Book Review: Seveneves by Neal Stephenson

In my (humble) opinion, when it comes to intellectually stimulating and hardcore cyberpunk science fiction, there is no better author than Neal Stephenson, who does a great job in each and every one of his novels to date. For anyone who likes vast concepts steeped in technical, scientific, philosophical, and mathematical landscapes, portrayed in even more vast settings within (science) fiction, Neal Stephenson presents just that, taking your brain on an intellectual roller coaster ride each time you read one of his books. The very first book I read was Cryptonomicon, (a copy which belonged to my uncle) and it blew my mind. I also went on to read two more of his novels, Anathem, and Reamde, which showcased the ability of the author to create unimaginably different worlds and settings from book to book. For instance, Anathem is speculative fiction featured in a monastic setting (with a theme revolving around the many worlds interpretation of quantum mechanics) which has deep philosophical implications, whereas Reamde is a fast paced techno thriller revolving around a MMORPG with crypto-currencies, social networking, and hacker culture thrown into the mix.

Coming back to why I wrote this post, Seveneves is a novel by Neal Stephenson published in 2015, which was also recommended by Bill Gates who says it is the first science fiction book he has read in a decade. It is a work of speculative fiction, and starts off with a major catastrophe brought on by the destruction of the moon, that triggers a series of apocalyptic events. The story spans from the time this event takes place, to thousands of years in the future, which in itself, requires the reader to digest a vast time range of activities pertaining to the human will for survival. Personally for me, it is a book with an interesting premise that evokes a lot of thought and insight.

My advice on reading books by Neal Stephenson: pick a book that has a theme interesting to you, and see if you like his style and presentation (You might learn a lot about Mathematics, Cryptography, The Enigma machine, Van Eck phreaking, UNIX, and the history of world war two just by reading one book, which is what happened when I finished reading Cryptonomicon).

Installing MINIX 3 on QEMU/KVM with networking

For quite some time I’ve been wanting to play around with the source code of MINIX, partly because I like to understand how operating systems, well, operate, and partly because I am a firm believer in the design philosophy of a modular micro-kernel OS architecture (vs the traditional monolithic approach) and wanted to see how one was implemented. I was trying to set up a MINIX installation on VirtualBox but could not get the networking to function properly inside of my MINIX guest OS which I needed. This post is basically a detailed (b)log (expanding on the MINIX guideline) of how I switched to QEMU/KVM and got a working MINIX 3 installation complete with networking, to experiment with (when I mention “networking”, I am referring to accessing the Internet from the MINIX guest OS).

First off, I need to mention my host OS is Ubuntu 16.04 (32bit) running on a core 2 duo machine with 1GB of RAM. I also enabled the virtualization extensions in my BIOS (required by KVM, else there will be an error during the MINIX installation), which is quite trivial to configure in your machines.

A word about QEMU and KVM: QEMU (short for Quick Emulator) is an open source machine and peripheral emulator, focusing primarily on portability. KVM (Kernel based virtual machine) was originally a fork of QEMU, is a Linux kernel module that handles virtualization, and is now part of the main Linux source by default. To make a long story short, QEMU is a stand alone software, but will use KVM if it is available. There are many online resources on these two technologies which can be referred for a further understanding of emulation vs virtualization.

In order to install QEMU in Ubuntu, we need to type the following in the terminal:

sudo apt-get install qemu qemu-kvm libvirt-bin

Once this has run, QEMU will be installed in your host system.

Next, we will create a folder which will hold our QEMU VM image. In my system, I created a folder named “qemuVMs” in my Home folder. Also, we need need the MINIX 3 ISO file that will be used to install the MINIX system, which can be downloaded from the MINIX download page. At the time of this writing there were two versions available for download, and I selected version 3.3.0. Once the file is downloaded, you can extract the contents to get the ISO file, which needs to be copied into the folder we created earlier (in my case /Home/qemuVMs/).

Once the ISO file is in our folder, we can fire up a terminal, navigate to the folder containing the MINIX ISO file, and type the following command to create the VM image:
qemu-img create minix.img 2G
The above command will create a VM image named ‘minix’ with 2Gb space to hold our MINIX system (you can change the image name and size as you see fit). Now the contents in the folder should be something like the following:

Screenshot from 2016-06-11 22-33-52

Once the VM image is ready, we can boot the ISO file by running the following command at the terminal:

qemu-system-x86_64 -localtime -net user -net nic -m 128 -cdrom minix_R3.3.0-588a35b.iso -hda minix.img -boot d

This command basically tells QEMU to use the minix_R3.3.0-588a35b.iso file in the minix.img VM, and to allocate 128Mb of RAM for the VM. Please note to replace minix_R3.3.0-588a35b.iso with the name of the ISO file you downloaded, when running the above command.

