From a950c5b13cf485393499875c9af8b068eebfa5f2 Mon Sep 17 00:00:00 2001
From: Werner Almesberger <werner@almesberger.net>
Date: Mon, 7 May 2012 22:45:39 -0300
Subject: [PATCH] poly2d/: simplify semantics of first/next offset in area fill

---
 poly2d/README             |  1 -
 poly2d/p2d_area.c         |  4 ++--
 poly2d/p2d_area_holes.cpp | 16 ++++++++--------
 poly2d/poly2d.h           |  6 +++---
 poly2d/test/area          |  6 +++---
 5 files changed, 16 insertions(+), 17 deletions(-)

diff --git a/poly2d/README b/poly2d/README
index 406a9ed..9b0418d 100644
--- a/poly2d/README
+++ b/poly2d/README
@@ -43,7 +43,6 @@ Not yet specified:
 Other:
 - change the license from GPL to LGPL
 - transform CGAL's idea of outer polygons into something we can use
-- use more meaningful offset/overlap model for area fill
 - check for memory leaks
 - try to generate dependencies also for *.cpp
 
diff --git a/poly2d/p2d_area.c b/poly2d/p2d_area.c
index 36695e8..bc45a66 100644
--- a/poly2d/p2d_area.c
+++ b/poly2d/p2d_area.c
@@ -32,13 +32,13 @@ static void recurse_area(struct p2d_hier *t, double offset, double overlap,
 }
 
 
-struct p2d *p2d_area(const struct p2d *p, double offset, double overlap)
+struct p2d *p2d_area(const struct p2d *p, double first, double next)
 {
 	struct p2d_hier *t;
 	struct p2d *res = NULL, **last = &res;
 
 	t = p2d_hsort(p);
-	recurse_area(t, offset, overlap, &last);
+	recurse_area(t, first, next, &last);
 	p2d_hier_free(t);
 	return res;
 }
diff --git a/poly2d/p2d_area_holes.cpp b/poly2d/p2d_area_holes.cpp
index 414a2e0..7118766 100644
--- a/poly2d/p2d_area_holes.cpp
+++ b/poly2d/p2d_area_holes.cpp
@@ -52,17 +52,17 @@ static void append_poly(Polygon_2 poly, struct p2d ***last)
 }
 
 
-static void recurse_area(Polygon_with_holes poly, double curr_off,
-    double next_off, struct p2d ***last)
+static void recurse_area(Polygon_with_holes poly, double current,
+    double next, struct p2d ***last)
 {
 	PolygonPtrVector tmp = 
 	    CGAL::create_interior_skeleton_and_offset_polygons_with_holes_2(
-	    curr_off, poly);
+	    current, poly);
 
 	for (PolygonPtrVector::const_iterator pit = tmp.begin();
 	    pit != tmp.end(); ++pit) {
 		append_poly((*pit)->outer_boundary(), last);
-		recurse_area(**pit, next_off, next_off, last);
+		recurse_area(**pit, next, next, last);
 
 		for (Polygon_with_holes::Hole_const_iterator
 		    hit = (*pit)->holes_begin();
@@ -74,7 +74,7 @@ static void recurse_area(Polygon_with_holes poly, double curr_off,
 
 
 extern "C" void p2d_area_holes_append(const struct p2d *p,
-    const struct p2d *holes, double offset, double overlap,
+    const struct p2d *holes, double first, double next,
     struct p2d ***last)
 {
 	const struct p2d *h;
@@ -87,15 +87,15 @@ extern "C" void p2d_area_holes_append(const struct p2d *p,
 		poly.add_hole(p2d_to_P2(h, 0));
 	}
 
-	recurse_area(poly, offset, offset-overlap, last);
+	recurse_area(poly, first, next, last);
 }
 
 
 extern "C" struct p2d *p2d_area_holes(const struct p2d *p,
-    const struct p2d *holes, double offset, double overlap)
+    const struct p2d *holes, double first, double next)
 {
 	struct p2d *res = NULL, **last = &res;
 
-	p2d_area_holes_append(p, holes, offset, overlap, &last);
+	p2d_area_holes_append(p, holes, first, next, &last);
 	return res;
 }
diff --git a/poly2d/poly2d.h b/poly2d/poly2d.h
index 72281ff..fec85ff 100644
--- a/poly2d/poly2d.h
+++ b/poly2d/poly2d.h
@@ -127,11 +127,11 @@ struct p2d *p2d_offset_holes(const struct p2d *p, const struct p2d *holes,
 struct p2d *p2d_offset(const struct p2d *p, double off);
 
 void p2d_area_holes_append(const struct p2d *p,
-    const struct p2d *holes, double offset, double overlap,
+    const struct p2d *holes, double first, double next,
     struct p2d ***last);
 struct p2d *p2d_area_holes(const struct p2d *p, const struct p2d *holes,
-    double offset, double overlap);
-struct p2d *p2d_area(const struct p2d *p, double offset, double overlap);
+    double first, double next);
+struct p2d *p2d_area(const struct p2d *p, double first, double next);
 
 struct p2d *p2d_read_gnuplot(FILE *file);
 int p2d_write_gnuplot(FILE *file, const struct p2d *p);
diff --git a/poly2d/test/area b/poly2d/test/area
index 2517793..8485f91 100755
--- a/poly2d/test/area
+++ b/poly2d/test/area
@@ -12,7 +12,7 @@ p2d_append(p, v2d_new(5.5, 0));
 p2d_append(p, v2d_new(5.5, 4.5));
 p2d_append(p, v2d_new(0, 4.5));
 p2d_close(p);
-q = p2d_area(p, 1, 0);
+q = p2d_area(p, 1, 1);
 p2d_write_gnuplot_all(stdout, q);
 EOF
 
@@ -42,7 +42,7 @@ p2d_append(p, v2d_new(5.5, 0));
 p2d_append(p, v2d_new(5.5, 4.5));
 p2d_append(p, v2d_new(0, 4.5));
 p2d_close(p);
-q = p2d_area(p, 1, 0.3);
+q = p2d_area(p, 1, 0.7);
 p2d_write_gnuplot_all(stdout, q);
 EOF
 
@@ -81,7 +81,7 @@ p2d_append(p, v2d_new(18, 8));
 p2d_append(p, v2d_new(18, 2));
 p2d_close(p);
 
-q = p2d_area(pl, 0.7, 0);
+q = p2d_area(pl, 0.7, 0.7);
 p2d_write_gnuplot_all(stdout, q);
 EOF