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		<title>Timing and Bitmap Troubles</title>
		<link>http://www.allegro.cc/forums/view/610349</link>
		<description>Allegro.cc Forum Thread</description>
		<webMaster>matthew@allegro.cc (Matthew Leverton)</webMaster>
		<lastBuildDate>Sat, 02 Jun 2012 14:41:06 +0000</lastBuildDate>
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		<description><![CDATA[<div class="mockup v2"><p><b>sigh</b><img src="http://www.allegro.cc/forums/smileys/cry.gif" alt=":&#39;(" /></p><p>Been fiddling with my timers and main loop with regards to the timers and now have a loop which boils down to:
</p><div class="source-code"><div class="toolbar"><span class="button numbers"><b>#</b></span><span class="button select">Select</span><span class="button expand">Expand</span></div><div class="inner"><span class="number">   1</span><span class="k1">while</span><span class="k2">(</span><span class="k3">!</span>doExit<span class="k2">)</span>
<span class="number">   2</span>  <span class="k2">{</span>
<span class="number">   3</span>    <span class="c">//test for an event</span>
<span class="number">   4</span>    <span class="k1">bool</span> get_event <span class="k3">=</span> <a href="http://www.allegro.cc/manual/al_wait_for_event_until"><span class="a">al_wait_for_event_until</span></a><span class="k2">(</span>event_queue, <span class="k3">&amp;</span>ev, <span class="k3">&amp;</span>timeout<span class="k2">)</span><span class="k2">;</span>
<span class="number">   5</span>
<span class="number">   6</span>    <span class="c">//trigger a redraw or update</span>
<span class="number">   7</span>    <span class="k1">if</span><span class="k2">(</span>ev.type <span class="k3">=</span><span class="k3">=</span> ALLEGRO_EVENT_TIMER<span class="k2">)</span>
<span class="number">   8</span>    <span class="k2">{</span>
<span class="number">   9</span>      <span class="k1">if</span><span class="k2">(</span>ev.timer.source <span class="k3">=</span><span class="k3">=</span> animTimer<span class="k2">)</span>
<span class="number">  10</span>      <span class="k2">{</span>
<span class="number">  11</span>        redraw <span class="k3">=</span> <span class="k1">true</span><span class="k2">;</span>
<span class="number">  12</span>      <span class="k2">}</span>
<span class="number">  13</span>      <span class="k1">else</span> <span class="k1">if</span><span class="k2">(</span>ev.timer.source <span class="k3">=</span><span class="k3">=</span> updateTimer<span class="k2">)</span>
<span class="number">  14</span>      <span class="k2">{</span>
<span class="number">  15</span>        update <span class="k3">=</span> <span class="k1">true</span><span class="k2">;</span>
<span class="number">  16</span>      <span class="k2">}</span>
<span class="number">  17</span>    <span class="k2">}</span><span class="k1">else</span> <span class="k1">if</span><span class="k2">(</span>ev.type <span class="k3">=</span><span class="k3">=</span> ALLEGRO_EVENT_DISPLAY_CLOSE<span class="k2">)</span> <span class="k2">{</span>
<span class="number">  18</span>      <span class="k1">break</span><span class="k2">;</span>
<span class="number">  19</span>    <span class="k2">}</span><span class="k1">else</span> <span class="k1">if</span><span class="k2">(</span>ev.type <span class="k3">=</span><span class="k3">=</span> ALLEGRO_EVENT_KEY_DOWN<span class="k2">)</span>
<span class="number">  20</span>    <span class="k2">{</span>
<span class="number">  21</span>         <span class="k1">switch</span><span class="k2">(</span>ev.keyboard.keycode<span class="k2">)</span> <span class="k2">{</span>
<span class="number">  22</span>            <span class="k1">case</span> ALLEGRO_KEY_UP:
<span class="number">  23</span>              <a href="http://www.allegro.cc/manual/key"><span class="a">key</span></a><span class="k2">[</span>KEY_UP<span class="k2">]</span> <span class="k3">=</span> <span class="k1">true</span><span class="k2">;</span>
<span class="number">  24</span>              <span class="k1">break</span><span class="k2">;</span>
<span class="number">  25</span>            <span class="k1">case</span> ALLEGRO_KEY_DOWN:
