Added lesson 7

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diff --git a/www/devmaster/lesson5.html b/www/devmaster/lesson5.html
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@@ -33,17 +33,17 @@ OpenAL Tutorials from DevMaster.net. Reprinted with Permission.<br>
   Maurais<br>
   </a>Adapted For Java By: <a href="[email protected]">Athomas 
   Goldberg </a></p>
-<p>At this point in the OpenAL series I will show one method of having your buffers 
-  be shared among many sources. This is a very logical and natural step, and it 
-  is so easy that some of you may have already done this yourself. If you have 
-  you may just skip this tutorial in total and move on. But for those keeners 
-  who want to read all of the info I've got to give, you may find this interesting. 
-  Plus, we will be implementing the Alc layer directly so that we can use some 
-  of that knowledge gained in lesson 4. On top of that we will create a program 
-  you might even use!</p>
-<p>Well, here we go. I've decided to only go over bits of the code that are significant, 
-  since most of the code has been repeated so far in the series. Check out the 
-  full source code in the download.</p>
+<p align="justify">At this point in the OpenAL series I will show one method of 
+  having your buffers be shared among many sources. This is a very logical and 
+  natural step, and it is so easy that some of you may have already done this 
+  yourself. If you have you may just skip this tutorial in total and move on. 
+  But for those keeners who want to read all of the info I've got to give, you 
+  may find this interesting. Plus, we will be implementing the Alc layer directly 
+  so that we can use some of that knowledge gained in lesson 4. On top of that 
+  we will create a program you might even use!</p>
+<p align="justify">Well, here we go. I've decided to only go over bits of the 
+  code that are significant, since most of the code has been repeated so far in 
+  the series. Check out the full source code in the download.</p>
 <pre class=code><span class=codeComment><font color="#0000FF">static</font> ALC alc;
 <font color="#0000FF">static</font> AL al;<font color="#006600">
 
@@ -64,13 +64,13 @@ OpenAL Tutorials from DevMaster.net. Reprinted with Permission.<br>
 Vector sources = <font color="#0000FF">new </font>Vector();
 
 </pre>
-<p>First I've written out a few macros that we can use to index the buffer array. 
-  We will be using several wav files so we need quite a few buffers here. Instead 
-  of using an array for storing the sources we will use a Vector. We chose to 
-  do this because it allows us to have a dynamic number of sources. We can just 
-  keep adding sources to the scene until OpenAL runs out of them. This is also 
-  the first tutorial where we will deal with sources as being a resource that 
-  will run out. And yes, they will run out; they are finite.</p>
+<p align="justify">First I've written out a few macros that we can use to index 
+  the buffer array. We will be using several wav files so we need quite a few 
+  buffers here. Instead of using an array for storing the sources we will use 
+  a Vector. We chose to do this because it allows us to have a dynamic number 
+  of sources. We can just keep adding sources to the scene until OpenAL runs out 
+  of them. This is also the first tutorial where we will deal with sources as 
+  being a resource that will run out. And yes, they will run out; they are finite.</p>
 <pre class=code><font color="#0000FF">static int </font>initOpenAL() {
  
     ALC.Device device;
@@ -99,8 +99,8 @@ Vector sources = <font color="#0000FF">new </font>Vector();
     <span class=codeKeyword><font color="#0000FF">return</font></span> AL.AL_TRUE;
 }
 </pre>
-<p>This is some sample code from what we learned in the last tutorial. We get 
-  a handle to the device &quot;DirectSound3D&quot;, and then obtain a rendering 
+<p align="justify">This is some sample code from what we learned in the last tutorial. 
