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 <div class="blog">
 <h1 id="NAME">
-Updates, Falling Block Game, and Hack Fest
+SDL RC 2.5 decides to play with PDL
 </h1>
 <div class="CONTENT">
-<div style="text-align: right;"><i>Silent but active,<br />Small but deadly. <br /></i><br /></div><br /><br /><h3>Updates</h3>Ok so my blog posts have gone down a bit due to me using my fingers for coding. We have started to get some updates to SDL docs so that good. Also some of the tutorials are shaping up. This is what I have been hacking this past week.<br /><br /><br /><br /><div class="separator" style="clear: both; text-align: center;"><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="http://2.bp.blogspot.com/_NnqjAQEn1Xo/SrmNTm9UkKI/AAAAAAAAAA0/S0XNvXsp9u4/s1600-h/tetris.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://2.bp.blogspot.com/_NnqjAQEn1Xo/SrmNTm9UkKI/AAAAAAAAAA0/S0XNvXsp9u4/s320/tetris.jpg" /></a><br /></div><br /><br /><br /><br />You can grab the <a href="http://github.com/kthakore/TetrisPL">code</a>. Note you will have to install deps yourself. Read the README file. It is not a tutorial yet, because it was hacked together in ~50 hours. But it playable now. During building this I found out that MacOSX (and Snow Leopard) has died again.<br /><br /><h3>Hackfest</h3>So with dngor's help this sunday (27/09/09) we will have a hackfest to fix MacOSX support. Anyone with a MacOSX and wants to help is welcome on <a href="http://widget.mibbit.com/?settings=89f140215d60860684cee2f6a917607f&amp;server=irc.perl.org&amp;channel=%23sdl">#sdl irc.perl.org</a>. We will also try to fix up a lot of docs and the tutorial for a early next week release. Also if we can we will migrate to the new site.<div class="blogger-post-footer"><img width='1' height='1' src='https://blogger.googleusercontent.com/tracker/3102167581424744259-7382145297295717151?l=yapgh.blogspot.com'/></div></div>
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+<i>PDL provides great number crunching capabilities to Perl and SDL provides game-developer quality real-time bitmapping and sound.<br />
+You can use PDL and SDL together to create real-time,<br />
+responsive animations and simulations.<br />
+In this section we will go through the pleasures and pitfalls of working with both powerhouse libraries.</i> <b>-- David Mertnes</b><br />
+<br />
+<br />
+<h1>Creating a SDL Surface piddle</h1><br />
+PDL's core type is a piddle.<br />
+Once a piddle is provided to PDL it can go do a numerous amounts of things.<br />
+Please see the example in '<a href="http://github.com/kthakore/SDL_perl/blob/master/examples/cookbook/pdl.pl">examples/cookbook/pdl.pl</a>' in github.<br />
+<br />
+<h3>Creating a simple piddle</h3><br />
+First lets get the right modules.<br />
+<br />
+<pre style='color:#d1d1d1;background:#000000;'>  <span style='color:#e66170; font-weight:bold; '>use</span> <span style='color:#b060b0; '>PDL;</span>
+  <span style='color:#e66170; font-weight:bold; '>use</span> <span style='color:#904050; '>SDL</span><span style='color:#d2cd86; '>::</span><span style='color:#904050; '>Rect</span><span style='color:#b060b0; '>;</span>
+  <span style='color:#e66170; font-weight:bold; '>use</span> <span style='color:#904050; '>SDL</span><span style='color:#d2cd86; '>::</span><span style='color:#904050; '>Video</span><span style='color:#b060b0; '>;</span>
