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-HackFest: Results
+SDL RC 2.5 decides to play with PDL
</h1>
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-<div style="text-align: right;"><i>The beautiful sunset,</i><br /></div><div style="text-align: right;"><i>is no match for,</i><br /></div><div style="text-align: right;"><i>the ugly sunrise<br /></i><br /></div><h1>Results</h1>On Sunday we had a hackfest on #sdl irc.perl.org. This is what we got done.<br /><br /><div class="separator" style="clear: both; text-align: center;"><a href="http://4.bp.blogspot.com/_NnqjAQEn1Xo/SsEsVovCs8I/AAAAAAAAABw/5wMJtyamCpo/s1600-h/sdl-tetris-osx.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://4.bp.blogspot.com/_NnqjAQEn1Xo/SsEsVovCs8I/AAAAAAAAABw/5wMJtyamCpo/s320/sdl-tetris-osx.png" /></a><br /></div><br /><br /><ol><li>MacOSX build is working again. It's still rough but Tetris works on it now. dngor++</li><li><a href="http://search.cpan.org/%7Ekthakore/SDL-Tutorial-Tetris-0.015/">SDL::Tutorial::Tetris</a> is on CPAN as v0.15. nferraz++</li><li><a href="http://github.com/m4gnet/SDL_perl/commit/9957e76f888ac71a911e3a71c2783141748d2387">SDL Perl docs</a> are a little better now. magnet++</li><li>Finally experimental <a href="http://github.com/kthakore/SDL_perl/tree/experimental">Rect and Game::Rect</a> are behaving. There is still more work needed in Game::Rect. Moreover there are more tests on the experimental release. garu++</li><li>Also POGL is <a href="http://sdlperl.pastebin.com/f78b8c1b9">working</a> experimentally with SDL. <br /></li></ol>Hopefully I can get the first three results into the next release soon. The next release 2.2.3 will go up as a developmental release first. Also the experimental branch is going up as version 2_4.<br /><br /><h1>Developers</h1>All developers please tell me what to put you guys want to be put down as on the <br />in the Docs for the SDL Perl Team section.<br /><br />--yapgh<div class="blogger-post-footer"><img width='1' height='1' src='https://blogger.googleusercontent.com/tracker/3102167581424744259-8724981068699019715?l=yapgh.blogspot.com' alt='' /></div></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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