If everything goes as planned, you should be taken through the normal MINIX 3 installation routine, which you can follow based on the guidelines given in the MINIX site. There are two important points to note during the MINIX setup:

1. When the option to select a network interface is given, select the “Virtio network device” option.
2. When asked whether to configure network using DHCP or manually, select “Automatically using DHCP”.

(We can always change the above network configuration in MINIX by typing “netconf” at the MINIX command prompt, but setting them during the initial setup will save us a step when we reboot into the new system)

Once MINIX 3 is installed in the VM, we need to change some configurations in the newly installed MINIX system, in order to utilize the virtualized disk and network drives and have internet access from the MINIX system. So boot into the new MINIX system by typing the following at the (Host OS) terminal:

qemu-system-x86_64 -rtc base=utc -net user -net nic -m 128 -hda minix.img

Once we are logged into the MINIX system, we need to go up one directory from the default file location, and navigate into the etc/ folder to modify the boot.cfg.default file. The following image shows how I have navigated from the point I was logged into the MINIX system till where I am going to edit the configuration file using the (ported) vi editor already available in the MINIX system:

Screenshot from 2016-06-11 23-11-07

When I open the file with vi, I need to add a new menu line with the following contents:
menu=Start MINIX 3 latest serial virtio:load_mods /boot/minix_latest/mod*;multiboot /boot/minix_latest/kernel rootdevname=$rootdevname $args cttyline=0 virtio_blk=yes

(basic editing commands in vi can be found in numerous sites online. Generally you will type shift + i to edit text, escape key to finish the edits, then shift + ‘:’ to get the vi prompt, and type “wq” at the vi prompt to write changes to disk and exit the editor)

You can see the last three lines in below screenshot, where I have added this new line of text in the boot.cfg.default file:

Screenshot from 2016-06-11 23-20-13

Once the above changes are done, we can exit the editor. We are still in the /etc/ folder, so we need to go back up one step in the file hierarchy, and then navigate into the /bin folder for the next step. Inside the /bin folder, we just need to run the update_bootcfg (just type “update_bootcfg” at the MINIX command prompt and press enter) command to make the changes we did in the boot configuration file come into effect. The below screenshot shows this (from the point we exit the vi editor):

Screenshot from 2016-06-11 23-29-49

After the step above is completed, we can shutdown the system by typing “poweroff” at the MINIX prompt, and reboot into the system using the following new command:

kvm -net nic,model=virtio -net user -drive file=minix.img,if=virtio -serial stdio -m 128

(It would be easy to have this command in a shell script so that we do not need to type it each time we need to fire up the MINIX guest OS)

Now when you boot into the MINIX guest OS, you should see a new option named “Start MINIX 3 Latest serial virtio” which is what we configured in the boot configuration file earlier (option 6 in below image):

Screenshot from 2016-06-11 23-37-24

If we select this boot option and login to the system, you would find that we have full access to the internet via the virtual network interface we have configured. If you do a “pkgin update” at the MINIX prompt, you should be able to see MINIX retrieving package details over the internet and updating the package database.

If you run into any issues when installing MINIX 3 (with networking) in QEMU following the steps outlined above, please do leave a comment.The MINIX3 Google group is also a great place to check for common issues and support, and a better forum to put your discussions/problems forward, as it will benefit the whole MINIX community.

Using the DirectX SDK in Windows 8 with Visual C++ 2010

This post is a result of some insight and necessary steps to get the June 2010 DirectX SDK working on a Windows 8 system, with Visual C++ 2010 express. Given the fact that DirectX 11 comes bundled in with the Windows 8 SDK, my stubbornness to change the configuration is due to the fact that I wanted to follow Frank D. Luna’s latest book, mirroring the same development environment (Visual Studio 2010 and the DirectX SDK) in my Windows 8 machine. Without further ado, lets dive in to the details…