+  <span style='color:#e66170; font-weight:bold; '>use</span> <span style='color:#904050; '>SDL</span><span style='color:#d2cd86; '>::</span><span style='color:#904050; '>Surface</span><span style='color:#b060b0; '>;</span>
+  <span style='color:#e66170; font-weight:bold; '>use</span> <span style='color:#904050; '>SDL</span><span style='color:#d2cd86; '>::</span><span style='color:#904050; '>PixelFormat</span><span style='color:#b060b0; '>;</span>
+</pre><br />
+Suppose you want a surface of size (200,400) and 32 bit (RGBA).<br />
+<br />
+<pre style='color:#d1d1d1;background:#000000;'><span style='color:#e66170; font-weight:bold; '>my</span> <span style='color:#d2cd86; '>(</span> $bytes_per_pixel<span style='color:#d2cd86; '>,</span> $width<span style='color:#d2cd86; '>,</span> $height <span style='color:#d2cd86; '>)</span> <span style='color:#d2cd86; '>=</span> <span style='color:#d2cd86; '>(</span> <span style='color:#00a800; '>4</span><span style='color:#d2cd86; '>,</span> <span style='color:#00a800; '>200</span><span style='color:#d2cd86; '>,</span> <span style='color:#00a800; '>400</span> <span style='color:#d2cd86; '>)</span><span style='color:#b060b0; '>;</span>
+</pre><br />
+Define the <b>$width</b>, <b>$height</b> and <b>$bytes_per_pixel</b>. Your <b>$bytes_per_pixel</b> is the number of bits (in this case 32) divided by 8 bits per byte. Therefore for our 32 bpp we have 4 Bpp;<br />
+<br />
+<pre style='color:#d1d1d1;background:#000000;'><span style='color:#e66170; font-weight:bold; '>my</span> $piddle  <span style='color:#d2cd86; '>=</span> zeros<span style='color:#d2cd86; '>(</span> byte<span style='color:#d2cd86; '>,</span> $bytes_per_pixel<span style='color:#d2cd86; '>,</span> $width<span style='color:#d2cd86; '>,</span> $height <span style='color:#d2cd86; '>)</span><span style='color:#b060b0; '>;</span>
+</pre><br />
+Create a normal $piddle with zeros, byte format and the Bpp x width x height dimensions.<br />
+<br />
+<pre style='color:#d1d1d1;background:#000000;'><span style='color:#e66170; font-weight:bold; '>my</span> $pointer <span style='color:#d2cd86; '>=</span> $piddle<span style='color:#d2cd86; '>-></span>get_dataref<span style='color:#d2cd86; '>(</span><span style='color:#d2cd86; '>)</span><span style='color:#b060b0; '>;</span>
+</pre><br />
+Here is where we get the acutal data the piddle is pointing to. We will have SDL create a new surface from this function.<br />
+<br />
+<pre style='color:#d1d1d1;background:#000000;'><span style='color:#e66170; font-weight:bold; '>my</span> $surface <span style='color:#d2cd86; '>=</span> <span style='color:#904050; '>SDL</span><span style='color:#d2cd86; '>::</span><span style='color:#904050; '>Surface</span><span style='color:#d2cd86; '>-></span>new_from<span style='color:#d2cd86; '>(</span> $pointer<span style='color:#d2cd86; '>,</span> $width<span style='color:#d2cd86; '>,</span> $height<span style='color:#d2cd86; '>,</span> <span style='color:#00a800; '>32</span><span style='color:#d2cd86; '>,</span>
+        $width <span style='color:#d2cd86; '>*</span> $bytes_per_pixel <span style='color:#d2cd86; '>)</span><span style='color:#b060b0; '>;</span>
+</pre><br />
+Using the same dimensions we create the surface using <b>SDL::Surface->new_form()</b>. The <b>$width * $Bpp</b> is the scanline (pitch) of the surface in bytes.<br />
+<br />
