X-Git-Url: https://git.yukkurigames.com/?p=python-bulletml.git;a=blobdiff_plain;f=bulletml%2Fcollision.py;h=2e88b3c0a492008a8c62cb0a23c0c92fbd9f3f4f;hp=f185745ab77f410bcd541846a2b00d28badfd663;hb=HEAD;hpb=0f067785de711c772c2c44c7f1e1cf8b44b2704f

diff --git a/bulletml/collision.py b/bulletml/collision.py
index f185745..2e88b3c 100644
--- a/bulletml/collision.py
+++ b/bulletml/collision.py
@@ -1,9 +1,13 @@
 """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
+compiled and installed with the module. If available, it will be noted
+in the docstrings for the functions.
+
 Basic Usage:
 
     from bulletml.collision import collides
@@ -20,11 +24,16 @@ def overlaps(a, b):
     Usually, you'll want to use the 'collides' method instead, but
     this one can be useful for just checking to see if the player has
     entered an area or hit a stationary oject.
+
+    (This function is unoptimized.)
     """
 
     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
 
@@ -37,6 +46,8 @@ def collides(a, b):
     px, py - not required, defaults to x, y, previous frame position
     radius - not required, defaults to 0.5
 
+    (This function is unoptimized.)
+
     """
     # Current locations.
     xa = a.x
@@ -45,27 +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)
@@ -79,3 +95,18 @@ def collides(a, b):
 
     # dist_sq < radius_sq
     return dist_x * dist_x + dist_y * dist_y <= radius * radius
+
+def collides_all(a, others):
+    """Filter the second argument to those that collide with the first.
+
+    This is equivalent to filter(lambda o: collides(a, o), others),
+    but is much faster when the compiled extension is available (which
+    it is not currently).
+
+    """
+    return filter(lambda o: collides(a, o), others)
+
+try:
+    from bulletml._collision import collides, overlaps, collides_all
+except ImportError:
+    pass