Sierpinski arrowhead curve: Difference between revisions
→{{header|Processing Python mode}}
m (→{{header|Phix}}: added syntax colouring, link to run online) |
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'''The sketch can be run online''' :<BR> [https://Trinket.io/processing/de6eddb155 here.]
==={{header|Python}}===
<lang python>
import matplotlib.pyplot as plt
import math
def nextPoint(x, y, angle):
a = math.pi * angle / 180
x2 = (int)(round(x + (1 * math.cos(a))))
y2 = (int)(round(y + (1 * math.sin(a))))
return x2, y2
def expand(axiom, rules, level):
for l in range(0, level):
a2 = ""
for c in axiom:
if c in rules:
a2 += rules[c]
else:
a2 += c
axiom = a2
return axiom
def draw_lsystem(axiom, rules, angle, iterations):
xp = [1]
yp = [1]
direction = 0
for c in expand(axiom, rules, iterations):
if c == "F":
xn, yn = nextPoint(xp[-1], yp[-1], direction)
xp.append(xn)
yp.append(yn)
elif c == "-":
direction = direction - angle
if direction < 0:
direction = 360 + direction
elif c == "+":
direction = (direction + angle) % 360
plt.plot(xp, yp)
plt.show()
if __name__ == '__main__':
# Sierpinski Arrowhead Curve L-System Definition
s_axiom = "XF"
s_rules = {"X": "YF+XF+Y",
"Y": "XF-YF-X"}
s_angle = 60
draw_lsystem(s_axiom, s_rules, s_angle, 7)
</lang>
=={{header|Prolog}}==
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