def apply_friction(body,
gravity,
damping,
dt,
friction,
rotFriction,
spin=0.0):
# Update velocity
Body.update_velocity(body, gravity, damping, dt)
# Get friction coefficients for velocity and angular velocity
m = body.mass
factor = friction * m
rotFactor = rotFriction * m
# Get velocity params
x = body.velocity.x
y = body.velocity.y
length = 1.0 / (abs(x) + abs(y) + 1e-5)
theta = body.angular_velocity
# Spinning objects turn sideways
a = [x * factor * length, y * factor * length]
a[0] += a[1] * spin * theta
a[1] -= a[0] * spin * theta
# If too slow, simply stop
if abs(x) < factor:
x = 0
else:
x -= a[0]
if abs(y) < factor:
y = 0
else:
y -= a[1]
# Ditto
if abs(theta) < rotFactor:
theta = 0
else:
theta -= rotFactor if theta > 0 else -rotFactor
# Set velocity
body.velocity = Vec2d(x, y)
body.angular_velocity = theta
def zero_gravity(body, gravity, damping, dt):
Body.update_velocity(body, (0, 0), damping, dt)