Line and fillPolygon
Author
Zhou Renjian
Create@
2005-04-05 17:59
function Line(x1,y1,x2,y2) {
if (x1 > x2)
{
var _x2 = x2;
var _y2 = y2;
x2 = x1;
y2 = y1;
x1 = _x2;
y1 = _y2;
}
var dx = x2-x1, dy = Math.abs(y2-y1),
x = x1, y = y1,
yIncr = (y1 > y2)? -1 : 1;
if (dx >= dy)
{
var pr = dy<<1,
pru = pr - (dx<<1),
p = pr-dx,
ox = x;
while ((dx--) > 0)
{
++x;
if (p > 0)
{
this.mkDiv(ox, y, x-ox, 1);
y += yIncr;
p += pru;
ox = x;
}
else p += pr;
}
this.mkDiv(ox, y, x2-ox+1, 1);
}
else
{
var pr = dx<<1,
pru = pr - (dy<<1),
p = pr-dy,
oy = y;
if (y2 <= y1)
{
while ((dy--) > 0)
{
if (p > 0)
{
this.mkDiv(x++, y, 1, oy-y+1);
y += yIncr;
p += pru;
oy = y;
}
else
{
y += yIncr;
p += pr;
}
}
this.mkDiv(x2, y2, 1, oy-y2+1);
}
else
{
while ((dy--) > 0)
{
y += yIncr;
if (p > 0)
{
this.mkDiv(x++, oy, 1, y-oy);
p += pru;
oy = y;
}
else p += pr;
}
this.mkDiv(x2, oy, 1, y2-oy+1);
}
}
}
function fillPolygon(array_x, array_y)
{
var i;
var y;
var miny, maxy;
var x1, y1;
var x2, y2;
var ind1, ind2;
var ints;
var n = array_x.length;
if (!n) return;
miny = array_y[0];
maxy = array_y[0];
for (i = 1; i < n; i++)
{
if (array_y[i] < miny)
miny = array_y[i];
if (array_y[i] > maxy)
maxy = array_y[i];
}
for (y = miny; y <= maxy; y++)
{
var polyInts = new Array();
ints = 0;
for (i = 0; i < n; i++)
{
if (!i)
{
ind1 = n-1;
ind2 = 0;
}
else
{
ind1 = i-1;
ind2 = i;
}
y1 = array_y[ind1];
y2 = array_y[ind2];
if (y1 < y2)
{
x1 = array_x[ind1];
x2 = array_x[ind2];
}
else if (y1 > y2)
{
y2 = array_y[ind1];
y1 = array_y[ind2];
x2 = array_x[ind1];
x1 = array_x[ind2];
}
else continue;
if ((y >= y1) && (y < y2))
polyInts[ints++] = Math.round((y-y1) * (x2-x1) / (y2-y1) + x1);
else if ((y == maxy) && (y > y1) && (y <= y2))
polyInts[ints++] = Math.round((y-y1) * (x2-x1) / (y2-y1) + x1);
}
polyInts.sort(integer_compare);
for (i = 0; i < ints; i+=2)
{
w = polyInts[i+1]-polyInts[i]
this.mkDiv(polyInts[i], y, polyInts[i+1]-polyInts[i]+1, 1);
}
}
}