  • Windows 8 comes with DirectX bundled in – The Windows 8 SDK comes with the DirectX SDK bundled in, and in turn, Visual Studio 2012 comes with the Windows 8 SDK. This means, you can download VS 2012, and start writing DirectX code without any further configuration. Microsoft recommends (Specifically in this blog), that developers transition to coding DirectX application using the new Windows 8 SDK and VS2012. If you are planning to go down this route, just install VS 2012 Express for Desktop on your Window 8 machine, and try out these great tutorials.
  • Windows 8 Contains DirectX 11.1 – What you will not be able to get from the DirectX SDK are the new features available in DirectX 11.1. This does not pose much of a problem, as much of the DirectX code out there is based on the DirectX SDK, and DirectX 11.1 features have not been widely adopted yet. If you are interested in the new DirectX 11.1 features, head over to this page and check them out. But bear in mind that you need to develop using the Windows 8 SDK if you are planning to use it (The windows 8 SDK is available as a separate download if you want to develop in Windows 7 for example).

If you are like me and want to use Visual C++ 2010 and the June 2010 DirectX SDK in Windows 8, then the below steps outline what needs to be done (I am assuming you are using a Windows 8 machine):

  • Install Visual C++ 2010 Express Edition – Navigate to the download page for VC++ 2010 express and install the product on your Windows 8 machine. (On Windows 8, after installation, there were some problems where the product did not fire up, stating that I needed to install the service pack for all VS2010 products in my system. When downloading and installing the service pack, some errors were thrown as well. But after restarting the machine and firing up VC++ 2010 Express, it worked properly… am still investigating why all this fuss. This seems to happen if you have other VS2010 express edition products installed already).
  • Install the DirectX SDK on your machineGo to the DirectX SDK download page, download the SDK and install in your system. One thing to note when installing in Windows 8, you will get installation errors if there are existing 32-bit and 64-bit VC++ 2010 redistributables installed in your system (This is because the DirectX SDK uses an older version of them). Follow the steps outlined in this page, in order to get the DirectX SDK installed properly on your Windows 8 system.

If everything went well, you should be up and running in coding and building DirectX applications using VC++ 2010 (provided that you link the appropriate libraries and set the folder paths in the project settings) on your Windows 8 system.

Infragistics UltraWebGrid column format not being applied

Just a short post today, recalling an incident I came across recently, which I thought I should jot down here, and hopefully It’ll save someone else a headache.

If you have been working with the 3rd party UltraWebGrid control for asp.net offered by Infragistics, you would have worked with columns where you might have wanted to display numerical values formatted in a certain way (for example, you may want to show 12, 300, 450.0 instead of 12300450.0000). This is done by setting the format expression in the column.Format property inside the ‘InitializeLayout()’ UltraWebGrid method. This is exactly what I was doing but was puzzled to have rows of integers merged from two DataTable sources showing different formats, even though each Integer in the rows were applied the same column.Format expression in code. The first few integers would display in the correct format I apply, but sometimes the last few integers don’t have the formatting applied.

This was getting way too frustrating till I (out of curiosity, and nothing else to try) wrote the following line of code before the ‘column.Format’ expression:

string dType = column.DataType;

When I debugged the code, one set of integers from the original DataTable was of type ‘System.Decimal’, and displayed correctly, but the second set of merged integers from the second DataTable was of type ‘System.String’. When I set the following line of code inside the loop applying the formatting to the column.Format property, all the integers displayed in the correct format:

column.DataType = “System.Decimal”;

So bottom line? The UltraWebGrid control cannot format columns with decimal format expressions if even one value in the column is going to be of a type other than ‘System.Decimal’. If there are several columns which will display numerical data in a certain format that you need, it would be defensive coding to write the logic in UltraWebGrid_InitializeLayout() as follows:

foreach (<column in UltraWebGrid that is going to display numeric values>) {

column.DataType = “System.Decimal”;

column.Format = <your numeric format expression here>;

}

3D GAME MATH PRIMER 4: OPERATIONS ON VECTORS

In a 3D game environment, vectors are used to hold the values of points or vertices. Thus a vector would contain a coordinate [x, y, z] which represents the specific vertex in 3D space. Points are defined such by vectors because the start position of the vector is usually taken as [0, 0, 0] which is the origin of the coordinate space. Thus all the vertices in 3D models and game elements are represented by vectors, but it is important to remember that vectors are not 3D vertices. (There is another type of vector that is represented by 4 coordinates [x, y, z, w], which are homogenous coordinates. We will talk about this in a later post dedicated solely to this very important and interesting topic).