<span class="number">  26</span>              <a href="http://www.allegro.cc/manual/key"><span class="a">key</span></a><span class="k2">[</span>KEY_DOWN<span class="k2">]</span> <span class="k3">=</span> <span class="k1">true</span><span class="k2">;</span>
<span class="number">  27</span>              <span class="k1">break</span><span class="k2">;</span>
<span class="number">  28</span>            <span class="k1">case</span> ALLEGRO_KEY_LEFT:
<span class="number">  29</span>              <a href="http://www.allegro.cc/manual/key"><span class="a">key</span></a><span class="k2">[</span>KEY_LEFT<span class="k2">]</span> <span class="k3">=</span> <span class="k1">true</span><span class="k2">;</span>
<span class="number">  30</span>              <span class="k1">break</span><span class="k2">;</span>
<span class="number">  31</span>            <span class="k1">case</span> ALLEGRO_KEY_RIGHT:
<span class="number">  32</span>              <a href="http://www.allegro.cc/manual/key"><span class="a">key</span></a><span class="k2">[</span>KEY_RIGHT<span class="k2">]</span> <span class="k3">=</span> <span class="k1">true</span><span class="k2">;</span>
<span class="number">  33</span>              <span class="k1">break</span><span class="k2">;</span>
<span class="number">  34</span>            <span class="k1">case</span> ALLEGRO_KEY_1:
<span class="number">  35</span>              player.playerSpeed <span class="k3">+</span><span class="k3">=</span> <span class="n">0</span>.<span class="n">1</span><span class="k2">;</span> <span class="c">//purely for testing</span>
<span class="number">  36</span>              <span class="k1">break</span><span class="k2">;</span>
<span class="number">  37</span>            <span class="k1">case</span> ALLEGRO_KEY_2:
<span class="number">  38</span>              player.playerSpeed <span class="k3">-</span><span class="k3">=</span> <span class="n">0</span>.<span class="n">1</span><span class="k2">;</span> <span class="c">//purely for testing</span>
<span class="number">  39</span>              <span class="k1">break</span><span class="k2">;</span>
<span class="number">  40</span>         <span class="k2">}</span>
<span class="number">  41</span>
<span class="number">  42</span>    <span class="k2">}</span><span class="k1">else</span> <span class="k1">if</span><span class="k2">(</span>ev.type <span class="k3">=</span><span class="k3">=</span> ALLEGRO_EVENT_KEY_UP<span class="k2">)</span>
<span class="number">  43</span>    <span class="k2">{</span>
<span class="number">  44</span>      <span class="c">//test if a key has been released</span>
<span class="number">  45</span>         <span class="k1">switch</span><span class="k2">(</span>ev.keyboard.keycode<span class="k2">)</span> <span class="k2">{</span>
<span class="number">  46</span>            <span class="k1">case</span> ALLEGRO_KEY_UP:
<span class="number">  47</span>               <a href="http://www.allegro.cc/manual/key"><span class="a">key</span></a><span class="k2">[</span>KEY_UP<span class="k2">]</span> <span class="k3">=</span> <span class="k1">false</span><span class="k2">;</span>
<span class="number">  48</span>               <span class="k1">break</span><span class="k2">;</span>
<span class="number">  49</span>
<span class="number">  50</span>            <span class="k1">case</span> ALLEGRO_KEY_DOWN:
<span class="number">  51</span>               <a href="http://www.allegro.cc/manual/key"><span class="a">key</span></a><span class="k2">[</span>KEY_DOWN<span class="k2">]</span> <span class="k3">=</span> <span class="k1">false</span><span class="k2">;</span>
<span class="number">  52</span>               <span class="k1">break</span><span class="k2">;</span>
<span class="number">  53</span>
<span class="number">  54</span>            <span class="k1">case</span> ALLEGRO_KEY_LEFT:
<span class="number">  55</span>               <a href="http://www.allegro.cc/manual/key"><span class="a">key</span></a><span class="k2">[</span>KEY_LEFT<span class="k2">]</span> <span class="k3">=</span> <span class="k1">false</span><span class="k2">;</span>
