Sam Murphy

Creating A Heightmap With Particle Deposition

2016-09-26T00:00:00+00:00

After completing a third year project on procedural terrain generation, I decided to look in to some of the other algorithms for generating height maps. One of the more interesting methods I came across was called Particle Deposition, I found out about it in the book Game Programming Gems (which I highly recommend). The book briefly describes the technique, but provides no code and I’ve been unable to find much information on it any where else; so I’ve put together this post to provide others who might be researching the topic.

The general purpose of the algorithm is to create height map by dropping particles onto a plane, the clever part is that once the particle lands it is tested for stability and moved slightly into a position where it settles. The overall effect of this is creating volcanic style islands.

The Algorithm

To start with you need to define a number of droppers, and a number of particles for each dropper. A dropper in this instance is just a starting point somewhere on the grid, that we’ll drop the particles onto. Once you have these defined, you just loop through the number of particles for each dropper moving the dropper every time you place a particle.

foreach dropper
{
	x = random(0, Width);
	y = random(0, Height);
	
	foreach particle
	{
		Check stability at x,y
		Place particle
		Increment x or y to move dropping point		
	}
}

Running Shell Commands with Php and Apache

2016-07-29T00:00:00+00:00

My internet connection for my home server is slightly less than stable, as such the team speak server that I host on there often needs restarting. Rather than doing the sensible thing and just starting the teamspeak server when the system turns on, I decided to get creative and make a server admin web interface using; apache, php, a sprinkling of html, and a pile of shell scripts. The first step is to get apache and php up and running, then we’ll sort out the php and the scripts.

Installing Apache and Php

Thanks to Ubuntu’s package manager, installing both of these packages is very straight forward. All you need to do is run the following commands:

sudo apt-get install apache2
sudo apt-get install php5
sudo apt-get install libapache2-mod-php5
sudo /etc/init.d/apache2 restart

Once the installation is completed, you have a fully functional web server up and running. Now any files in /var/www/ will be hosted on the server. If you want your website to be available over the internet then you’ll have to forward port 80 or if you want to use a custom port, you’ll have to change Listen 80 to your port of choice in /etc/apache2/ports.conf and then restart your apache server.

Creating the web page

Now that we’ve got apache and php up and running it’s almost time to move on to the fun bit, writing the php script and the html form to trigger it, but first we’ve got to make sure all the bash scripts that we want to run are set up properly and that we know where they are. To keep it simple I’ve stored all the scripts I want to run in `/serverscripts/’ on the root of the system, this way I won’t have to faf around trying to find them if something goes wrong.

Now it’s finally time to write some php to run our scripts, I’ll show you the code first and then explain what it does directly underneath.

<?php
if ($_GET['run']) {
  # This code will run if ?run=true is set.
  exec("sh /PATH/TO/YOUR/SCRIPT.sh");
}
?>

Now that code’s, pretty simple but in case this is your first time with php let me explain what it does. The first line identifies that this piece of code is a php script, this is so you can put it in amongst all the html you’re using on your website. The second line is slightly more interesting, this is an if statement that will trigger if the run variable is set to true in the URL parameters. What does that actually mean I hear you ask? Well it means that if you visit the url MY.IP.ADDRESS/myphppage.php?run=true then the php script will be triggered and run the code. It’s important to note that run can be anything you want it to be, so you should change it to something more specific to the script that you want to run like startteamspeak. Finally we come to the line that actually runs the script. The exec function will just run whatever bash command you put inside of the quotations, in this case sh is the command to run a bash script and then we give it the absolute path to the script that we want to run. The last couple of lines are just closing the brackets and php tags that were opened up at the start of the script.

Now you can save that code in as .php file in /var/www/ and if you navigate to YOUR.IP.ADDRESS/YOURPHPFILE.php?run=true then your script will run, but you won’t be able to see anything on the page yet, in order to do that we need a little bit of Html.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Launch Scripts</title>
</head>
<body>
<h2>Run my script</h2>
<form id="runScripts" method="post" action="?run=true">
<p>To run the script click this button:
<input type="submit" value="Click Me" id="submit" />
</p>
</form>
<p>To run the script click this <a href="?run=true">link</a></p>
</body>
</html>

Most of that html is just setup stuff, the import bits are the two lines in paragraph tags (<p>), these two lines offer two options to insert ?run=true into the URL to trigger the script. The first option is a pretty button and the second is just a plain old link, but I’ll leave the choice of which to use to you. Remember you’ll need to put this code into the php file we made earlier to get it to run properly, and don’t forget to change any instance run to whatever you named your php script. To make it so that you can run, more than one script you just need to repeat this process changing the php script name and the path to the different .sh files you want to run.

