#include "svt.h"
    #include "draw.h"
    //Vector graphics drawing demo

    #define ARROWSTEPS 30
    #define SWEEPSTEPS 20

    int arrowStepCount;
    int sweepStepCount;

    iPoint arrow[4];   //Polygon of an arrowhead pointer

    float arrowAngle;   //Direction to rotate arrow
    float sweepAngle;   //Direction of radar sweep arm
    iPoint sweepArm;   //Point at tip of radar sweep arm
    int arrowX, arrowY;   //Centre of arrow
    int radarX, radarY;   //Centre of radar sweep arm

    //Resets polygon for arrow to avoid cumulative rounding errors
    void ResetArrow() {
       //define a triangle polygon
       arrow[0].x=80;
       arrow[0].y=20;
       arrow[1].x=50;
       arrow[1].y=90;
       arrow[2].x=80;
       arrow[2].y=70;
       arrow[3].x=110;
       arrow[3].y=90;
       //obviously I could define it small but I
       //wanted to test these routines!
       ScalePoly(4, arrow, 80, 60, 0.3);
       MovePoly(4, arrow, -60, -40);
    }

    //Draws arrow at new angle
    void DrawArrow(float radAngle) {
       //Erase old copy
       DrawPoly(4, arrow, BLACK);
       //Recalculate new rotated angle
       ResetArrow();
       RotatePoly(4, arrow, arrowX, arrowY, radAngle);
       //Draw new arrow
       DrawPoly(4, arrow, YELLOW);
    }

    //Draws radar arm at new angle
    void DrawRadarArm(float radAngle) {
       //Erase old line
       DrawLine(radarX, radarY, sweepArm.x, sweepArm.y, BLACK);
       //define 'north' tip position of sweep arm
       sweepArm.x=radarX;
       sweepArm.y=radarY-16;
       //Rotate point about centre
       RotatePoint(&sweepArm, radarX, radarY, radAngle);
       //Draw new arm
       DrawLine(radarX,radarY, sweepArm.x, sweepArm.y, GREEN);
    }

    //Backdrop headup display graphics - instrument panels & crosshairs
    void DrawBackdrop() {
       //Seems a bit brutal to have to close graphics but it's
       //the only way to clear the screen that'll let us draw
       //on it properly again - ClearScreen or ClearRectangle screw up
       CloseGraphics();
       OpenGraphics();

       //Side panel
       SetLineWidth(5);
       int i, j;
       for (i=0; i<8; i++)
          for (j=0; j<8; j++) {
             Plot(i*5,j*5,BLACK);
             Plot(120+i*5,j*5,BLACK);
          }
       SetLineWidth(1);

       //Some concentric circles
       DrawCircle(arrowX, arrowY, 19, RED);
       DrawCircle(radarX, radarY, 19, GREEN);

       //Crosshairs
       DrawLine(80, 40, 80, 80, WHITE);
       DrawLine(60, 60, 100, 60, WHITE);
       DrawCircle(80, 60, 10, WHITE);
    }

    //Setup
    void Start() {
       OpenGraphics();
       SetLineWidth(1); //needed otherwise we draw huge  thick points!

       arrowStepCount=0;
       sweepStepCount=0;
       arrowAngle = 2 * PI / ARROWSTEPS;
       sweepAngle = 2 * PI / SWEEPSTEPS;

       arrowX=20;
       arrowY=20;
       radarX=140;
       radarY=20;

       sweepArm.x=140;
       sweepArm.y=20;

       ResetArrow();
       DrawBackdrop();
    }

    //Main program loop - Run gets called until it returns false
    bool Run() {
       //Just wait around for the home key to be pressed
       if (GetRemoteKeyStatus(KEY_HOME))
          return false;
       else {
          //reset angle counts
          if (arrowStepCount == ARROWSTEPS)
             arrowStepCount=0;
          if (sweepStepCount == SWEEPSTEPS)
             sweepStepCount=0;

          DrawArrow(arrowAngle * arrowStepCount++);
          DrawRadarArm(sweepAngle * sweepStepCount++);

          Show();

          Sleep(250);
          return true;
       }
    }

    //Cleanup
    void End() {
       CloseGraphics();
    }