Optional Pyrex extension for the collision module. More than doubles its speed.

[python-bulletml.git] / bulletml / collision.py

diff --git a/bulletml/collision.py b/bulletml/collision.py
index f185745..0394ed3 100644 (file)
--- a/bulletml/collision.py
+++ b/bulletml/collision.py
@@ -4,6 +4,9 @@ This module provides simple collision checking appropriate for
 shmups. It provides a routine to check whether two moving circles
 collided during the past frame.
 
+If Pyrex was available when installing, this will used optimized
+versions of the functions.
+
 Basic Usage:
 
     from bulletml.collision import collides
@@ -20,6 +23,8 @@ 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
@@ -37,6 +42,8 @@ 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
@@ -79,3 +86,18 @@ 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