Office website. Once I installed these upgrades, I could then use the IMEPad to write Chinese characters using a mouse or tablet. In fact, the IMEPad option was available in my plain version of Windows XP, but clicking on the IMEPad button did not result in anything happening.

IE7 Erases .XML Files

So I had spent a few days writing a long .xml file with a corresponding .xsl stylesheet. I was using IE7 to look at the generated html. At one point, I chose Page, then Save As. Then I chose Cancel.

Poof.

IE7 erased my .xml document. Well, I guess I didn't really need the document that badly after all.

Tiles Don't Generalize

For a couple months, I've been experimenting a bit with SVG during my free time to get a feel for how to use it cleanly on the web. In particular, I've been playing around with trying to create a little tile-based game using SVG and JavaScript.

The nice properties of grid-based tiles using an isometric or 3/4 perspective are well-known. As long as every object in the game fits exactly in a 1x1 grid cell, then everything works great. It's easy to figure out an order to draw the objects in order to ensure that nearer objects properly occlude further objects. You can stack objects within a grid and do other nice stuff too.

After seeing all those isometric-perspective computer games with characters running in-between grid tiles and with all manner of odd-shaped objects though, I assumed that the algorithms for choosing the order to draw objects in the isometric perspective generalized in some nice way. Of course, I realized that things couldn't generalize arbitrarily. If you allowed for arbitrary objects in arbitrary poses, then you'd end up with an arbitrary 3d scene drawn from an orthographic perspective. Then you'd need the full painter's algorithm with polygon chopping etc.

But, I assumed that if all objects were in non-overlapping axis-aligned bounding boxes, then I could figure out some way to order the objects without needing to chop any of them (since you can't really do this is SVG). In particular, I wanted the floor tiles and the objects to be all mixed up in the rendering code. But for the isometric perspective, it is possible to create degenerate examples where objects mutually occlude each other. So you can't generalize algorithms for the isometric perspective this way. In particular, my plan of having floor tiles and wall tiles, plus arbitrarily sized objects sitting on the floor tiles just wouldn't work.

In fact, the same thing happens with the three-quarter perspective as well (I've shifted the perspective a bit so that it's easier to see the depth of the objects).

So having arbitrarily sized objects that can stack on top of each other arbitrarily won't work. Having objects in non-overlapping axis-aligned bounding boxes where all the bounding boxes sit on the same plane, that seems to work ok. With the isometric perspective, it seems like it might be a little bit hard to get the right ordering of objects during drawing, but it seems doable at least. With the 3/4 perspective, everything works out well in that particular situation.

So basically, one way to get around this problem is to have a flat floor and use tiles to cover the floor as one layer, then on a second layer, you can have objects and walls and stuff that you can order separately. I imagine there are other cases that lead to an easy ordering of objects (perhaps if everything has a fixed height? or maybe in the 3/4 perspective, if you allow for only two levels: one for arbitrary height terrain and then another for things on top?), but I haven't really figured it out yet. Perhaps in reality, degenerate cases never really end up occuring, so you can just sort of hack in lots of special cases in the rendering engine to make sure all the objects are rendered in the right order.

Well, in any case, the point of this post is to show that tiles are trickier than I thought. They really don't generalize nicely, so you have to put a lot of thought into how to handle things once you allow for objects that don't fall exactly within grid boundaries.

Resolution Independence in Vista

I recently got a Thinkpad notebook that crams a 1400x1050 resolution onto a tiny screen. It's a great screen, but unfortunately everything ends up being a bit too small. If you have resolution independent applications, the increased resolution can be a real joy though because the text becomes so clear and easy on the eyes. Although previous versions of Windows had very limited support for resolution independence, things supposedly had improved quite a bit in Vista.

Unfortunately, things don't quite fit together that well. Just like earlier versions of Windows, you can increase the default font size in Vista. Unfortunately, this causes various glitches in things. For example, text no longer fits in the dialog boxes of Windows Media Player (I suspect that the Windows Media Player people must have written some custom dialog box code because I'm pretty sure the default dialog box code scaled things correctly even back during the Windows 95 days). And lots of fonts on web pages are specified in terms of pixel sizes, and their sizes don't get adjusted, so the text ends up being too small to see. Internet Explorer does have a zoom capability that redefines pixel sizes, but it also increases the size of the default font, which has already been increased, making things look too big.

Vista also has the option of simply scaling up all pixels to a larger size. Basically, Windows will fool legacy applications into thinking that the screen has a lower resolution, so that the applications render at a smaller size. This render is then scaled up to fill the larger resolution. Resolution independent applications, however, can render at the full resolution. Unfortunately, Adobe (Acrobat) Reader is considered a legacy application. Being able to read .pdf documents with crisper text is one of the main reasons I chose the high resolution screen, and you lose all those benefits if you render everything to a lower resolution and then scale it up. I imagine the same problem crops up in other applications as well. For example, Internet Explorer doesn't have strong support for vector drawing formats like SVG, so it's not possible to get high resolution graphics on web pages, so you have to live with scaled up versions of bitmaps instead.

Based on this experience, I imagine it will take another few years before it becomes practical to use Windows comfortably on a high resolution display. The new version of MacOS will supposedly have strong support for resolution independence, but I doubt that they've actually managed to solve the problem in a comprehensive manner. I think that doing resolution indepence right probably requires a larger rethinking of UI widgets and layout managers (basically, it will be the same technology needed to layout a single UI design on both tiny mobile device screens and large LCD monitors with needing lots of manual tweaking), but I haven't really heard much about research into that area by Apple, so I doubt they've hit the final solution yet.