view orpg/mapper/map_utils.py @ 105:2f2bebe9c77f alpha

Traipse Alpha 'OpenRPG' {091006-03} Traipse is a distribution of OpenRPG that is designed to be easy to setup and go. Traipse also makes it easy for developers to work on code without fear of sacrifice. 'Ornery-Orc' continues the trend of 'Grumpy' and adds fixes to the code. 'Ornery-Orc's main goal is to offer more advanced features and enhance the productivity of the user. Update Summary: 00: Adds Bookmarks (Alpha) with cool Smiley Star and Plus Symbol images! 01: Forgot the default_server_bookmarks.xml; added. 02: Bookmarks working with no errors now! Sweet! 03: Changes made to the map for increased portability. SnowDog has changes planned in Core, though. Added an initial push to the BCG. Not much to see, just shows off how it is re-writing Main code.
author sirebral
date Tue, 06 Oct 2009 22:16:34 -0500
parents 449a8900f9ac
children
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"""
 file: map_utils.py

 This file contains generic utility functions
 for use in the openrpg mapping system
"""

import math
"""
 distance_between()
 Returns the distance between two points
"""
def distance_between( x1, y1, x2, y2 ):
   "Returns the distance between two points"
   dx = x2 - x1
   dy = y2 - y1
   return math.sqrt( dx*dx + dy*dy )

"""
 proximity_test()
 Tests if 'test_point' (T) is close (within 'threshold' units) to the
 line segment 'start_point' to 'end_point' (PQ).

 The closest point (R) to T on the line PQ is given by:
    R = P + u (Q - P)
 TR is perpendicular to PQ so:
    (T - R) dot (Q - P) = 0
 Solving these two equations gives the equation for u (see below).

 If u < 0 or u > 1 then R is not within the line segment and we simply
 test against point P or Q.
"""
def proximity_test( start_point, end_point, test_point, threshold ):
   "Test if a point is close to a line segment"
   x1,y1 = start_point
   x2,y2 = end_point
   xt,yt = test_point
   x1 = float(x1)
   x2 = float(x2)
   y1 = float(y1)
   y2 = float(y2)
   xt = float(xt)
   yt = float(yt)

   # Coincident points?
   if x1 == x2 and y1 == y2: d = distance_between(xt, yt, x1, y1)
   else:
       dx = x2 - x1
       dy = y2 - y1
       u = ((xt - x1) * dx + (yt - y1) * dy) / (dx*dx + dy*dy)
       if u < 0: d = distance_between(xt, yt, x1, y1)
       elif u > 1: d = distance_between(xt, yt, x2, y2)
       else:
           xr = x1 + u * dx
           yr = y1 + u * dy
           d = distance_between(xt, yt, xr, yr)
   return d <= threshold