Mercurial > traipse_dev

annotate orpg/mapper/map_utils.py @ 71:449a8900f9ac ornery-dev

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Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
author sirebral
date Thu, 20 Aug 2009 03:00:39 -0500
parents 072ffc1d466f
children
rev   line source
71
449a8900f9ac Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
sirebral
parents: 20
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1 """
449a8900f9ac Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
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2 file: map_utils.py
449a8900f9ac Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
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3
449a8900f9ac Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
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4 This file contains generic utility functions
449a8900f9ac Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
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5 for use in the openrpg mapping system
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6 """
0
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7
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8 import math
71
449a8900f9ac Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
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9 """
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10 distance_between()
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11 Returns the distance between two points
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12 """
0
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13 def distance_between( x1, y1, x2, y2 ):
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14 "Returns the distance between two points"
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15 dx = x2 - x1
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16 dy = y2 - y1
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17 return math.sqrt( dx*dx + dy*dy )
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18
71
449a8900f9ac Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
sirebral
parents: 20
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19 """
449a8900f9ac Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
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20 proximity_test()
449a8900f9ac Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
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21 Tests if 'test_point' (T) is close (within 'threshold' units) to the
449a8900f9ac Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
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parents: 20
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22 line segment 'start_point' to 'end_point' (PQ).
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23
449a8900f9ac Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
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24 The closest point (R) to T on the line PQ is given by:
449a8900f9ac Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
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25 R = P + u (Q - P)
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26 TR is perpendicular to PQ so:
449a8900f9ac Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
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27 (T - R) dot (Q - P) = 0
449a8900f9ac Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
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28 Solving these two equations gives the equation for u (see below).
449a8900f9ac Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
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29
449a8900f9ac Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
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30 If u < 0 or u > 1 then R is not within the line segment and we simply
449a8900f9ac Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
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parents: 20
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31 test against point P or Q.
449a8900f9ac Code refining almost completed, for this round. Some included files are still in need of some clean up, but this is test worthy.
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parents: 20
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32 """
0
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33 def proximity_test( start_point, end_point, test_point, threshold ):
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34 "Test if a point is close to a line segment"
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35 x1,y1 = start_point
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36 x2,y2 = end_point
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37 xt,yt = test_point
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38 x1 = float(x1)
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39 x2 = float(x2)
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40 y1 = float(y1)
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41 y2 = float(y2)
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42 xt = float(xt)
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43 yt = float(yt)
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44
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45 # Coincident points?
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46 if x1 == x2 and y1 == y2: d = distance_between(xt, yt, x1, y1)
0
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47 else:
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48 dx = x2 - x1
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49 dy = y2 - y1
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50 u = ((xt - x1) * dx + (yt - y1) * dy) / (dx*dx + dy*dy)
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51 if u < 0: d = distance_between(xt, yt, x1, y1)
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52 elif u > 1: d = distance_between(xt, yt, x2, y2)
0
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53 else:
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54 xr = x1 + u * dx
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55 yr = y1 + u * dy
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56 d = distance_between(xt, yt, xr, yr)
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57 return d <= threshold