+  We get a handle to the device &quot;DirectSound3D&quot;, and then obtain a rendering 
   context for our application. This context is set to current and the function 
   will check if everything went smoothly before we return success.</p>
 <pre class=code><span class=codeKeyword><font color="#0000FF">static void</font></span> exitOpenAL() {
@@ -121,16 +121,16 @@ Vector sources = <font color="#0000FF">new </font>Vector();
     alc.alcCloseDevice(curDevice);
 }
 </pre>
-<p>This will do the opposite we did in the previous code. It retrieves the context 
-  and device that our application was using and releases them. It also sets the 
-  current context to null (the default) which will suspend the processing of any 
-  data sent to OpenAL. It is important to reset the current context to null or 
-  else you will have an invalid context trying to process data. The results of 
-  doing this can be unpredictable.</p>
-<p>If you are using a multi-context application you may need to have a more advanced 
-  way of dealing with initialization and shutdown. I would recommend making all 
-  devices and contexts global and closing them individually, rather than retrieving 
-  the current context.</p>
+<p align="justify">This will do the opposite we did in the previous code. It retrieves 
+  the context and device that our application was using and releases them. It 
+  also sets the current context to null (the default) which will suspend the processing 
+  of any data sent to OpenAL. It is important to reset the current context to 
+  null or else you will have an invalid context trying to process data. The results 
+  of doing this can be unpredictable.</p>
+<p align="justify">If you are using a multi-context application you may need to 
+  have a more advanced way of dealing with initialization and shutdown. I would 
+  recommend making all devices and contexts global and closing them individually, 
+  rather than retrieving the current context.</p>
 <pre class=code><font color="#0000FF">static int </font>loadALData() {
     <font color="#006600"><span class=codeComment>// Variables to load into.</span></font>
     <font color="#0000FF">int</font>[] format = new <font color="#0000FF">int</font>[1];
@@ -176,8 +176,8 @@ Vector sources = <font color="#0000FF">new </font>Vector();
     <span class=codeKeyword><font color="#0000FF">return</font></span> AL.AL_TRUE;
 }
 </pre>
-<p>We've totally removed the source generation from this function. That's because 
-  from now on we will be initializing the sources separately.</p>
+<p align="justify">We've totally removed the source generation from this function. 
+  That's because from now on we will be initializing the sources separately.</p>
 <pre class=code><span class=codeKeyword><font color="#0000FF">static void</font></span><font color="#0000FF"> </font>addSource(int type) {
     <font color="#0000FF">int[]</font> source = <font color="#0000FF">new int</font>[1];
 
@@ -201,12 +201,12 @@ Vector sources = <font color="#0000FF">new </font>Vector();
 }
 
 </pre>
-<p>Here's the function that will generate the sources for us. This function will 
-  generate a single source for any one of the loaded buffers we generated in the 
-  previous source. Given the buffer index 'type', which is one of the macros we 
-  created right from the start of this tutorial. We do an error check to make 
-  sure we have a source to play (like I said, they are finite). If a source cannot 
-  be allocated then the program will exit.</p>
+<p align="justify">Here's the function that will generate the sources for us. 
+  This function will generate a single source for any one of the loaded buffers 
+  we generated in the previous source. Given the buffer index 'type', which is 
+  one of the macros we created right from the start of this tutorial. We do an 
+  error check to make sure we have a source to play (like I said, they are finite). 
+  If a source cannot be allocated then the program will exit.</p>
 <pre class=code><span class=codeKeyword><font color="#0000FF">static void</font></span><font color="#0000FF"> </font>killALData() {
 
     Iterator iter = sources.iterator();
@@ -218,9 +218,9 @@ Vector sources = <font color="#0000FF">new </font>Vector();
     exitOpenAL();
 }
 </pre>
-<p>This function has been modified a bit to accommodate the Vector. We have to 
-  delete each source in the list individually and then clear the list which will 
-  effectively destroy it.</p>
+<p align="justify">This function has been modified a bit to accommodate the Vector. 
+  We have to delete each source in the list individually and then clear the list 
+  which will effectively destroy it.</p>
 <pre class=code><font color="#0000FF">    char</font>[] c = <font color="#0000FF">new char</font>[1];
 
 <font color="#0000FF">    </font><font color="#0000FF">while</font>(c[0] != 'q') {	
@@ -248,19 +248,20 @@ Vector sources = <font color="#0000FF">new </font>Vector();
 			System.exit(1);
 <font color="#0000FF">    </font><font color="#0000FF">    </font>}
 <font color="#0000FF">    </font>}</pre>
-<p>Here is the programs inner loop taken straight out of our main. Basically it 
-  waits for some keyboard input and on certain key hits it will create a new source 
-  of a certain type and add it to the audio scene. Essentially what we have created 
-  here is something like one of those nature tapes that people listen to for relaxation. 