Another place where vectors are used are  surface normals. Every 3D surface has a surface normal, which is nothing but a vector pointing away from the surface and perpendicular to that surface. This vector (surface normal) determines how light sources in the environment light up the specific surface. This is just one aspect of the surface normal, as it is used in many other places in the game. Vectors are also used in shading (which we will talk about later), and dynamically processing visual elements in the game.

Simply put, vectors are one of the most used constructs in 3D games. This is why learning and understanding about vectors and their operations is very important. Without further ado, lets dive in to learn about vector operations and some basic linear algebra.

THE ZERO VECTOR

The zero vector is the additive identity in the set of vectors. The 3D zero vector would be denoted by [0, 0, 0]. This vector is a special vector because it is the only vector with no magnitude or direction. It would be easy to assume the zero vector as a point, but the reader should remember that a point represents a location. It is better to remember the zero vector as a vector with zero displacement.

VECTOR NEGATION

Vectors negation can be related to multiplication of scalar numbers by -1. The negated vector is known as the additive inverse of the original vector. A vector of any dimension is negated by all its individual components as shown below:

– [x, y] = [-x, -y]

-[x, y, z] = [-x, -y, -z]

Geometrically speaking, vector negation produces a vector same as the original, but with opposite direction.

MAGNITUDE OF A VECTOR

Vectors have a magnitude (length) which can be calculated simply by taking the root of the sum of squares of the individual dimensions. This is very simple if you remember the very basic skill of calculating the length of the hypotenuse in a right angled triangle using the Pythagorean theorem (for 2 dimensions).

For a 2D and 3D vector, the magnitudes are defined as below, respectively:

2D3D

VECTOR MULTIPLICATION AND DIVISION BY A SCALAR

Vectors can be multiplied by scalars, and this happens by multiplying the individual components of the vector by the scalar value. What we geometrically obtain by scalar multiplication is another vector that is parallel to the original vector, but which could differ by magnitude or direction, depending on the scalar value. Some examples are given below:

k[x, y, z] = [kx, ky, kz], -2[4, 0, 1] = [-8, 0, -2]

Vectors can be divided by scalars as well, and this would be equivalent to multiplying the vector with the reciprocal of the scalar value, which is shown as follows:

1/k[x, y, z] = [x/k, y/k, z/k]

Some important aspects to note:

  • We do not use the multiplication sign in scalar-vector multiplication, nor the division sign.
  • Multiplication and division take precedence over addition and subtraction.
  • Vector negation is a special case of scalar multiplication, where the scalar value is always -1.
  • The geometric interpretation of scalar – vector multiplication is the scaling of the vector by a magnitude of |k|, the scalar value.

VECTOR NORMALIZATION

In many situations, it is not the magnitude of the vector that is important, but the direction. In these cases it is convenient to work with unit vectors, which have the same direction of the original vectors, but their magnitude is 1. The process of taking a vector, and converting it into a vector of magnitude 1 while maintaining the direction, is known as vector normalization. The unit vector is known as the normal.

A vector is normalized by dividing the vector by its magnitude (scalar division, as the magnitude value is a scalar). The result is a vector which is the normal to the given original vector:

Vnorm = V/||V||, Where V is not zero.

The below image (courtesy of the book 3D math primer for graphics and games development, by F.Dunn and I.Parberry) show unit vectors in 2D space, which touch the surface of a circle of unit radius. In 3D space, unit vectors would touch the surface of a sphere of unit radius:

unitVectors

VECTOR ADDITION AND SUBTRACTION

Vectors can be added or subtracted only when their dimensions are equal. The individual components of the vectors are added or subtracted to obtain the resultant vector. Though vector addition is commutative, vector subtraction is not. Examples of vector addition and subtraction is given below:

[2, 5, -1] + [3, 1, 0] = [5, 6, -1]

[3, 0, -3] – [5, -2, 0] = [-2, 2, -3]

The geometrical concept of vector addition and subtraction is the basic triangle rule. Given the vector addition of two vectors A and B as A+B, we need to find the resultant vector which has the starting position of A, but the ending position of B. This can be applied to many vectors. Vector addition may seem a simple enough concept, but we will later see a similar mechanism to transform vectors from one coordinate space to another.

In the next post, we will continue the rest of the vector operations, and look at two very important operations: Vector dot product and the vector cross product.