SZanlongo

3/16/2016 - 7:59 PM

Algorithm for drawing a 4-connected line

From https://stackoverflow.com/questions/5186939/algorithm-for-drawing-a-4-connected-line

```
def line(x0, y0, x1, y1, color):
dx = abs(x1 - x0) # distance to travel in X
dy = abs(y1 - y0) # distance to travel in Y
if x0 < x1:
ix = 1 # x will increase at each step
else:
ix = -1 # x will decrease at each step
if y0 < y1:
iy = 1 # y will increase at each step
else:
iy = -1 # y will decrease at each step
e = 0 # Current error
for i in range(dx + dy):
draw_pixel(x0, y0, color)
e1 = e + dy
e2 = e - dx
if abs(e1) < abs(e2):
# Error will be smaller moving on X
x0 += ix
e = e1
else:
# Error will be smaller moving on Y
y0 += iy
e = e2
```