-  Ours is a little better since it allows the user to customize which sounds that 
-  they want in the background. Pretty neat eh? I've been listening to mine while 
-  I code. It's a Zen experience (I'm listening to it right now).</p>
-<p>The program can be expanded for using more wav files, and have the added feature 
-  of placing the sources around the scene in arbitrary positions. You could even 
-  allow for sources to play with a given frequency rather than have them loop. 
-  However this would require GUI routines that go beyond the scope of the tutorial. 
-  A full featured &quot;Weathering Engine&quot; would be a nifty program to make 
-  though. ;)</p>
+<p align="justify">Here is the programs inner loop taken straight out of our main. 
+  Basically it waits for some keyboard input and on certain key hits it will create 
+  a new source of a certain type and add it to the audio scene. Essentially what 
+  we have created here is something like one of those nature tapes that people 
+  listen to for relaxation. Ours is a little better since it allows the user to 
+  customize which sounds that they want in the background. Pretty neat eh? I've 
+  been listening to mine while I code. It's a Zen experience (I'm listening to 
+  it right now).</p>
+<p align="justify">The program can be expanded for using more wav files, and have 
+  the added feature of placing the sources around the scene in arbitrary positions. 
+  You could even allow for sources to play with a given frequency rather than 
+  have them loop. However this would require GUI routines that go beyond the scope 
+  of the tutorial. A full featured &quot;Weathering Engine&quot; would be a nifty 
+  program to make though. ;)</p>
 <p><a href="lesson5.zip">Download the Java Files and Ant build script</a></p>
 <table border="0" cellspacing="1" style="border-collapse: collapse" width="100%" id="AutoNumber2" bgcolor="#666699">
   <tr> 
diff --git a/www/devmaster/lesson7.html b/www/devmaster/lesson7.html
new file mode 100644
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@@ -0,0 +1,178 @@
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+OpenAL Tutorials from DevMaster.net. Reprinted with Permission.<br>
+<br>
+<table border="0" cellspacing="0" style="border-collapse: collapse" width="100%" cellpadding="0" id="AutoNumber1" height="12" bgcolor="#666699">
+  <tr> 
+    <td width="47%" height="12" valign="middle"><p><b><font color="#FFFFFF">OpenAL 
+        Tutorials</font></b></p></td>
+    <td width="53%" height="12" align="right" valign="middle"><p align="right"><a href="http://devmaster.net/"><font color="#66FF99">DevMaster.net</font></a></p></td>
+  </tr>
+</table>
+<p class="ArticleTitle"><font size="5">The Doppler Effect<br>
+  </font><font color="#000000" size="4"><strong>Lesson 7</strong></font></p>
+<p align="right" class="ArticleAuthor">Author: <a href="mailto:[email protected]">Jesse 
+  Maurais</a><br>
+  Adapted For Java By: <a href="mailto:[email protected]">Athomas Goldberg</a></p>
+<h1>A Look at Real-World Physics</h1>
+<p>I know this will be boring review for anyone with a course in high school 
+physics, but lets humour ourselves. The Doppler effect can be a very tricky 
+concept for some people, but it is a logical process, and kind of interesting 
+when you get right down to it. To begin understanding the Doppler effect we 
+first must start to understand what a &quot;sound&quot; really is. Basically a sound is 
+your minds interpretation of a compression wave that is traveling through the 
+air. Whenever the air becomes disturbed it starts a wave which compresses the 
+air particles around it. This wave travels outward from it's point of origin. 
