# Source code for arcade.utils

```import math
import random
from io import StringIO
from arcade.arcade_types import Point, Vector

[docs]def lerp(v1: float, v2: float, u: float) -> float:
"""linearly interpolate between two values"""
return v1 + ((v2 - v1) * u)

[docs]def lerp_vec(v1: Vector, v2: Vector, u: float) -> Vector:
return (
lerp(v1[0], v2[0], u),
lerp(v1[1], v2[1], u)
)

[docs]def rand_in_rect(bottom_left: Point, width: float, height: float) -> Point:
return (
random.uniform(bottom_left[0], bottom_left[0] + width),
random.uniform(bottom_left[1], bottom_left[1] + height)
)

[docs]def rand_in_circle(center: Point, radius: float):
"""
Generate a point in a circle, or can think of it as a vector pointing
a random direction with a random magnitude <= radius
Reference: https://stackoverflow.com/a/30564123
Note: This algorithm returns a higher concentration of points around the center of the circle
"""
# random angle
angle = 2 * math.pi * random.random()
# random radius
r = radius * random.random()
# calculating coordinates
return (
r * math.cos(angle) + center[0],
r * math.sin(angle) + center[1]
)

[docs]def rand_on_circle(center: Point, radius: float) -> Point:
"""Note: by passing a random value in for float, you can achieve what rand_in_circle() does"""
angle = 2 * math.pi * random.random()
return (
radius * math.cos(angle) + center[0],
radius * math.sin(angle) + center[1]
)

[docs]def rand_on_line(pos1: Point, pos2: Point) -> Point:
""" Given two points defining a line, return a random point on that line."""
u = random.uniform(0.0, 1.0)
return lerp_vec(pos1, pos2, u)

[docs]def rand_angle_360_deg():
""" Return a random angle in degrees. """
return random.uniform(0.0, 360.0)

[docs]def rand_angle_spread_deg(angle: float, half_angle_spread: float) -> float:
s = random.uniform(-half_angle_spread, half_angle_spread)
return angle + s

[docs]def rand_vec_spread_deg(angle: float, half_angle_spread: float, length: float) -> Vector:
a = rand_angle_spread_deg(angle, half_angle_spread)
vel = _Vec2.from_polar(a, length)
return vel.as_tuple()

[docs]def rand_vec_magnitude(angle: float, lo_magnitude: float, hi_magnitude: float) -> Vector:
mag = random.uniform(lo_magnitude, hi_magnitude)
vel = _Vec2.from_polar(angle, mag)
return vel.as_tuple()

class _Vec2:
"""
2D vector used to do operate points and vectors

Note: intended to be used for internal implementations only. Should not be part of public interfaces
(ex: function parameters or return values).
"""

__slots__ = ['x', 'y']

def __init__(self, x, y=None):
try:
# see if first argument is an iterable with two items
self.x = x[0]
self.y = x[1]
except TypeError:
self.x = x
self.y = y

@staticmethod
def from_polar(angle, radius):
rads = math.radians(angle)
return _Vec2(radius * math.cos(rads), radius * math.sin(rads))

def __add__(self, other):
return _Vec2(self.x + other.x, self.y + other.y)

def __sub__(self, other):
return _Vec2(self.x - other.x, self.y - other.y)

def __mul__(self, other):
return _Vec2(self.x * other.x, self.y * other.y)

def __truediv__(self, other):
return _Vec2(self.x / other.x, self.y / other.y)

def __iter__(self):
yield self.x
yield self.y

def length(self):
"""return the length (magnitude) of the vector"""
return math.sqrt(self.x**2 + self.y**2)

def dot(self, other):
return self.x * other.x + self.y * other.y

def __repr__(self):
return f"Vec2({self.x},{self.y})"

def rotated(self, angle):
"""Returns the new vector resulting when this vector is rotated by the given angle in degrees"""
rads = math.radians(angle)
cosine = math.cos(rads)
sine = math.sin(rads)
return _Vec2(
(self.x*cosine) - (self.y*sine),
(self.y*cosine) + (self.x*sine)
)

def as_tuple(self) -> Point:
return self.x, self.y

[docs]def generate_uuid_from_kwargs(**kwargs) -> str:
"""
Given key/pair combos, returns a string in uuid format.
Such as `text='hi', size=32` it will return "text-hi-size-32".
Called with no parameters, id does NOT return a random unique id.
"""
if len(kwargs) == 0:
raise Exception("generate_uuid_from_kwargs has to be used with kwargs, please check the doc.")

with StringIO() as guid:
for key, value in kwargs.items():
guid.write(str(key))
guid.write(str(value))
guid.write("-")
return guid.getvalue()
```