Help/BinaryOps/atan2.html

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  24 <p class="p1"><b>atan2<span class="Apple-tab-span">     </span><span class="Apple-tab-span">    </span>arctangent</b></p>
  25 <p class="p2"><br></p>
  26 <p class="p3"><b>BinaryOperator</b></p>
  27 <p class="p2"><br></p>
  28 <p class="p3"><b>atan2(y, x)</b></p>
  29 <p class="p3"><b>y atan2: x</b></p>
  30 <p class="p3"><b>y.atan2(x)</b></p>
  31 <p class="p4"><br></p>
  32 <p class="p3">Returns the arctangent of y/x.</p>
  33 <p class="p2"><br></p>
  34 <p class="p3">See also <b>hypot</b>.</p>
  35 <p class="p2"><br></p>
  36 <p class="p3">OK, now we can add a pan to the <b>hypot</b> doppler examples by using atan2 to find the azimuth,<span class="Apple-converted-space"> </span></p>
  37 <p class="p3">or direction angle, of the sound source.</p>
  38 <p class="p3">Assume speakers at +/- 45 degrees and clip the direction to between those.</p>
  39 <p class="p4"><br></p>
  40 <p class="p5">(</p>
  41 <p class="p5">{</p>
  42 <p class="p5"><span class="Apple-tab-span">     </span><span class="s1">var</span> x, y, distance, velocity, pitchRatio, amplitude, azimuth, panValue;</p>
  43 <p class="p6"><span class="s2"><span class="Apple-tab-span">    </span></span>// object travels 200 meters in 6 secs (=120kph) passing 10 meters<span class="Apple-converted-space"> </span></p>
  44 <p class="p6"><span class="s2"><span class="Apple-tab-span">    </span></span>// from the listener</p>
  45 <p class="p5"><span class="Apple-tab-span">     </span>x = 10;</p>
  46 <p class="p5"><span class="Apple-tab-span">     </span>y = <span class="s1">LFSaw</span>.kr(1/6, 0, 100);</p>
  47 <p class="p5"><span class="Apple-tab-span">     </span>distance = hypot(x, y);</p>
  48 <p class="p5"><span class="Apple-tab-span">     </span>velocity = <span class="s1">Slope</span>.kr(distance);</p>
  49 <p class="p5"><span class="Apple-tab-span">     </span>pitchRatio = (344 - velocity) / 344;<span class="Apple-converted-space">  </span><span class="s3">// speed of sound is 344 meters/sec</span></p>
  50 <p class="p5"><span class="Apple-tab-span">     </span>amplitude = 10 / distance.squared;</p>
  51 <p class="p5"><span class="Apple-tab-span">     </span>azimuth = atan2(y, x); <span class="s3">// azimuth in radians</span></p>
  52 <p class="p5"><span class="Apple-tab-span">     </span>panValue = (azimuth / 0.5pi).clip2(1);</p>
  53 <p class="p5"><span class="Apple-tab-span">     </span><span class="s1">Pan2</span>.ar(<span class="s1">FSinOsc</span>.ar(1000 * pitchRatio), panValue, amplitude)</p>
  54 <p class="p5">}.play)</p>
  55 <p class="p7"><br></p>
  56 <p class="p5">(</p>
  57 <p class="p5">{</p>
  58 <p class="p5"><span class="Apple-tab-span">     </span><span class="s1">var</span> x, y, distance, velocity, pitchRatio, amplitude, motorSound,<span class="Apple-converted-space"> </span></p>
  59 <p class="p5"><span class="Apple-tab-span">     </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>azimuth, panValue;</p>
  60 <p class="p6"><span class="s2"><span class="Apple-tab-span">    </span></span>// object travels 200 meters in 6 secs (=120kph) passing 10 meters<span class="Apple-converted-space"> </span></p>
  61 <p class="p6"><span class="s2"><span class="Apple-tab-span">    </span></span>// from the listener</p>
  62 <p class="p5"><span class="Apple-tab-span">     </span>x = 10;</p>
  63 <p class="p5"><span class="Apple-tab-span">     </span>y = <span class="s1">LFSaw</span>.kr(1/6, 0, 100);</p>
  64 <p class="p5"><span class="Apple-tab-span">     </span>distance = hypot(x, y);</p>
  65 <p class="p5"><span class="Apple-tab-span">     </span>amplitude = 40 / distance.squared;</p>
  66 <p class="p5"><span class="Apple-tab-span">     </span>motorSound = <span class="s1">RLPF</span>.ar(<span class="s1">FSinOsc</span>.ar(200, 0, <span class="s1">LFPulse</span>.ar(31.3, 0, 0.4)), 400, 0.3);</p>
  67 <p class="p5"><span class="Apple-tab-span">     </span>azimuth = atan2(y, x); <span class="s3">// azimuth in radians</span></p>
  68 <p class="p5"><span class="Apple-tab-span">     </span>panValue = (azimuth / 0.5pi).clip2(1); <span class="s3">// make a value for Pan2 from azimuth</span></p>
  69 <p class="p5"><span class="Apple-tab-span">     </span><span class="s1">Pan2</span>.ar(<span class="s1">DelayL</span>.ar(motorSound, 110/344, distance/344), panValue, amplitude)</p>
  70 <p class="p5">}.play)</p>
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