def update(self):
# The performance trick is that we don't keep a history,
# e.g. no list with all the previous segments in the growing root.
# We simply keep the position and heading of the last segment.
# The previous segments have been rendered in a texture, i.e. they are "frozen".
self.x, self.y = coordinates(self.x, self.y, self.radius, self.angle)
self.angle += random(-self.step, self.step)
self.time *= 0.8 + random(0.2)
def update(self):
# Calculate new position from the current heading and segment size.
# The coordinates() function takes a point, a distance and an angle,
# and returns the point at the given angle and distance from the given point.
x, y = coordinates(self.x, self.y, self.radius*3, self.angle)
self.angle += choice((-self.step, self.step))
# Confine the snake to the visible area.
self.x = max(0, min(x, 500))
self.y = max(0, min(y, 500))
# Add the new segment.
# Snake can have 200 segments maximum.
self.trail.insert(0, (x, y, self.radius))
self.trail = self.trail[:200]