<span class="number">  56</span>               <span class="k1">break</span><span class="k2">;</span>
<span class="number">  57</span>
<span class="number">  58</span>            <span class="k1">case</span> ALLEGRO_KEY_RIGHT:
<span class="number">  59</span>               <a href="http://www.allegro.cc/manual/key"><span class="a">key</span></a><span class="k2">[</span>KEY_RIGHT<span class="k2">]</span> <span class="k3">=</span> <span class="k1">false</span><span class="k2">;</span>
<span class="number">  60</span>               <span class="k1">break</span><span class="k2">;</span>
<span class="number">  61</span>
<span class="number">  62</span>            <span class="k1">case</span> ALLEGRO_KEY_ESCAPE:
<span class="number">  63</span>               doExit <span class="k3">=</span> <span class="k1">true</span><span class="k2">;</span>
<span class="number">  64</span>               <span class="k1">break</span><span class="k2">;</span>
<span class="number">  65</span>        <span class="k2">}</span>
<span class="number">  66</span>    <span class="k2">}</span>
<span class="number">  67</span>
<span class="number">  68</span>    <span class="c">//game logic</span>
<span class="number">  69</span>    <span class="k1">if</span><span class="k2">(</span><a href="http://www.allegro.cc/manual/al_is_event_queue_empty"><span class="a">al_is_event_queue_empty</span></a><span class="k2">(</span>event_queue<span class="k2">)</span> <span class="k3">&amp;</span><span class="k3">&amp;</span> update<span class="k2">)</span><span class="k2">{</span>
<span class="number">  70</span>      player.update<span class="k2">(</span><a href="http://www.allegro.cc/manual/key"><span class="a">key</span></a><span class="k2">)</span><span class="k2">;</span> <span class="c">//tells the player what key has been pressed</span>
<span class="number">  71</span>
<span class="number">  72</span>      <span class="c">//will they hit something if they move using this key?</span>
<span class="number">  73</span>      <span class="k1">if</span><span class="k2">(</span>playerBGCollision<span class="k2">(</span>player<span class="k2">)</span><span class="k2">)</span><span class="k2">{</span>
<span class="number">  74</span>          player.hasCollided<span class="k2">(</span><span class="k2">)</span><span class="k2">;</span> <span class="c">//if so make them stand still (i.e. velocity == 0)</span>
<span class="number">  75</span>      <span class="k2">}</span>
<span class="number">  76</span>
<span class="number">  77</span>      player.move<span class="k2">(</span><span class="k2">)</span><span class="k2">;</span>   <span class="c">//update position variables</span>
<span class="number">  78</span>      update <span class="k3">=</span> <span class="k1">false</span><span class="k2">;</span>
<span class="number">  79</span>    <span class="k2">}</span>
<span class="number">  80</span>
<span class="number">  81</span>    <span class="c">//drawing</span>
<span class="number">  82</span>    <span class="k1">if</span><span class="k2">(</span><a href="http://www.allegro.cc/manual/al_is_event_queue_empty"><span class="a">al_is_event_queue_empty</span></a><span class="k2">(</span>event_queue<span class="k2">)</span> <span class="k3">&amp;</span><span class="k3">&amp;</span> redraw<span class="k2">)</span> <span class="k2">{</span>
<span class="number">  83</span>
<span class="number">  84</span>      <a href="http://www.allegro.cc/manual/al_clear_to_color"><span class="a">al_clear_to_color</span></a><span class="k2">(</span><a href="http://www.allegro.cc/manual/al_map_rgb"><span class="a">al_map_rgb</span></a><span class="k2">(</span><span class="n">0</span>,<span class="n">0</span>,<span class="n">0</span><span class="k2">)</span><span class="k2">)</span><span class="k2">;</span>              <span class="c">//clear</span>
<span class="number">  85</span>      MapDrawBG<span class="k2">(</span>plotMapx,plotMapy,<span class="n">0</span>,<span class="n">0</span>,SWIDTH,SHEIGHT<span class="k2">)</span><span class="k2">;</span>
