# simu - Robot simulation. {{{ # # Copyright (C) 2009 Nicolas Schodet # # APBTeam: # Web: http://apbteam.org/ # Email: team AT apbteam DOT org # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program; if not, write to the Free Software # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. # # }}} """Obstacle with a round shape.""" from math import pi, cos, sin, sqrt from utils.observable import Observable from simu.utils.vector import vector class RoundObstacle (Observable): def __init__ (self, radius, level = 0): Observable.__init__ (self) self.pos = None self.radius = radius self.level = level def intersect (self, a, b): """If the segment [AB] intersects the obstacle, return distance from a to intersection point, else, return None.""" if self.pos is None: return None a, b = vector (a), vector (b) vab = b - a ab = abs (vab) # distance AB. n = vab.unit () # vector of length 1. o = vector (self.pos) # obstacle center. # To check if the line (AB) intersects the circle, compute distance # from circle center to line using a dot product. vao = o - a # vector AO. # abs of dot product. doc = abs (vao * n.normal ()) if doc < self.radius: # Line intersects, check if segment intersects. m = vao * n f = sqrt (self.radius ** 2 - doc ** 2) if m - f > 0 and m - f < ab: return m - f elif m + f > 0 and m + f < ab: return m + f return None