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Date: Wed, 13 May 2015 14:26:32 -0400
Message-Id: <201505131826.t4DIQWuQ002817@envy.delorie.com>
From: DJ Delorie <dj AT delorie DOT com>
To: geda-user AT delorie DOT com
In-reply-to: <1431541322.2827.46.camel@linetec> (geda-user@delorie.com)
Subject: Re: [geda-user] Free rotate and exported centroid (XY) file question
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Consider a part with 16 pins in a row (sip) but staggered
left-right-left-right etc.  Is the part rotated, or not?

The XY code in src/hid/bom.c rounds angles to multiples of 90 to avoid
being confused by such things.  I.e. it only works for parts that
haven't been free-rotated.

static double
xyToAngle (double x, double y, bool morethan2pins)
{
  double d = atan2 (-y, x) * 180.0 / M_PI;

  /* IPC 7351 defines different rules for 2 pin elements */
  if (morethan2pins)
    {
      /* Multi pin case:
       * Output 0 degrees if pin1 in is top left or top, i.e. between angles of
       * 80 to 170 degrees.
       * Pin #1 can be at dead top (e.g. certain PLCCs) or anywhere in the top
       * left.
       */	    
      if (d < -100)
        return 90; /* -180 to -100 */
      else if (d < -10)
        return 180; /* -100 to -10 */
      else if (d < 80)
        return 270; /* -10 to 80 */
      else if (d < 170)
        return 0; /* 80 to 170 */
      else
        return 90; /* 170 to 180 */
    }
  else
    {
      /* 2 pin element:
       * Output 0 degrees if pin #1 is in top left or left, i.e. in sector
       * between angles of 95 and 185 degrees.
       */
      if (d < -175)
        return 0; /* -180 to -175 */
      else if (d < -85)
        return 90; /* -175 to -85 */
      else if (d < 5)
        return 180; /* -85 to 5 */
      else if (d < 95)
        return 270; /* 5 to 95 */
      else
        return 0; /* 95 to 180 */
    }
}