Mercurial > traipse_dev
view orpg/mapper/map_utils.py @ 32:c223c1051f4a traipse_dev
Update Manager moves into Beta 0.3 with a nice new look. The skeleton is
designed, not the functionality will be added.
author | sirebral |
---|---|
date | Sun, 02 Aug 2009 16:43:55 -0500 |
parents | 072ffc1d466f |
children | 449a8900f9ac |
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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