Hopefully you’ve got all that working now, but if you don’t feel free to comment below and I’ll do my best to help you along.

Tips and Tricks

If you change exec to echo exec then it’ll return the output of the script and show it on your webpage, but you might need to do some fiddling to get it to display nicely.

Headphone Amp - Fiio E10

2014-02-13T00:00:00+00:00

To go with the Audio Technica ATH-M35s that I recently received as a gift, I decided to purchase a Fiio E10. It’s a small but powerful AMP/DAC combo capable of powering headphones up to an impedance of 300 ohms.

It costs quite a bit less than some similar products, coming in at only sixty bucks. Due to the lower cost I wasn’t expecting anything overly special, so it came as a nice surprise the first time I gave it a whirl that it sounded amazing. The difference between listening to music though the jack on my pc and through the amp is astounding, suddenly the music just comes to life, and it sounds like you’re in the room as they’re recording it.

If you’re looking for a cheap (relatively) headphone amp, then I would definitely recommend the FiiO E10.

Blue Snowball

2014-02-05T00:00:00+00:00

In order to take advantage of my new headphones (Audio Technica ATH-M35s) I decided to buy a standalone microphone so that I didn’t have to switch to my headset to play games and talk. After some research I settled on Blues snowball microphone. It’s a ball shaped USB condenser microphone with a three pattern switch, the first of which is cardioid (heart shape) which is good for doing voice overs or VOIP, the second pattern is the same as the first but -20db which makes it good for loud environments such my dorm room, the third and final pattern is Omni directional which is intended for recording music or conducting interviews.

The sound quality of the microphone is excellent, although it does pick up quite a lot of background noise (I am in a loud environment) which can be a pain. Another issue that I have with it is that it picks up vibrations though I expect this can be fixed if I was willing to invest in a shock mount and a proper mic stand.

Overall I’m very happy with the snowball as despite its issues the quality is still outstanding and it means that I can take advantage of my headphones in all situations giving me a better experience all around.

New Graphics Card – Gigabyte 280x

2014-02-05T00:00:00+00:00

I’ve recently acquired a spanking new graphics card, the Gigabyte Wind force 3x R9 280x. It’s a rather good card, part of AMDs latest range meaning that it supports Mantle a new low level graphics API allowing for to developers to create more efficient more optimised games which means better performance in the games that support. As well as having mantle support the card also features 3GB of GDRR5 memory which should suffice for some time. Aside from the specifications of the card, it’s also very pretty card which is perhaps the most important factor when choosing a graphics card!

Server Update

2013-10-12T00:00:00+00:00

I haven’t done much with my server in a while, I had planned on sticking it in to a Fractal Design R4 to help reduce the noise, however to save costs I decided against this. Instead I’ve decided to replace the old, unbranded power supply with a nice, quite low power (ish) one from the Corsair builder series range. As this power supply is modular it also allowed me to improve the cable management and airflow around the case. I was also able to upgrade the processor, to the quad core from my main rig as I got a new processor for that. Both of these improvements mean that everything I run on it is quite a lot faster and it does so silently.

Review - CM QuickFire TK

2013-10-07T00:00:00+00:00

I recently got a new keyboard, the Cooler Master QuickFire TK. It’s my second mechanical keyboard the first being the Razer Black widow, this time round I opted for brown switches similar to the blues in my black widow they have quite a nice tactile response however they are much, much quieter.

It arrived in the usual classy style of Overclockers with a free packet of Haribo, in a nice plain box. Inside the plain box was another rather less plain box, which contained the keyboard. The keyboard came in a dust cover, which was a nice surprise.

The keyboard itself has excellent build quality; the keys feel solid despite only being ABS keycaps. The board also feature a white backboard which really makes the lighting pop; speaking of the lighting it has three different modes and several different levels of brightness. It also features the standard media keys by combining the “Fn” key with the function keys, as well as N key roll over. The thing that makes this keyboard stand out over others is the fact that it combines the number pad with the arrows keys and other keys around that area; this allows the keyboard to maintain full functionality whilst being the same size as a ten keyless.

Overall I’m quite fond of this keyboard; I prefer it to my black widow the build quality and browns are far superior for my needs. Although I do miss typing on blues, so I’m considering purchasing a KBC Poker II with blues for typing on.

New Processor and My First Venture into Water Cooling

2013-10-07T00:00:00+00:00

I just got a new processor for my main desktop PC, the AMD FX 8350. It’s an eight core processor running at 4GHz when stock, however I’ve overclocked it to 4.6GHz just because I can thanks to my first venture into water cooling albeit not a very extravagant one. I got a H100, which is a closed loop solution from Corsair for cooling processors; I decided to get a water cooler so that I could keep my temps nice and low when overclocking.

