## matplotlib-checkins

 SF.net SVN: matplotlib:[8720] branches/v1_0_maint/lib/matplotlib/bezier.py From: - 2010-09-27 01:30:25 ```Revision: 8720 http://matplotlib.svn.sourceforge.net/matplotlib/?rev=8720&view=rev Author: leejjoon Date: 2010-09-27 01:30:19 +0000 (Mon, 27 Sep 2010) Log Message: ----------- fix bezier.get_parallerls to handle parallel input lines Modified Paths: -------------- branches/v1_0_maint/lib/matplotlib/bezier.py Modified: branches/v1_0_maint/lib/matplotlib/bezier.py =================================================================== --- branches/v1_0_maint/lib/matplotlib/bezier.py 2010-09-24 01:49:13 UTC (rev 8719) +++ branches/v1_0_maint/lib/matplotlib/bezier.py 2010-09-27 01:30:19 UTC (rev 8720) @@ -9,6 +9,7 @@ from matplotlib.path import Path from operator import xor +import warnings # some functions @@ -323,7 +324,23 @@ d = (dx*dx + dy*dy)**.5 return dx/d, dy/d +def check_if_parallel(dx1, dy1, dx2, dy2, tolerence=1.e-5): + """ returns + * 1 if two lines are parralel in same direction + * -1 if two lines are parralel in opposite direction + * 0 otherwise + """ + theta1 = np.arctan2(dx1, dy1) + theta2 = np.arctan2(dx2, dy2) + dtheta = np.abs(theta1 - theta2) + if dtheta < tolerence: + return 1 + elif np.abs(dtheta - np.pi) < tolerence: + return -1 + else: + return False + def get_parallels(bezier2, width): """ Given the quadraitc bezier control points *bezier2*, returns @@ -338,11 +355,19 @@ cmx, cmy = bezier2[1] c2x, c2y = bezier2[2] - # t1 and t2 is the anlge between c1 and cm, cm, c2. - # They are also a angle of the tangential line of the path at c1 and c2 - cos_t1, sin_t1 = get_cos_sin(c1x, c1y, cmx, cmy) - cos_t2, sin_t2 = get_cos_sin(cmx, cmy, c2x, c2y) + parallel_test = check_if_parallel(c1x-cmx, c1y-cmy, cmx-c2x, cmy-c2y) + if parallel_test == -1: + warnings.warn("Lines do not intersect. A straight line is used instead.") + #cmx, cmy = 0.5*(c1x+c2x), 0.5*(c1y+c2y) + cos_t1, sin_t1 = get_cos_sin(c1x, c1y, c2x, c2y) + cos_t2, sin_t2 = cos_t1, sin_t1 + else: + # t1 and t2 is the anlge between c1 and cm, cm, c2. They are + # also a angle of the tangential line of the path at c1 and c2 + cos_t1, sin_t1 = get_cos_sin(c1x, c1y, cmx, cmy) + cos_t2, sin_t2 = get_cos_sin(cmx, cmy, c2x, c2y) + # find c1_left, c1_right which are located along the lines # throught c1 and perpendicular to the tangential lines of the # bezier path at a distance of width. Same thing for c2_left and @@ -355,11 +380,21 @@ # find cm_left which is the intersectng point of a line through # c1_left with angle t1 and a line throught c2_left with angle # t2. Same with cm_right. - cmx_left, cmy_left = get_intersection(c1x_left, c1y_left, cos_t1, sin_t1, - c2x_left, c2y_left, cos_t2, sin_t2) + if parallel_test != 0: + # a special case for a straight line, i.e., angle between two + # lines are smaller than some (arbitrtay) value. + cmx_left, cmy_left = \ + 0.5*(c1x_left+c2x_left), 0.5*(c1y_left+c2y_left) + cmx_right, cmy_right = \ + 0.5*(c1x_right+c2x_right), 0.5*(c1y_right+c2y_right) + else: + cmx_left, cmy_left = \ + get_intersection(c1x_left, c1y_left, cos_t1, sin_t1, + c2x_left, c2y_left, cos_t2, sin_t2) - cmx_right, cmy_right = get_intersection(c1x_right, c1y_right, cos_t1, sin_t1, - c2x_right, c2y_right, cos_t2, sin_t2) + cmx_right, cmy_right = \ + get_intersection(c1x_right, c1y_right, cos_t1, sin_t1, + c2x_right, c2y_right, cos_t2, sin_t2) # the parralel bezier lines are created with control points of # [c1_left, cm_left, c2_left] and [c1_right, cm_right, c2_right] This was sent by the SourceForge.net collaborative development platform, the world's largest Open Source development site. ```