+<pre style='color:#d1d1d1;background:#000000;'><span style='color:#e66170; font-weight:bold; '>warn</span> <span style='color:#00c4c4; '>"Made surface of </span><span style='color:#00c4c4; '>$width</span><span style='color:#00c4c4; '>, </span><span style='color:#00c4c4; '>$height</span><span style='color:#00c4c4; '> and "</span><span style='color:#d2cd86; '>.</span> $surface<span style='color:#d2cd86; '>-></span>format<span style='color:#d2cd86; '>-></span>BytesPerPixel<span style='color:#b060b0; '>;</span>
+   <span style='color:#e66170; font-weight:bold; '>return</span> <span style='color:#d2cd86; '>(</span> $piddle<span style='color:#d2cd86; '>,</span> $surface <span style='color:#d2cd86; '>)</span><span style='color:#b060b0; '>;</span>
+</pre><br />
+Finally make sure that the surface acutally has the correct dimensions we gave.<br />
+<br />
+<b>NOTE:</b> <b>$surface->format->BytesPerPixel</b> must return 1,2,3,4. !!<br />
+<br />
+Now you can blit and use the surface as needed; and do PDL operations as required.<br />
+<br />
+<h3>Operating on the Surface safely</h3><br />
+To make sure SDL is in sync with the data. You must call SDL::Video::lock <b>before</b> doing PDL operations on the piddle.<br />
+<br />
+<pre><pre style='color:#d1d1d1;background:#000000;'><span style='color:#904050; '>SDL</span><span style='color:#d2cd86; '>::</span><span style='color:#904050; '>Video</span><span style='color:#d2cd86; '>:</span><span style='color:#d2cd86; '>:</span>lock_surface<span style='color:#d2cd86; '>(</span>$surface<span style='color:#d2cd86; '>)</span><span style='color:#b060b0; '>;</span>
+ 
+    $piddle <span style='color:#d2cd86; '>(</span> <span style='color:#d2cd86; '>:</span><span style='color:#d2cd86; '>,</span> <span style='color:#00a800; '>0</span> <span style='color:#d2cd86; '>:</span> <span style='color:#e66170; font-weight:bold; '>rand</span><span style='color:#d2cd86; '>(</span><span style='color:#00a800; '>400</span><span style='color:#d2cd86; '>)</span><span style='color:#d2cd86; '>,</span> <span style='color:#00a800; '>0</span> <span style='color:#d2cd86; '>:</span> <span style='color:#e66170; font-weight:bold; '>rand</span><span style='color:#d2cd86; '>(</span><span style='color:#00a800; '>200</span><span style='color:#d2cd86; '>)</span> <span style='color:#d2cd86; '>)</span> <span style='color:#d2cd86; '>.</span><span style='color:#d2cd86; '>=</span>   pdl<span style='color:#d2cd86; '>(</span> <span style='color:#e66170; font-weight:bold; '>rand</span><span style='color:#d2cd86; '>(</span><span style='color:#00a800; '>225</span><span style='color:#d2cd86; '>)</span><span style='color:#d2cd86; '>,</span> <span style='color:#e66170; font-weight:bold; '>rand</span><span style='color:#d2cd86; '>(</span><span style='color:#00a800; '>225</span><span style='color:#d2cd86; '>)</span><span style='color:#d2cd86; '>,</span> <span style='color:#e66170; font-weight:bold; '>rand</span><span style='color:#d2cd86; '>(</span><span style='color:#00a800; '>255</span><span style='color:#d2cd86; '>)</span><span style='color:#d2cd86; '>,</span> <span style='color:#00a800; '>255</span> <span style='color:#d2cd86; '>)</span><span style='color:#b060b0; '>;</span>
+</pre></pre><br />
+After that you can unlock the surface to blit.<br />
+<br />
+<pre style='color:#d1d1d1;background:#000000;'><span style='color:#904050; '>SDL</span><span style='color:#d2cd86; '>::</span><span style='color:#904050; '>Video</span><span style='color:#d2cd86; '>:</span><span style='color:#d2cd86; '>:</span>unlock_surface<span style='color:#d2cd86; '>(</span>$surface<span style='color:#d2cd86; '>)</span><span style='color:#b060b0; '>;</span>
+</pre><br />
