/* General line-drawing routine which takes line styles into account */

#include "plplot.h"
#include "declare.h"
#include <math.h>

static PLINT lastx=-100000, lasty=-100000;

void genlin(x1,y1,x2,y2)
PLINT x1,y1,x2,y2;
{
   PLINT nx,ny;
   PLINT modulo, incr, dx, dy, diax, diay, i, temp, x, y;
   PLINT px, py, tstep;

/* Check for solid line */

   if (nms == 0) {
      grline(x1,y1,x2,y2);
      return;
   }

/* Check if pattern needs to be restarted */

   if (x1 != lastx || y1 != lasty) {
        curel = 0;
        pendn = 1;
        timecnt = 0;
        alarm = mark[curel];
        if (x1 == x2 && y1 == y2) grline(x1,y1,x2,y2);
   }

   lastx = x1;
   lasty = y1;

   if (x1 == x2 && y1 == y2) return;

   nx = x2 - x1;
   ny = y2 - y1;

   if (abs(ny) > abs(nx)) {
        modulo = abs(ny);
        incr   = abs(nx);
        dx     = 0;
        dy     = -1;
        if (ny > 0) dy = 1;
   }
   else {
        modulo = abs(nx);
        incr   = abs(ny);
        dx     = -1;
        if (nx > 0) dx = 1;
        dy     = 0;
   }

   diax = -1;
   if (nx > 0) diax = 1;
   diay = -1;
   if (ny > 0) diay = 1;

   temp = modulo/2;
   x = x1;
   y = y1;
   i = 1;

/* Compute the timer step */

   tstep = sqrt(pow((double)(abs(nx)*umx),2.)+
                   pow((double)(abs(ny)*umy),2.))/modulo;

loop:
   if (i > modulo) goto exit;
   i = i+1;
   temp = temp+incr;
   px = x;
   py = y;
   if (temp > modulo) {
          temp = temp-modulo;
          x = x + diax;
          y = y + diay;
   }
   else {
          x = x + dx;
          y = y + dy;
   }
   timecnt += tstep;
   if (timecnt >= alarm) {
          plupd();
          if (pendn == 0) grline(lastx,lasty,px,py);
          lastx = x;
          lasty = y;
   }
   goto loop;

exit:
   if (pendn != 0) grline(lastx,lasty,x,y);
   lastx = x2;
   lasty = y2;
}