Work on Issue pythonarcade#89 and Issue pythonarcade#110. Improve col…

…lision detection. Improve the speed, and remove issues around floating point errors.

arcade/geometry.py

@@ -7,6 +7,8 @@
 from typing import List
 from arcade.arcade_types import PointList
 
+import math
+
 PRECISION = 2
 
 def are_polygons_intersecting(poly_a: PointList,
@@ -35,6 +37,7 @@ def are_polygons_intersecting(poly_a: PointList,
     True False False
 
     """
+
     for polygon in (poly_a, poly_b):
 
         for i1 in range(len(polygon)):
@@ -48,22 +51,22 @@ def are_polygons_intersecting(poly_a: PointList,
             min_a, max_a, min_b, max_b = (None,) * 4
 
             for poly in poly_a:
-                projected = normal[0] * poly[0] + normal[1] * poly[1]
+                projected = round(normal[0] * poly[0] + normal[1] * poly[1], 2)
 
-                if not min_a or round(projected, PRECISION) < round(min_a, PRECISION):
+                if not min_a or projected < min_a:
                     min_a = projected
-                if not max_a or round(projected, PRECISION) > round(max_a, PRECISION):
+                if not max_a or projected > max_a:
                     max_a = projected
 
             for poly in poly_b:
-                projected = normal[0] * poly[0] + normal[1] * poly[1]
+                projected = round(normal[0] * poly[0] + normal[1] * poly[1], 2)
 
-                if not min_b or round(projected, PRECISION) < round(min_b, PRECISION):
+                if not min_b or projected < min_b:
                     min_b = projected
-                if not max_b or round(projected, PRECISION) > round(max_b, PRECISION):
+                if not max_b or projected > max_b:
                     max_b = projected
 
-            if round(max_a, PRECISION) <= round(min_b, PRECISION) or round(max_b, PRECISION) <= round(min_a, PRECISION):
+            if max_a <= min_b or max_b <= min_a:
                 return False
 
     return True
@@ -96,6 +99,21 @@ def check_for_collision(sprite1: Sprite, sprite2: Sprite) -> bool:
         raise TypeError("Parameter 1 is not an instance of the Sprite class.")
     if not isinstance(sprite2, Sprite):
         raise TypeError("Parameter 2 is not an instance of the Sprite class.")
+
+    collision_radius_sum = sprite1.collision_radius + sprite2.collision_radius
+
+    diff_x = abs(sprite1.center_x - sprite2.center_x)
+
+    if diff_x > collision_radius_sum:
+        return False
+    diff_y = abs(sprite2.center_y - sprite2.center_y)
+    if diff_y > collision_radius_sum:
+        return False
+
+    distance = math.sqrt(diff_x * diff_x + diff_y + diff_y)
+    if distance > collision_radius_sum:
+        return False
+
     return are_polygons_intersecting(sprite1.points, sprite2.points)
 
 

arcade/sprite.py

@@ -131,6 +131,7 @@ def __init__(self,
         self.alpha = 1.0
         self.sprite_lists = []
         self.transparent = True
+        self._collision_radius = None
 
         self.can_cache = True
         self._points = None
@@ -215,6 +216,16 @@ def get_points(self) -> List[List[float]]:
 
     points = property(get_points, set_points)
 
+    def _set_collision_radius(self, collision_radius):
+        self._collision_radius = collision_radius
+
+    def _get_collision_radius(self):
+        if not self._collision_radius:
+            self._collision_radius = max(self.width, self.height)
+        return self._collision_radius
+
+    collision_radius = property(_get_collision_radius, _set_collision_radius)
+
     def _get_bottom(self) -> float:
         """
         Return the y coordinate of the bottom of the sprite.
@@ -303,7 +314,6 @@ def _set_center_y(self, new_value: float):
 
     center_y = property(_get_center_y, _set_center_y)
 
-
     def _get_change_x(self) -> float:
         """ Get the velocity in the x plane of the sprite. """
         return self.velocity[0]
@@ -324,8 +334,6 @@ def _set_change_y(self, new_value: float):
 
     change_y = property(_get_change_y, _set_change_y)
 
-
-
     def _get_angle(self) -> float:
         """ Get the angle of the sprite's rotation. """
         return self._angle