X-Git-Url: https://git.yukkurigames.com/?p=python-bulletml.git;a=blobdiff_plain;f=bulletml%2Fcollision.py;h=2e88b3c0a492008a8c62cb0a23c0c92fbd9f3f4f;hp=1683e58f6ca70fa583e65e9e967835d2c6831472;hb=HEAD;hpb=ee9429c2c319d5d794e49da7b0fe13fca9945194

diff --git a/bulletml/collision.py b/bulletml/collision.py
index 1683e58..2e88b3c 100644
--- a/bulletml/collision.py
+++ b/bulletml/collision.py
@@ -1,7 +1,7 @@
 """Simple collision check.
 
 This module provides simple collision checking appropriate for
-shmups. It provides a routine to check whether two moving circles
+shmups. It provides routines to check whether two moving circles
 collided during the past frame.
 
 An equivalent C-based version will be used automatically if it was
@@ -30,7 +30,10 @@ def overlaps(a, b):
 
     dx = a.x - b.x
     dy = a.y - b.y
-    radius = getattr(a, 'radius', 0.5) + getattr(b, 'radius', 0.5)
+    try:
+        radius = a.radius + b.radius
+    except AttributeError:
+        radius = getattr(a, 'radius', 0.5) + getattr(b, 'radius', 0.5)
 
     return dx * dx + dy * dy <= radius * radius
 
@@ -53,27 +56,32 @@ def collides(a, b):
     yb = b.y
 
     # Treat b as a point, we only need one radius.
-    radius = getattr(a, 'radius', 0.5) + getattr(b, 'radius', 0.5)
+    try:
+        radius = a.radius + b.radius
+    except AttributeError:
+        radius = getattr(a, 'radius', 0.5) + getattr(b, 'radius', 0.5)
 
     # Previous frame locations.
-    pxa = getattr(a, 'px', xa)
-    pya = getattr(a, 'py', ya)
-    pxb = getattr(b, 'px', xb)
-    pyb = getattr(b, 'py', yb)
+    try: pxa = a.px
+    except KeyError: pxa = xa
+    try: pya = a.py
+    except KeyError: pya = ya
+    try: pxb = b.px
+    except KeyError: pxb = xb
+    try: pyb = b.py
+    except KeyError: pyb = yb
 
     # Translate b's final position to be relative to a's start.
     # And now, circle/line collision.
     dir_x = pxa + (xb - xa) - pxb
     dir_y = pya + (yb - ya) - pyb
 
-    if abs(dir_x) < 0.0001 and abs(dir_y) < 0.0001:
-        # b did not move relative to a, so do point/circle.
-        dx = pxb - pxa
-        dy = pyb - pya
-        return dx * dx + dy * dy < radius * radius
-
     diff_x = pxa - pxb
     diff_y = pya - pyb
+    if (dir_x < 0.0001 and dir_x > -0.0001
+        and dir_y < 0.0001 and dir_y > -0.0001):
+        # b did not move relative to a, so do point/circle.
+        return diff_x * diff_x + diff_y * diff_y < radius * radius
 
     # dot(diff, dir) / dot(dir, dir)
     t = (diff_x * dir_x + diff_y * dir_y) / (dir_x * dir_x + dir_y * dir_y)