+Consider the following diagram.</p>
+<p><img src="sound_waves.jpg" width="150" height="132" hspace="5" vspace="0" border="0" align="left">In this diagram 
+(on the left) the big red &quot;S&quot; stands for the sources position, and the big 
+red &quot;L&quot; stands for (you guessed it), the Listener's position. Both source and 
+Listener are not moving. The source is emitting compression waves outward, which 
+are represented in this diagram by the blue circles. The Listener is 
+experiencing the sound exactly as it is being made in this diagram. The Doppler 
+effect is not actually present in this example since there is no motion; the 
+Doppler effect only describes the warping of sound due to motion.</p>
+<p>What you should try to do is picture this diagram animated. When the source 
+emits a wave (the circles) it will look as though it is growing away from it's 
+point of origin, which is the sources position. A good example of a similar 
+effect is the ripples in a pond. When you throw a pebble into a calm body of 
+water it will emit waves which constantly move away from the point of impact. 
+Believe it or not this occurs from the exact same physical properties. But what 
+does this have to do with the Doppler effect? Check out the next diagram (on the 
+right).</p>
+
+<p>
+<img src="doppler_effect.jpg" width="150" height="132" hspace="5" border="0" align="right">Wow, what's going on here? The source is now in motion, indicated by the 
+little red arrow. In fact the source is now moving towards the Listener with an 
+implied velocity. Notice particularly that the waves (circles) are being 
+displaced inside each other. The displacement follows the approximate path of 
+the source which emits them. This is the key to the Doppler effect. Essentially 
+what has happened is that the source has emitted a wave at different points in 
+it's path of travel. The waves it emits do not move with it, but continue on 
+their own path of travel from the point they were emitted.</p>
+<p>So how does this effect the perceived sound by the Listener? Well, notice too 
+in the last diagram that the waves (circles) that are between the source and the 
+Listener are kind of compressed together. This will cause the sound waves to run 
+together, which in turn causes the perceived sound seem like it's faster. What 
+we are talking about here is frequency. The distances between the waves effects 
+the frequency of the sound. When the source that emits the sound is in motion, 
+it causes a change in frequency. You may notice too that distance between the 
+waves varies at different points in space. For example, on the opposite side of 
+the moving source (anywhere along the previous path of travel) the distances are 
+actually wider, so the frequency will be lower (the distance and frequency have 
+an inverse relationship). What this implies is that the frequency perceived by 
+the Listener is relative to where the Listener is standing. </p>
+<p>The motion of the Listener can also affect the frequency. This one is a 
+little harder to picture though. If the source is still, and the Listener is 
+moving toward the source, then the perceived frequency by the Listener will be 
+warped in the same exact manner that we described for the moving source. </p>
+<p>If you still have trouble picturing this, consider the following two 
+diagrams:</p>
+<p align="center"><img border="0" src="sin_wave.jpg" width="255" height="135">&nbsp;&nbsp;
+<img border="0" src="compress_sin_wave.jpg" width="255" height="135"></p>
+<p>These two diagrams will represent the sound in the form of a sine wave. Look 
+at the first one. Think of the peaks as the instance of the wave. The very top 
+point of the wave will be the same as the instance of the blue circle in the 
+previous set of diagrams. The valleys will be like the spaces in between the 
+blue circles. The second diagram represents a compressed wave. When you compare 
+the two you will notice an obvious difference. The second diagram simply has 
+more wave occurrences in the same amount of space. Other ways of saying this are 
+that they occur more often, with a greater regularity, or with a greater 
+frequency. </p>
+<p>For anyone who is interested in some added information: The velocity of the 
+waves is the speed of sound. If the velocity of the source is greater than that 
+of the wave, then the source is breaking the sound barrier.</p>
+<h1>The Physics of OpenAL</h1>
+
+<p>Ok, either you have understood my ramblings on the Doppler effect from above, 
