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[sdlgit/SDL-Site.git] / pages / blog-0005.html-inc

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 <div class="blog">
 <h1 id="NAME">
-Once in a while .... (set_event_filter)
+SDL RC 2.5 decides to play with PDL
 </h1>
 <div class="CONTENT">
-<div style="text-align: right;"><i> <br />Once in a while <br />Things just work! <br /></i><br /></div><br /><br />So I have been hacking for a while on SDL::Events::set_event_filter. The code below is an example usage. The magic behind this is <a href="http://github.com/kthakore/SDL_perl/blob/1712fe42d62c2a3e382e6bf91366eb2ce9d2f5f4/src/Core/Events.xs">here</a> <br /><br /><pre><a href="" name="line1"> 1</a> <span style="color: #444444;">#!/usr/bin/perl -w<br /><a href="" name="line2"> 2</a> </span><b>use</b> strict;<br /><a href="" name="line3"> 3</a> <b>use</b> warnings;<br /><a href="" name="line4"> 4</a> <b>use</b> SDL v2.3; <span style="color: #444444;">#Require the redesign branch<br /><a href="" name="line5"> 5</a> </span><b>use</b> SDL::Video;<br /><a href="" name="line6"> 6</a> <b>use</b> SDL::Event;<br /><a href="" name="line7"> 7</a> <b>use</b> SDL::Events;<br /><a href="" name="line8"> 8</a> <br /><a href="" name="line9"> 9</a> SDL::init<span style="color: #4444ff;"><b>(</b></span>SDL_INIT_VIDEO<span style="color: #4444ff;"><b>)</b></span>;<br /><a href="" name="line10">10</a> <b>my</b> <span style="color: #2040a0;">$display</span> = SDL::Video::set_video_mode<span style="color: #4444ff;"><b>(</b></span>640,480,32, SDL_SWSURFACE <span style="color: #4444ff;"><b>)</b></span>;<br /><a href="" name="line11">11</a> <b>my</b>  <span style="color: #2040a0;">$event</span> = SDL::Event-&gt;<b>new</b><span style="color: #4444ff;"><b>(</b></span><span style="color: #4444ff;"><b>)</b></span>;<br /><a href="" name="line12">12</a> <br /><a href="" name="line13">13</a> <span style="color: #444444;">#This filters out all ActiveEvents<br /><a href="" name="line14">14</a> </span><b>my</b> <span style="color: #2040a0;">$filter</span> = sub <span style="color: #4444ff;"><b>{</b></span> <br /><a href="" name="line15">15</a>      <b>my</b> <span style="color: #4444ff;"><b>(</b></span><span style="color: #2040a0;">$e</span>, <span style="color: #2040a0;">$type</span><span style="color: #4444ff;"><b>)</b></span> = <span style="color: #4444ff;"><b>(</b></span><span style="color: #2040a0;">$_</span><span style="color: #4444ff;"><b>[</b></span>0<span style="color: #4444ff;"><b>]</b></span>, <span style="color: #2040a0;">$_</span><span style="color: #4444ff;"><b>[</b></span>0<span style="color: #4444ff;"><b>]</b></span>-&gt;type<span style="color: #4444ff;"><b>)</b></span>; <br /><a href="" name="line16">16</a>      <b>if</b><span style="color: #4444ff;"><b>(</b></span><span style="color: #2040a0;">$type</span> == SDL_ACTIVEEVENT<span style="color: #4444ff;"><b>)</b></span><span style="color: #4444ff;"><b>{</b></span> <b>return</b> 0 <span style="color: #4444ff;"><b>}</b></span> <br /><a href="" name="line17">17</a>      <b>elsif</b><span style="color: #4444ff;"><b>(</b></span><span style="color: #2040a0;">$type</span> == SDL_MOUSEBUTTONDOWN &amp;&amp; <span style="color: #2040a0;">$e</span>-&gt;button_button == 1<span style="color: #4444ff;"><b>)</b></span><span style="color: #4444ff;"><b>{</b></span> <b>return</b> 0 <span style="color: #4444ff;"><b>}</b></span><br /><a href="" name="line18">18</a>      <b>else</b> <span style="color: #4444ff;"><b>{</b></span> <b>return</b> 1; <span style="color: #4444ff;"><b>}</b></span><br /><a href="" name="line19">19</a>       <span style="color: #4444ff;"><b>}</b></span>;<br /><a href="" name="line20">20</a> <br /><a href="" name="line21">21</a> SDL::Events::set_event_filter<span style="color: #4444ff;"><b>(</b></span><span style="color: #2040a0;">$filter</span><span style="color: #4444ff;"><b>)</b></span>;<br /><a href="" name="line22">22</a> <br /><a href="" name="line23">23</a> <b>while</b><span style="color: #4444ff;"><b>(</b></span>1<span style="color: #4444ff;"><b>)</b></span><br /><a href="" name="line24">24</a> <span style="color: #4444ff;"><b>{</b></span><br /><a href="" name="line25">25</a> <br /><a href="" name="line26">26</a>   SDL::Events::pump_events<span style="color: #4444ff;"><b>(</b></span><span style="color: #4444ff;"><b>)</b></span>;<br /><a href="" name="line27">27</a>   <b>if</b><span style="color: #4444ff;"><b>(</b></span>SDL::Events::poll_event<span style="color: #4444ff;"><b>(</b></span><span style="color: #2040a0;">$event</span><span style="color: #4444ff;"><b>)</b></span><span style="color: #4444ff;"><b>)</b></span><br /><a href="" name="line28">28</a>   <span style="color: #4444ff;"><b>{</b></span><br /><a href="" name="line29">29</a> <br /><a href="" name="line30">30</a>   <b>if</b><span style="color: #4444ff;"><b>(</b></span>  <span style="color: #2040a0;">$event</span>-&gt;type == SDL_ACTIVEEVENT<span style="color: #4444ff;"><b>)</b></span><br /><a href="" name="line31">31</a>  <span style="color: #4444ff;"><b>{</b></span><br /><a href="" name="line32">32</a>  <span style="color: brown;"><b>print</b></span> <span style="color: green;">"Hello Mouse!!!<span style="color: #77dd77;">\n</span>"</span> <b>if</b> <span style="color: #4444ff;"><b>(</b></span><span style="color: #2040a0;">$event</span>-&gt;active_gain &amp;&amp; <span style="color: #4444ff;"><b>(</b></span><span style="color: #2040a0;">$event</span>-&gt;active_state == SDL_APPMOUSEFOCUS<span style="color: #4444ff;"><b>)</b></span> <span style="color: #4444ff;"><b>)</b></span>;<br /><a href="" name="line33">33</a>  <span style="color: brown;"><b>print</b></span> <span style="color: green;">"Bye Mouse!!!<span style="color: #77dd77;">\n</span>"</span> <b>if</b> <span style="color: #4444ff;"><b>(</b></span>!<span style="color: #2040a0;">$event</span>-&gt;active_gain &amp;&amp; <span style="color: #4444ff;"><b>(</b></span><span style="color: #2040a0;">$event</span>-&gt;active_state == SDL_APPMOUSEFOCUS<span style="color: #4444ff;"><b>)</b></span> <span style="color: #4444ff;"><b>)</b></span>;<br /><a href="" name="line34">34</a>         <span style="color: #4444ff;"><b>}</b></span><br /><a href="" name="line35">35</a>   <b>if</b><span style="color: #4444ff;"><b>(</b></span> <span style="color: #2040a0;">$event</span>-&gt;type == SDL_MOUSEBUTTONDOWN<span style="color: #4444ff;"><b>)</b></span><br /><a href="" name="line36">36</a>    <span style="color: #4444ff;"><b>{</b></span><br /><a href="" name="line37">37</a>  <b>my</b> <span style="color: #4444ff;"><b>(</b></span><span style="color: #2040a0;">$x</span>, <span style="color: #2040a0;">$y</span>, <span style="color: #2040a0;">$but</span> <span style="color: #4444ff;"><b>)</b></span> = <span style="color: #4444ff;"><b>(</b></span><span style="color: #2040a0;">$event</span>-&gt;button_x, <span style="color: #2040a0;">$event</span>-&gt;button_y, <span style="color: #2040a0;">$event</span>-&gt;button_button<span style="color: #4444ff;"><b>)</b></span>;<br /><a href="" name="line38">38</a>  <span style="color: brown;"><b>warn</b></span> <span style="color: green;">"<span style="color: #2040a0;">$but</span> CLICK!!! at <span style="color: #2040a0;">$x</span> and <span style="color: #2040a0;">$y</span> <span style="color: #77dd77;">\n</span>"</span>;<br /><a href="" name="line39">39</a>  <span style="color: #4444ff;"><b>}</b></span><br /><a href="" name="line40">40</a> <br /><a href="" name="line41">41</a>       <b>last</b> <b>if</b><span style="color: #4444ff;"><b>(</b></span><span style="color: #2040a0;">$event</span>-&gt;type == SDL_QUIT<span style="color: #4444ff;"><b>)</b></span>;<br /><a href="" name="line42">42</a>   <span style="color: #4444ff;"><b>}</b></span><br /><a href="" name="line43">43</a> <span style="color: #4444ff;"><b>}</b></span><br /><a href="" name="line44">44</a> SDL::quit<span style="color: #4444ff;"><b>(</b></span><span style="color: #4444ff;"><b>)</b></span>;&nbsp;</pre><pre>&nbsp;</pre><pre>&nbsp;</pre><pre>Tinker with $filter and look at perldoc lib/SDL/pods/Event.pod.&nbsp;</pre><pre>&nbsp;</pre><pre>Have fun,</pre><pre>--yapgh</pre><div class="blogger-post-footer"><img width='1' height='1' src='https://blogger.googleusercontent.com/tracker/3102167581424744259-2301663122914111362?l=yapgh.blogspot.com' alt='' /></div></div></div>
\ No newline at end of file
+<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>
+<p><a href="http://feedads.g.doubleclick.net/~a/HRpCokqdJ-wzrP1ZXUvgwcUNL_s/0/da"><img src="http://feedads.g.doubleclick.net/~a/HRpCokqdJ-wzrP1ZXUvgwcUNL_s/0/di" border="0" ismap="true"></img></a><br/>
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