line1.c

#include <stdlib.h>
#include "vga256.h"

static const int LineStyle[4] =
{
  0xFFFF,                /* Solid Line Style              */
  0xCCCC,                /* Dotted Line                   */
  0xFC78,                /* Center Line                   */
  0xF8F8                 /* Dashed Line                   */
};

static int CurLineStyle;
static int CurLineWidth;

void SetLineStyle(unsigned char Pat, int UserPat, int LineWidth)
{
  CurLineStyle = Pat == 4 ? UserPat : LineStyle[Pat];
  CurLineWidth = LineWidth;
}

void Vect(int x1, int y1, int x2, int y2)
{
  int deltaX = abs(x2 - x1),
      deltaY = abs(y2 - y1),
      stepX = (x1 > x2) ? -1 : 1,
      stepY = (y1 > y2) ? -1 : 1,
      i = CurLineStyle,
      c;
  c = deltaX ? 0 : -1;
  while(1)
  {
    i = _rotl(i, 1);
    PutPixelFunc(x1, y1, i & 1 ? DrawColor : BkgrColor);
    if(x1 == x2 && y1 == y2)
      break;
    if(c < 0)
    {
      y1 += stepY;
      c += deltaX;
    }
    else
    {
      x1 += stepX;
      c -= deltaY;
    }
  }
}