Added override (in gnuplot file) for inside/outside path detection.

- cameo/cameo.c (process_paths): explain the inside/outside path detection
  heuristics
- cameo/path.h (struct path), cameo/path.c (path_new): added attribute
  "outside" to explicitly mark paths as outside edges
- cameo/path.c (path_from): new function to make a path that takes the
  attributes of another path
- cameo/path.c (path_reverse, path_offset): use path_from instead of
  path_new
- cameo/gnuplot.c (gnuplot_read, gnuplot_do_write): read and write the
  #%outside hint

cameo/cameo.c

@@ -37,10 +37,24 @@ static void process_paths(struct path *paths)
 {
 	struct path *leftmost, *path;
 
+	/*
+	 * We don't have an algorithm (yet) that can detect which paths are
+	 * inside other paths. Therefore, we fake it by looking for the path
+	 * that contains lowest x coordinate. This ought to be the outer
+	 * boundary of the piece.
+	 *
+	 * Note that this heuristic falls apart when a job consists of
+	 * multiple pieces. In this case, the #%outside hint can be used to
+	 * explicitly tell cameo to treat the path as an outside edge.
+	 */
+
 	leftmost = path_find_leftmost(paths);
 	for (path = paths; path; path = path->next)
-		if (path != leftmost)
+		if (path != leftmost && !path->outside)
 			process_path(path, 1);
+	for (path = paths; path; path = path->next)
+		if (path != leftmost && path->outside)
+			process_path(path, 0);
 	process_path(leftmost, 0);
 }
 

cameo/gnuplot.c

@@ -13,6 +13,7 @@
 
 #include <stdlib.h>
 #include <stdio.h>
+#include <string.h>
 
 #include "path.h"
 #include "gnuplot.h"
@@ -25,6 +26,7 @@ struct path *gnuplot_read(const char *name, double r_tool_default)
 	char buf[1024];
 	double x, y, z, tmp;
 	double r_tool = r_tool_default;
+	int outside = 0;
 	int n;
 	struct path *paths = NULL, *path = NULL;
 	struct path **lnk = &paths;
@@ -39,6 +41,8 @@ struct path *gnuplot_read(const char *name, double r_tool_default)
 		lineno++;
 		if (sscanf(buf, "#%%r_tool=%lf\n", &tmp) == 1)
 			r_tool = tmp;
+		if (!strcmp(buf, "#%outside\n"))
+			outside = 1;
 		if (*buf == '#')
 			continue;
 		n = sscanf(buf, "%lf %lf %lf\n", &x, &y, &z);
@@ -46,6 +50,7 @@ struct path *gnuplot_read(const char *name, double r_tool_default)
 		case -1:
 			path = NULL;
 			r_tool = r_tool_default;
+			outside = 0;
 			continue;
 		case 2:
 			z = 0;
@@ -60,6 +65,7 @@ struct path *gnuplot_read(const char *name, double r_tool_default)
 
 		if (!path) {
 			path = path_new(r_tool);
+			path->outside = outside;
 			*lnk = path;
 			lnk = &path->next;
 		}
@@ -81,6 +87,8 @@ static int gnuplot_do_write(FILE *file, const struct path *paths)
 				return 0;
 		if (fprintf(file, "#%%r_tool=%f\n", path->r_tool) < 0)
 			return 0;
+		if (path->outside && fprintf(file, "#%%outside\n") < 0)
+			return 0;
 		for (p = path->first; p; p = p->next)
 			if (fprintf(file, "%f %f %f\n", p->x, p->y, p->z) < 0)
 				return 0;

cameo/path.c

@@ -45,12 +45,23 @@ struct path *path_new(double r_tool)
 
 	path = alloc_type(struct path);
 	path->r_tool = r_tool;
+	path->outside = 0;
 	path->first = path->last = NULL;
 	path->next = NULL;
 	return path;
 }
 
 
+static struct path *path_from(const struct path *old)
+{
+	struct path *new;
+
+	new = path_new(old->r_tool);
+	new->outside = old->outside;
+	return new;
+}
+
+
 static struct point *clone_point(struct point *p)
 {
 	struct point *n;
@@ -113,7 +124,7 @@ struct path *path_reverse(const struct path *path)
 	const struct point *p;
 	struct point *n;
 
-	new = path_new(path->r_tool);
+	new = path_from(path);
 	for (p = path->first; p; p = p->next) {
 		n = alloc_type(struct point);
 		n->x = p->x;
@@ -275,7 +286,7 @@ struct path *path_offset(const struct path *path, int left, int notch)
 	int dog;
 
 	assert(path_is_closed(path));
-	new = path_new(path->r_tool);
+	new = path_from(path);
 	prev = path->first;
 	for (p = path->first->next; p; p = p->next) {
 		next = p->next ? p->next : path->first->next;

cameo/path.h

@@ -23,6 +23,7 @@ struct point {
 struct path {
 	struct point *first, *last;
 	double r_tool;	/* mm */
+	int outside;	/* non-zero to mark path as an outside edge */
 	struct path *next;
 };