Zig Zag Indicator

//+------------------------------------------------------------------+
//| Custom Moving Average.mq4 |
//| Copyright © 2005, MetaQuotes Software Corp. |
//| http://www.metaquotes.net/ |
//+------------------------------------------------------------------+
#property copyright "Copyright © 2005, MetaQuotes Software Corp."
#property link      "http://www.metaquotes.net/"

#property indicator_chart_window
#property indicator_buffers 1
#property indicator_color1 Red
//---- indicator parameters
extern int ExtDepth=12; extern int ExtDeviation=5; extern int ExtBackstep=3; //---- indicator buffers
double ExtMapBuffer[]; double ExtMapBuffer2[]; //+------------------------------------------------------------------+
//| Custom indicator initialization function |
//+------------------------------------------------------------------+
int init()
  {
   IndicatorBuffers(2); //---- drawing settings
   SetIndexStyle(0,DRAW_SECTION); //---- indicator buffers mapping
   SetIndexBuffer(0,ExtMapBuffer); SetIndexBuffer(1,ExtMapBuffer2); SetIndexEmptyValue(0,0.0); //---- indicator short name
   IndicatorShortName("ZigZag("+ExtDepth+","+ExtDeviation+","+ExtBackstep+")"); //---- initialization done
   return(0); }
//+------------------------------------------------------------------+
//| |
//+------------------------------------------------------------------+
int start()
  {
   int    shift, back,lasthighpos,lastlowpos; double val,res; double curlow,curhigh,lasthigh,lastlow; for(shift=Bars-ExtDepth; shift>=0; shift--)
     {
      val=Low[Lowest(NULL,0,MODE_LOW,ExtDepth,shift)]; if(val==lastlow) val=0.0; else
        {
         lastlow=val; if((Low[shift]-val)>(ExtDeviation*Point)) val=0.0; else
           {
            for(back=1; back<=ExtBackstep; back++)
              {
               res=ExtMapBuffer[shift+back]; if((res!=0)&&(res>val)) ExtMapBuffer[shift+back]=0.0; }
           }
        }
      ExtMapBuffer[shift]=val; //--- high
      val=High[Highest(NULL,0,MODE_HIGH,ExtDepth,shift)]; if(val==lasthigh) val=0.0; else
        {
         lasthigh=val; if((val-High[shift])>(ExtDeviation*Point)) val=0.0; else
           {
            for(back=1; back<=ExtBackstep; back++)
              {
               res=ExtMapBuffer2[shift+back]; if((res!=0)&&(res<val)) ExtMapBuffer2[shift+back]=0.0; }
           }
        }
      ExtMapBuffer2[shift]=val; }

   // final cutting
   lasthigh=-1; lasthighpos=-1; lastlow=-1; lastlowpos=-1; for(shift=Bars-ExtDepth; shift>=0; shift--)
     {
      curlow=ExtMapBuffer[shift]; curhigh=ExtMapBuffer2[shift]; if((curlow==0)&&(curhigh==0)) continue; //---
      if(curhigh!=0)
        {
         if(lasthigh>0)
           {
            if(lasthigh<curhigh) ExtMapBuffer2[lasthighpos]=0; else ExtMapBuffer2[shift]=0; }
         //---
         if(lasthigh<curhigh || lasthigh<0)
           {
            lasthigh=curhigh; lasthighpos=shift; }
         lastlow=-1; }
      //----
      if(curlow!=0)
        {
         if(lastlow>0)
           {
            if(lastlow>curlow) ExtMapBuffer[lastlowpos]=0; else ExtMapBuffer[shift]=0; }
         //---
         if((curlow<lastlow)||(lastlow<0))
           {
            lastlow=curlow; lastlowpos=shift; }
         lasthigh=-1; }
     }
 
   for(shift=Bars-1; shift>=0; shift--)
     {
      if(shift>=Bars-ExtDepth) ExtMapBuffer[shift]=0.0; else
        {
         res=ExtMapBuffer2[shift]; if(res!=0.0) ExtMapBuffer[shift]=res; }
     }
  }