+""" Light ray manipulation. Pew. Pew. Pew. Wommmm. """
+
+import pymunk
+import pymunk.pygame_util
+
+from .constants import SCREEN_SIZE
+from .utils import debug_timer
+
+
+def screen_rays(pos):
+ """ An iterable that returns ordered rays from pos to the edge of the
+ screen, starting with the edge point (0, 0) and continuing clockwise
+ in pymunk coordinates.
+ """
+ w, h = SCREEN_SIZE
+ left, right, bottom, top = 0, w, 0, h
+ step = 1
+ for y in range(0, h, step):
+ yield pymunk.Vec2d(left, y)
+ for x in range(0, w, step):
+ yield pymunk.Vec2d(x, top)
+ for y in range(top, -1, -step):
+ yield pymunk.Vec2d(right, y)
+ for x in range(right, -1, -step):
+ yield pymunk.Vec2d(x, bottom)
+
+
+@debug_timer("rays.calculate_ray_polys")
+def calculate_ray_polys(space, body, position, light_filter):
+ position = pymunk.Vec2d(position)
+ vertices = [position]
+ ray_polys = []
+ for ray in screen_rays(position):
+ info = space.segment_query_first(position, ray, 1, light_filter)
+ point = ray if info is None else info.point
+ vertices.append(point)
+ if len(vertices) > 3:
+ trial_poly = pymunk.Poly(None, vertices)
+ trial_poly.update(pymunk.Transform.identity())
+ query_prev = trial_poly.point_query(vertices[-2])
+ query_pos = trial_poly.point_query(position)
+ if query_prev.distance < -0.01 or query_pos.distance < -0.01:
+ new_poly = pymunk.Poly(body, vertices[:-1])
+ vertices = [position, vertices[-1]]
+ ray_polys.append(new_poly)
+ else:
+ vertices = trial_poly.get_vertices() + [point]
+ if len(vertices) > 2:
+ ray_polys.append(pymunk.Poly(body, vertices))
+ return ray_polys