Amateur Astronomie

AA

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var p = brd.create('point', [0,0]); var q = brd.create('point', [3,3]); var circ = brd.create('circle', [p, q]);

Create an empty curve var ticks = brd.create('curve', 0], [0, {strokeWidth: 1, strokeColor: 'blue', strokeOpacity: 0.5}); Make ticks out of the curve ticks.updateDataArray = function() {

  var cx = circ.center.X(),
      cy = circ.center.Y(),
      r = circ.Radius(),
      i, 
      ticklen = 0.3,           // Length of ticks in user space coordinates
      steps = 20,              // Number of ticks
      d = ticklen * 0.5,
      alpha = 2 * Math.PI / steps;

  this.dataX = [];
  this.dataY = [];
  for (i = 0; i < steps; i++) {
      // Start of a tick
      this.dataX.push( cx + (r - d)* Math.cos(i * alpha) );
      this.dataY.push( cy + (r - d) * Math.sin(i * alpha) );
      // End of tick
      this.dataX.push( cx + (r + d) * Math.cos(i * alpha) );
      this.dataY.push( cy + (r + d) * Math.sin(i * alpha) );
      // Interrupt the curve
      this.dataX.push( NaN );
      this.dataY.push( NaN );
  }

}; brd.update();

</script>

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