The installation of the processor itself was quite simple, however the H100 was slightly more difficult and definitely required two pairs of hands; fortunately Harvey was on hand to help out. After somehow managing to support it whilst screwing the heat sink to the socket and avoiding twisting the pipes out of shape, we managed to attach the radiator to the case. After installing my H100 we moved on to Harvey’s, which was even more difficult despite his Antec 900 being almost twice the size of my Fractal Design Arc. In the end in order to squeeze it in we had to do some strategic bending of the case.

After installing the H100s we set about overclocking, which after some research is a simple but time consuming process. I managed to get mine to just over 4.6GHz whilst still keeping it at a nice 38 degrees with the water cooler on low.

Fractal Design Arc Midi R2 - Update

2013-08-16T00:00:00+00:00

In my previous review of the Arc Midi R2 that you can find here, I made two complaints. One was that the fan controller didn’t work, the other that the window was tinted making it difficult to see the components.

Since that review, both issues have been rectified. The first was resolved after I contacted fractal design and they sent me a replacement controller rather quickly, which was quite impressive. I installed the fan controller and thankfully this one worked wonderfully. The installation itself was reasonably simple; two screws secured the old controller after unscrewing them and positioning the new controller it was just a case of plugging it in to a Molex connector.

To solve the tinted window issue I purchased a set of Akasa Vegas white LEDs from overclockers, the product is simply a strip of rather bright LEDs with double sided tape on the reverse side of it to attach to the case. It’s powered by a Molex connector at one end of the strip, at the other end is a three pin connector allowing you to daisy chain multiple strips together.

I think the lighting improves the look of the case quite a lot, although I made need to invest in a second strip to remove the shadow cast by the graphics card. Here’s what it looks like at night all lit up and pretty.

Review - Fractal Design Arc Midi R2

2013-07-03T00:00:00+00:00

As I mentioned in my previous post I’ve bought myself a new case, the Fractal Design Arc Midi R2. It arrived on Tuesday and I promptly opened it up and installed my components in to the new case. It came in the usual box with some polystyrene to keep it safe, a user manual and a box full of a ridiculous amount of spare screws (not that I’m complaining).

The case looks damn good, which is one of the many reasons I chose it. It has a large vent on the front for airflow as wells as one along the top and one under the bottom mounted PSU. The only slight issue I have with the looks is that the side window is tinted, which makes it slightly harder to see through but I plan on putting some lights in the case which should make it quite a bit easier.

As I mentioned on the front is a vent, behind which you can fit two 140mm fans (one of which is included), the vent also features a dust filter and can be removed simply by pressing on the top of the filter.

The case can also fit another three 140mm fans with room for a further two in the back and bottom of the case. It comes with one in the top and one in the back for a total of 3 included fans. The Arc Midi also has plenty of room for water cooling with the capability of fitting a 240mm radiator in the top and front as well as 120mm ones in the rear and bottom of the case. I’m looking forward to installing my corsair H100 in the top when it arrives later this week (hopefully). Also as with the front the top vent is removable and holds a dust filter underneath it.

The front panel of the case features two USB 3.0 ports as well as the usual power button, hdd led, power led, audio jacks and a reset switch that it very hard to press accidentally. The other feature is what makes it stand out from most, which is the built in fan controller which supports up to three fans and has three different voltages to choose from. I really like this feature, but a small feature has arisen being the fact that if I try to change the voltage whilst my pc is on it promptly crashes, I’ve contacted Fractal about this and hopefully it will be resolved quickly.

The case has eight hard drive bays, split into two cages one which can hold five the other three, they are both fully removable to allow you to get better air flow, install thick front radiators or fit even the longest of graphics cards. I currently have the top bay removed for better air flow, but kept the lower one to store my 3TB HDD and my 256GB SDD. Which brings me nicely to another great feature of this case; all of the drive bays have full SDD support as well as rubber grommets to reduce nasty hard drive vibrations. The case also has room for two SSD’s to be installed on the back plate so you’ll still have somewhere to store your hard drives if you decide to go cage less.

The cable management is excellent; there are more than enough holes to thread cables though and plenty of space to hide cables behind the back plate as well as a number of cable tie points to keep them quite tidy. The only issue I had is that the cables that come with my power supply aren’t the longest or the most flexible, this prevented me from hiding the 6 pin graphics card cables as well as I’d of liked.

Overall the case is incredibly nice to work with, far superior to my old Antec 300 and I would highly recommend it to anyone looking to build a PC. If you’re interested in seeing the full album of pictures they can be found here.