Subject: [Boost-commit] svn:boost r73371 - trunk/boost/polygon
From: lucanus.j.simonson_at_[hidden]
Date: 2011-07-25 22:51:43
Author: ljsimons
Date: 2011-07-25 22:51:42 EDT (Mon, 25 Jul 2011)
New Revision: 73371
URL: http://svn.boost.org/trac/boost/changeset/73371
Log:
fix for euclidean distance from point to line segment
Text files modified:
trunk/boost/polygon/directed_line_segment_concept.hpp | 22 ++++++++--------------
1 files changed, 8 insertions(+), 14 deletions(-)
Modified: trunk/boost/polygon/directed_line_segment_concept.hpp
==============================================================================
--- trunk/boost/polygon/directed_line_segment_concept.hpp (original)
+++ trunk/boost/polygon/directed_line_segment_concept.hpp 2011-07-25 22:51:42 EDT (Mon, 25 Jul 2011)
@@ -303,19 +303,6 @@
euclidean_distance(const segment_type& segment,
typename directed_line_segment_traits<segment_type>::point_type position) {
typedef typename directed_line_segment_distance_type<segment_type>::type Unit;
- Unit result1 = euclidean_distance(low(segment), high(segment));
- Unit result2 = euclidean_distance(low(segment), position);
- Unit result3 = euclidean_distance(high(segment), position);
- if(result2 > result1) {
- if(result3*result3 < result2*result2 - result1*result1)
- return result3;
- }
- else if(result3 > result1) {
- if(result2*result2 < result3*result3 - result1*result1)
- return result2;
- }
- if(on_above_or_below(segment, position) == 0)
- return 0.0; //I don't want to return non-zero distance if the predicate returns on the line
Unit x1 = x(low(segment));
Unit y1 = y(low(segment));
Unit x2 = x(high(segment));
@@ -326,7 +313,14 @@
Unit B = Y - y1;
Unit C = x2 - x1;
Unit D = y2 - y1;
- Unit denom = sqrt(C * C + D * D);
+ Unit length_sq = C * C + D * D;
+ Unit param = (A * C + B * D)/length_sq;
+ if(param > 1.0) {
+ return euclidean_distance(high(segment), position);
+ } else if(param < 0.0) {
+ return euclidean_distance(low(segment), position);
+ }
+ Unit denom = sqrt(length_sq);
if(denom == 0.0)
return 0.0;
Unit result = (A * D - C * B) / denom;