def check_ray_circle_intersection(p1: Coordinates, p2: Coordinates,
c_mid: Coordinates, c_radius: float):
"""
Check whether a ray intersects a circle.
:param p1: starting point of ray
:param p2: end point of ray
:param c_mid: coordinates for the center of the circle
:param c_radius: radius of the circle
:return: True if intersection; False otherwise
"""
# Source: https://stackoverflow.com/a/1084899
# d is direction vector of ray, from start to end
# f is direction Vector from center sphere to ray start
d = Vector(p2.y - p1.y, p2.x - p1.x)
f = Vector(p1.y - c_mid.y, p1.x - c_mid.x)
a = d.dot_product(d)
b = 2 * f.dot_product(d)
c = f.dot_product(f) - c_radius**2
discriminant = b * b - 4 * a * c
if discriminant < 0:
return False
else:
discriminant = np.sqrt(discriminant)
t1 = (-b - discriminant) / (2 * a)
t2 = (-b + discriminant) / (2 * a)
return (0 <= t1 <= 1) or (0 <= t2 <= 1)
def get_point_on_line_distance_from_point(line_start, line_end, point,
distance) -> Coordinates:
a_side = distance
c_side = get_distance(line_start, point)
v_point = Vector(point.x - line_start.x, point.y - line_start.y)
v_line = Vector(line_end.x - line_start.x, line_end.y - line_start.y)
dot = v_point.dot_product(v_line)
a_angle = np.arccos(dot / v_point.get_magnitude() / v_line.get_magnitude())
from physics.trianglesolver import solve
(a_side, b_side, c_side, a_angle, b_angle,
c_angle) = solve(a=a_side, c=c_side, A=a_angle, ssa_flag='obtuse')
assert a_angle + b_angle + c_angle == np.radians(
180), 'a_angle: {} \nb_angle: {}\nc_angle: {}\n'.format(
a_angle, b_angle, c_angle)
# Compute exact point
angle = np.radians(get_angle(line_end, line_start))
x = line_start.x + b_side * np.cos(angle)
y = line_start.y + b_side * np.sin(angle)
return Coordinates(x, y)
