From 82eb7e49739c2cecf601f5fd15797301aa4d7e1b Mon Sep 17 00:00:00 2001
From: Hannes Janetzek <hannes.janetzek@gmail.com>
Date: Thu, 10 Jan 2013 06:57:42 +0100
Subject: [PATCH] more line intersection utilities
---
src/org/oscim/utils/GeometryUtils.java | 39 ++++++++++++++++++++++++++
1 file changed, 39 insertions(+)
diff --git a/src/org/oscim/utils/GeometryUtils.java b/src/org/oscim/utils/GeometryUtils.java
index 3e52e719..9812f607 100644
--- a/src/org/oscim/utils/GeometryUtils.java
+++ b/src/org/oscim/utils/GeometryUtils.java
@@ -185,4 +185,43 @@ public final class GeometryUtils {
return Math.abs((P.x - A.x) * (B.y - A.y) - (P.y - A.y) * (B.x - A.x)) / normalLength;
}
+ public static final class Point2D {
+ public double x;
+ public double y;
+ }
+
+ // from libosmscout-render
+ public static byte calcLinesIntersect(
+ double ax1, double ay1,
+ double ax2, double ay2,
+ double bx1, double by1,
+ double bx2, double by2,
+ GeometryUtils.Point2D point)
+ {
+ double ua_numr = (bx2 - bx1) * (ay1 - by1) - (by2 - by1) * (ax1 - bx1);
+ double ub_numr = (ax2 - ax1) * (ay1 - by1) - (ay2 - ay1) * (ax1 - bx1);
+ double denr = (by2 - by1) * (ax2 - ax1) - (bx2 - bx1) * (ay2 - ay1);
+
+ if (denr == 0.0)
+ {
+ // lines are coincident
+ if (ua_numr == 0.0 && ub_numr == 0.0)
+ return 2; //XSEC_COINCIDENT;
+
+ // lines are parallel
+ return 3; //XSEC_PARALLEL;
+ }
+
+ double ua = ua_numr / denr;
+ double ub = ub_numr / denr;
+
+ //if (ua >= 0.0 && ua <= 1.0 && ub >= 0.0 && ub <= 1.0)
+ {
+ point.x = ax1 + ua * (ax2 - ax1);
+ point.y = ay1 + ua * (ay2 - ay1);
+ return 0; //XSEC_TRUE;
+ }
+
+ //return 1; //XSEC_FALSE;
+ }
}