work in progress
in the middle of switching to sortless version
git-svn-id: http://skia.googlecode.com/svn/trunk@3768 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/experimental/Intersection/LineUtilities.cpp b/experimental/Intersection/LineUtilities.cpp
index 1394225..38e1ba0 100644
--- a/experimental/Intersection/LineUtilities.cpp
+++ b/experimental/Intersection/LineUtilities.cpp
@@ -30,3 +30,28 @@
dst[1].x = line[0].x - t2 * delta.x;
dst[1].y = line[0].y - t2 * delta.y;
}
+
+// may have this below somewhere else already:
+// copying here because I thought it was clever
+
+// Copyright 2001, softSurfer (www.softsurfer.com)
+// This code may be freely used and modified for any purpose
+// providing that this copyright notice is included with it.
+// SoftSurfer makes no warranty for this code, and cannot be held
+// liable for any real or imagined damage resulting from its use.
+// Users of this code must verify correctness for their application.
+
+// Assume that a class is already given for the object:
+// Point with coordinates {float x, y;}
+//===================================================================
+
+// isLeft(): tests if a point is Left|On|Right of an infinite line.
+// Input: three points P0, P1, and P2
+// Return: >0 for P2 left of the line through P0 and P1
+// =0 for P2 on the line
+// <0 for P2 right of the line
+// See: the January 2001 Algorithm on Area of Triangles
+float isLeft( _Point P0, _Point P1, _Point P2 )
+{
+ return (P1.x - P0.x)*(P2.y - P0.y) - (P2.x - P0.x)*(P1.y - P0.y);
+}