<span class="number">  86</span>      player.plot<span class="k2">(</span>plotMapx, plotMapy<span class="k2">)</span><span class="k2">;</span>
<span class="number">  87</span>      MapDrawFG<span class="k2">(</span>plotMapx,plotMapy,<span class="n">0</span>,<span class="n">0</span>,SWIDTH,SHEIGHT,<span class="n">0</span><span class="k2">)</span><span class="k2">;</span>
<span class="number">  88</span>
<span class="number">  89</span>      <a href="http://www.allegro.cc/manual/al_flip_display"><span class="a">al_flip_display</span></a><span class="k2">(</span><span class="k2">)</span><span class="k2">;</span>
<span class="number">  90</span>
<span class="number">  91</span>      redraw <span class="k3">=</span> <span class="k1">false</span><span class="k2">;</span>
<span class="number">  92</span>    <span class="k2">}</span>
<span class="number">  93</span>
<span class="number">  94</span>  <span class="k2">}</span>
<span class="number">  95</span>  <a href="http://www.allegro.cc/manual/al_destroy_display"><span class="a">al_destroy_display</span></a><span class="k2">(</span>display<span class="k2">)</span><span class="k2">;</span>
<span class="number">  96</span>  <a href="http://www.allegro.cc/manual/al_destroy_event_queue"><span class="a">al_destroy_event_queue</span></a><span class="k2">(</span>event_queue<span class="k2">)</span><span class="k2">;</span>
<span class="number">  97</span>  <span class="k1">return</span> <span class="n">0</span><span class="k2">;</span>
<span class="number">  98</span><span class="k2">}</span><span class="k2">;</span>
</div></div><p>

From reading forums this was said to be the recommended way of carrying out the game loop (if you haven&#39;t noticed it is also based on the Allegro 5 tutorials).  But for some reason there is a lag in the timing (speeds up and down), not big, but noticeable. Plus the screen flickers slightly as it scrolls.</p><p>I thought that this would be down to loading memory bitmaps rather than video bitmaps. But they are only a few 100kB!  I loaded the bitmaps for the player sprite AFTER I created the display anyway to make them video but to no avail.  I checked the flags of the bitmaps and they came out with a flag that I couldn&#39;t identify.</p><p>So...
</p><ul><li><p>Is there something wrong with my loop?</p></li><li><p>Why would my bitmaps say they have a flag of int value 1056 when I check? What type of bitmaps are they?</p></li></ul><p> <img src="http://www.allegro.cc/forums/smileys/huh.gif" alt="???" />
</p></div>]]>
		</description>
		<author>no-reply@allegro.cc (oobtim)</author>
		<pubDate>Sat, 02 Jun 2012 02:10:16 +0000</pubDate>
	</item>
	<item>
		<description><![CDATA[<div class="mockup v2"><p>Flags are stored bitwise<br />You must use something along these lines:
</p><div class="source-code snippet"><div class="inner"><pre><span class="k1">if</span> <span class="k2">(</span>myFlags <span class="k3">&amp;</span> FLAG_SOME_FLAG<span class="k2">)</span>
<span class="k2">{</span>
    <span class="c">// Flag is enabled</span>
<span class="k2">}</span>
</pre></div></div><p>
</p></div>]]>
		</description>
		<author>no-reply@allegro.cc (l j)</author>
		<pubDate>Sat, 02 Jun 2012 02:13:03 +0000</pubDate>
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	<item>
		<description><![CDATA[<div class="mockup v2"><p>Thank you, that sorts out whether I have video/memory bitmaps <img src="http://www.allegro.cc/forums/smileys/cheesy.gif" alt=":D" /></p><p>Anything wrong with my loop though, as the glitch still remains?:-/</p><p>Is there something wrong with the way the updates and redraws are called? Updates and redraws are done 60 times a second and I have a separate timer for each.</p><p><b>EDIT</b></p><p>Sorted it <img src="http://www.allegro.cc/forums/smileys/cheesy.gif" alt=":D" />  Needed to use interpolation to get things running smoothly.  That&#39;ll teach me to code after a few beers <b>hic</b> <img src="http://www.allegro.cc/forums/smileys/embarassed.gif" alt=":-[" />
</p></div>]]>
		</description>
		<author>no-reply@allegro.cc (oobtim)</author>
		<pubDate>Sat, 02 Jun 2012 14:41:06 +0000</pubDate>
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