def on_update(dt):
# going to store the old position, for collision purposes
old_pos = vec2d(cell.x, cell.y)
# move the cell towards it's velocity
cell.x += cell.velocity[0] * dt
cell.y += cell.velocity[1] * dt
# check for collisions against wall
# if one is found, get new position, to allow "sliding"
# against them
radius = cell_image.width / 2 * 0.8
i = 0
if cell.velocity != (0, 0):
while i < len(lines):
p1 = vec2d(lines[i], lines[i + 1])
p2 = vec2d(lines[i + 2], lines[i + 3])
line = p2 - p1
normal = line.perpendicular_normal()
vec = (cell.x, cell.y) + radius * normal
intersects = line_intersect(old_pos, vec, p1, p2)
if not intersects is None:
new_pos = calc_new_pos(old_pos, vec, p1, p2)
new_pos -= radius * normal
cell.x = new_pos.x
cell.y = new_pos.y
elif circle_point_intersect(cell.position, radius, p1):
direction = cell.position - p1
length = direction.length
move_by_distance = radius - length
new_pos = cell.position + direction.normalized() * move_by_distance
cell.x = new_pos.x
cell.y = new_pos.y
i += 4