+<h3>Errors due to BPP at blitting</h3><br />
+When blitting the new surface check for the return value to see if there has been a problem.<br />
+<br />
+<pre style='color:#d1d1d1;background:#000000;'><span style='color:#e66170; font-weight:bold; '>my</span> $b <span style='color:#d2cd86; '>=</span> <span style='color:#904050; '>SDL</span><span style='color:#d2cd86; '>::</span><span style='color:#904050; '>Video</span><span style='color:#d2cd86; '>:</span><span style='color:#d2cd86; '>:</span>blit_surface<span style='color:#d2cd86; '>(</span>
+        $surface<span style='color:#d2cd86; '>,</span>  <span style='color:#904050; '>SDL</span><span style='color:#d2cd86; '>::</span><span style='color:#904050; '>Rect</span><span style='color:#d2cd86; '>-></span>new<span style='color:#d2cd86; '>(</span> <span style='color:#00a800; '>0</span><span style='color:#d2cd86; '>,</span> <span style='color:#00a800; '>0</span><span style='color:#d2cd86; '>,</span> $surface<span style='color:#d2cd86; '>-></span>w<span style='color:#d2cd86; '>,</span> $surface<span style='color:#d2cd86; '>-></span>h <span style='color:#d2cd86; '>)</span><span style='color:#d2cd86; '>,</span>
+        $app<span style='color:#d2cd86; '>,</span> <span style='color:#904050; '>SDL</span><span style='color:#d2cd86; '>::</span><span style='color:#904050; '>Rect</span><span style='color:#d2cd86; '>-></span>new<span style='color:#d2cd86; '>(</span>  <span style='color:#d2cd86; '>(</span> $app<span style='color:#d2cd86; '>-></span>w <span style='color:#d2cd86; '>-</span> $surface<span style='color:#d2cd86; '>-></span>w <span style='color:#d2cd86; '>)</span> <span style='color:#d2cd86; '>/</span> <span style='color:#00a800; '>2</span><span style='color:#d2cd86; '>,</span> <span style='color:#d2cd86; '>(</span> $app<span style='color:#d2cd86; '>-></span>h <span style='color:#d2cd86; '>-</span> $surface<span style='color:#d2cd86; '>-></span>h <span style='color:#d2cd86; '>)</span> <span style='color:#d2cd86; '>/</span> <span style='color:#00a800; '>2</span><span style='color:#d2cd86; '>,</span> $app<span style='color:#d2cd86; '>-></span>w<span style='color:#d2cd86; '>,</span> $app<span style='color:#d2cd86; '>-></span>h <span style='color:#d2cd86; '>)</span>
+       <span style='color:#d2cd86; '>)</span><span style='color:#b060b0; '>;</span>
+ 
+    <span style='color:#e66170; font-weight:bold; '>die</span> <span style='color:#00c4c4; '>"Could not blit: "</span> <span style='color:#d2cd86; '>.</span> <span style='color:#904050; '>SDL</span><span style='color:#d2cd86; '>::</span><span style='color:#904050; '>get_error</span><span style='color:#d2cd86; '>(</span><span style='color:#d2cd86; '>)</span> <span style='color:#e66170; font-weight:bold; '>if</span> <span style='color:#d2cd86; '>(</span> $b <span style='color:#d2cd86; '>=</span><span style='color:#d2cd86; '>=</span> <span style='color:#d2cd86; '>-</span><span style='color:#00a800; '>1</span> <span style='color:#d2cd86; '>)</span><span style='color:#b060b0; '>;</span>
+</pre><br />
+If the error message is 'Blit combination not supported' that means that the BPP is incorrect or incosistent with the dimensions. After that a simple update_rect will so your new surface on the screen.<div class="blogger-post-footer"><img width='1' height='1' src='https://blogger.googleusercontent.com/tracker/3102167581424744259-3580429408870545769?l=yapgh.blogspot.com' alt='' /></div>
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