//===========================================================================
//                             TRAVERSE
//
//    This program simulates laying out a traverse, leg by leg.  From a
//    starting point, one moves a given distance on a given bearing to a new
//    point (hub), and continues traversing a terrain from hub to hub.
//===========================================================================

#include <vcl.h>
#pragma hdrstop
#include <math.h>
#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
   : TForm(Owner)
{
}

//========================================================= DECLARE VARIABLES
float bearing, distance;
struct point {
   float x;
   float y;
} ;
point startPoint, oldPoint, newPoint;
float deltaBearing, deltaDistance;
int loops;

//======================================================= PLOT STARTING POINT
void plotStartingPoint (void) {
   Form1->Canvas->Brush->Color = clYellow;
   Form1->Canvas->Ellipse(oldPoint.x-3, oldPoint.y-3,
      oldPoint.x+3, oldPoint.y+3);
   Form1->Canvas->Brush->Color = clRed;
}

//================================================================ INITIALIZE
void initialize (void) {
   Form1->Canvas->Brush->Color = clRed;
   startPoint.x = 250;
   startPoint.y = 250;
   oldPoint.x = startPoint.x;
   oldPoint.y = startPoint.y;
   plotStartingPoint();
}

//---------------------------------- PLOT NEXT LEG WITHOUT CALLING A FUNCTION
void __fastcall TForm1::ButtonPlotNextLegWOFunctionClick(TObject *Sender)
{
   // grab the bearing from the edit box
   // we must convert text string to floating point
   bearing = StrToFloat(EditBearing->Text);
   // the angle increases counterclockwise; we want it increasing clockwise
   bearing = 360 - bearing;
   // the angle zero points down; we want it pointing up
   bearing = bearing + 180;
   // convert degrees to radians to satisfy trigonometric functions
   bearing = (bearing * M_PI) / 180;
   // grab the distance from the edit box
   distance = StrToFloat(EditDistance->Text);

   // calculate the newPoint position
   newPoint.x = oldPoint.x + distance * sin(bearing);
   newPoint.y = oldPoint.y + distance * cos(bearing);
   // render the new leg of the traverse
   Form1->Canvas->MoveTo(oldPoint.x, oldPoint.y);
   Form1->Canvas->LineTo(newPoint.x, newPoint.y);
   Form1->Canvas->Ellipse(newPoint.x-2, newPoint.y-2,
      newPoint.x+2, newPoint.y+2);   
   // the newPoint becomes the oldPoint
   oldPoint.x = newPoint.x;
   oldPoint.y = newPoint.y;
}

//========================================================= NEXT HUB FUNCTION
//  notice that it operates on the global variables oldPoint and newPoint
void nextHub (float bearing, float distance) {
   bearing = ((360 + 180 - bearing) * M_PI) / 180;
   newPoint.x = oldPoint.x + distance * sin(bearing);
   newPoint.y = oldPoint.y + distance * cos(bearing);
}

//----------------------------- PLOT NEXT LEG WHILE CALLING A FUNCTION BUTTON
void __fastcall TForm1::ButtonPlotNextLegWFunctionClick(TObject *Sender)
{
   // grab the bearing and distance from the edit boxes
   bearing = StrToFloat(EditBearing->Text);
   distance = StrToFloat(EditDistance->Text);
   // call the function with the oldPoint, bearing and distance
   // the function will update the global variables newPoint
   nextHub (bearing, distance);
   // render the line and new point
   Form1->Canvas->MoveTo(oldPoint.x, oldPoint.y);
   Form1->Canvas->LineTo(newPoint.x, newPoint.y);
   Form1->Canvas->Ellipse(newPoint.x-2, newPoint.y-2,
      newPoint.x+2, newPoint.y+2);
   // get ready for a new newPoint
   oldPoint.x = newPoint.x;
   oldPoint.y = newPoint.y;
}

//================================================== RECURSIVE LOOPS FUNCTION
void recursiveLoops (void) {
   bearing = StrToFloat(Form1->EditBearing->Text);
   distance = StrToFloat(Form1->EditDistance->Text);
   deltaBearing = StrToFloat(Form1->EditDeltaBearing->Text);
   deltaDistance = StrToFloat(Form1->EditDeltaDistance->Text);
   loops = StrToInt(Form1->EditLoops->Text);
   for (int i = 0; i <= loops; i++ ) {
      bearing = bearing + deltaBearing;
      distance = distance + deltaDistance;
      nextHub (bearing, distance);
      // render the line and new point
      Form1->Canvas->MoveTo(oldPoint.x, oldPoint.y);
      Form1->Canvas->LineTo(newPoint.x, newPoint.y);
      Form1->Canvas->Ellipse(newPoint.x-2, newPoint.y-2,
         newPoint.x+2, newPoint.y+2);
      // get ready for a new newPoint
      oldPoint.x = newPoint.x;
      oldPoint.y = newPoint.y;
   }
}

//------------------------------------------------------------ ON FORM CREATE
void __fastcall TForm1::FormCreate(TObject *Sender)
{
   initialize();
}

//---------------------------------------------- CENTER STARTING POINT BUTTON
void __fastcall TForm1::ButtonCenterClick(TObject *Sender)
{
   initialize();
}

//------------------------------------------------------------ REFRESH BUTTON
void __fastcall TForm1::ButtonRefreshClick(TObject *Sender)
{
   Refresh();
}

//---------------------------------------------------------- RUN LOOPS BUTTON
void __fastcall TForm1::ButtonRunLoopsClick(TObject *Sender)
{
   recursiveLoops();
}

//------------------------------------------------------------- ON FORM PAINT
void __fastcall TForm1::FormPaint(TObject *Sender)
{
   plotStartingPoint();
}

//--------------------------------------------------- SET NEW ORIGIN ON CLICK
void __fastcall TForm1::FormMouseDown(TObject *Sender, TMouseButton Button,
      TShiftState Shift, int X, int Y)
{
   oldPoint.x = X;
   oldPoint.y = Y;
   plotStartingPoint();
}

//========================================================== THAT'S ALL FOLKS