from cs1graphics import *

w = 400
gap = 5

paper = Canvas(w,w)

# draw first half of black
for k in range(0,w,gap):
    partial = 1.0 * (w-k)/w
    line = Path(Point(partial*k, k + partial*(w-k)), Point(k,w))
    line.setBorderColor('black')
    paper.add(line)

# draw red in bottom-right quadrant
for k in range(0,w,gap):
    line = Path(Point(k,w), Point(w,w-k))
    line.setBorderColor('red')
    paper.add(line)

# draw blue in top-right quadrant
for k in range(0,w,gap):
    line = Path(Point(k,0), Point(w,k))
    line.setBorderColor('blue')
    paper.add(line)

# draw green in top-left quadrant
for k in range(0,w,gap):
    line = Path(Point(w-k,0), Point(0,k))
    line.setBorderColor('green')
    paper.add(line)

# draw second half of black
for k in range(0,w,gap):
    partial = 1.0 * (w-k)/w
    line = Path(Point(0,k), Point(partial*k, k + partial*(w-k)))
    line.setBorderColor('black')
    paper.add(line)