Hintergrund Spiralen
====================
ScriptBegin
var Grafik = "Script Funktionen";

var n    =36;        // Teilung
    w    =360/n;     // Winkel
    Back ="red"
    Fill ="cyan"
    alpha=180;    // Transparenz 0-255

    min = 0.2;   // t Minimum
    max = 10;    // t Maximum
    dt  = 1;     // dt Schritt


var a=1.5; var b = 0.5;
function fx(u){ return a*Math.exp(b*u)*Math.cos(u);}
function fy(u){ return a*Math.exp(b*u)*Math.sin(u);}



function init()
{ t.setBrush(Back); t.setPen("",0,0);
  t.setPage();
  t.setAntiAliasing();
}

function draw()
{ //t.drawKoordSystem();
  //t.drawRaster();  
  t.goTo(0,0); t.turnTo(90);
 
  t.setNoStyle();
  t.beginPolygon();
  t.drawGraf("fx","fy");
  t.endPolygon(3);

  t.defDraw("LogBand");

  t.setPolygon(-1,-1);
  t.setRotate(w); t.addPolygon("LogBand");
  t.endPolygon(0);
  t.setPen("",0,0); t.setBrush(Fill,1,alpha);
  t.defDraw("LogBand");
  t.setIdentity();

  t.setScale(-1,1); t.setPolygon("LogBand");
  t.defDraw("LogBand1");
   
  t.goTo(0,0); 
  for (d=0; d<(360); d=d+2*w)
  { t.turnTo(d); 
    t.draw("LogBand"); t.draw("LogBand1");
  }
  
}
ScriptEnd#SpiraleLog