+or you have skipped it because you already have full knowledge of the Doppler 
+effect and just want to know how it effects the OpenAL rendering pipeline. I 
+think the best start to his section will be to quote the OpenAL spec directly:</p>
+<blockquote>
+  <p><i>&quot;The Doppler Effect depends on the velocities of Source and Listener 
+  relative to the medium, and the propagation speed of sound in that medium.&quot; - 
+  chapter 3, subsection 7&quot;</i></p>
+</blockquote>
+<p>We can take this to mean that there are 3 factors which are going to affect 
+the final frequency of the sound heard by the Listener. These factors are the 
+velocity of the source, the velocity of the Listener, and a predefined speed of 
+sound. </p>
+<p>When we refer to a &quot;medium&quot;, what we mean is the kind of material that both 
+the source and Listener are &quot;in&quot;. For example, sounds that are heard from 
+underwater are much different than sounds that are heard in the open air. Air 
+and water are examples of different mediums. The reason that sound is so 
+different between these mediums has to do with the particle density. As we said 
+before, sound is nothing but the motion of particles in the air. In a medium 
+with a much greater particle density the sound will be much different because 
+the particles are in closer contact. When they are in closer contact it allows 
+for the wave to travel much better. As an example of the opposite, think of 
+outer space. In outer space there is an extremely low particle density. In fact 
+there is only a few very light particles (mostly hydrogen) scattered about. This 
+is why no sound can be heard from space. </p>
+
+<p>Ok, lets get back on topic. OpenAL calculates the Doppler effect internally 
+for us, so we need only define a few parameters that will effect the 
+calculation. We would do this in case we don't want a realistic rendering. 
+Rather if want to exaggerate or deemphasize the effect. The calculation goes 
+like this.</p>
+<p><span class="codeNormal">&nbsp;&nbsp;&nbsp; shift = DOPPLER_FACTOR * freq * (DOPPLER_VELOCITY 
+- l.velocity) / (DOPPLER_VELOCITY + s.velocity)</span></p>
+<p>Constants are written in all caps to differentiate. The &quot;l&quot; and &quot;s&quot; variables 
+are the Listener and source respectively. &quot;freq&quot; is the initial unaltered 
+frequency of the emitting wave, and &quot;shift&quot; is the altered frequency of the 
+wave. The term &quot;shift&quot; is the proper way to address the altered frequency and 
+will be used from now on. This final shifted frequency will be sampled by OpenAL 
+for all audio streaming that is affected. </p>
+
+<p>We already know that we can define the velocity of both source and Listener 
+by using the 'AL_VELOCITY' field to 'alListenerfv' and 'alSourcefv'. The 'freq' 
+parameter comes straight from the buffer properties when it was loaded from 
+file. To set the constant values the following functions are provided for us.</p>
+<pre class=code><font color="#0000FF">public void </font>alDopplerFactor(<font color="#0000FF">float</font> factor);
+<font color="#0000FF">public void </font>alDopplerVelocity(<font color="#0000FF">float</font> velocity);
+</pre>
+<p>For 'alDopplerFactor' any non-negative value will suffice. Passing a negative 
+value will raise an error of 'AL_INVALID_VALUE', and the whole command will be 
+ignored. Passing zero is a perfectly valid argument. Doing this will disable the 
+Doppler effect and may in fact help overall performance (but won't be as 
+realistic). The effect of the Doppler factor will directly change the magnitude 
+of the equation. A value of 1.0 will not change the effect at all. Passing 
+anything between 0.0 and 1.0 will minimize the Doppler effect, and anything 
+greater than 1.0 will maximize the effect. </p>
+<p>For 'alDopplerVelocity' any non-negative non-zero value will suffice. Passing 
+either a negative or a zero will raise an error of 'AL_INVALID_VALUE', and the 
+whole command will be ignored. The Doppler velocity is essentially the speed of 
+sound. Setting this will be like setting how fast sound can move through the 
+medium. OpenAL has no sense of medium, but setting the velocity will give the 
+effect of a medium. OpenAL also has no sense of units (kilometer, miles, 
+parsecs), so keep that in mind when you set this value so it is consistent with 
+all other notions of units that you have defined.</p></p>
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diff --git a/www/devmaster/sin_wave.jpg b/www/devmaster/sin_wave.jpg
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