Index: erode.c
===================================================================
--- erode.c	(revision 7413)
+++ erode.c	(revision 7414)
@@ -9,7 +9,6 @@
 
 #include "pcb_draw.h"
 
-
 int stat[100];
 
 static inline void ray(image_t *i, double x, double y, double dx, double dy, int *out)
@@ -44,6 +43,60 @@
 	return h;
 }
 
+static int near(int *hg, int my, double cx, double cy, int width, int clear)
+{
+	int x1 = round(cx - 1), x2 = round(cx + 1);
+	int y1 = round(cy - 1), y2 = round(cy + 1);
+	int x, y;
+	for(y = y1; y <= y2; y++) {
+		for(x = x1; x <= x2; x++) {
+			if (hg[x + y*width] == my) {
+				if (clear)
+					hg[x + y*width] = 0;
+				return 1;
+			}
+		}
+	}
+	return 0;
+}
+
+static int find_line(image_t *trace, int *hg, int my, int cx, int cy, double ang, int width)
+{
+	double dx, dy, x, y, ex, ey;
+	int len = -2;
+
+	dx = cos(ang);
+	dy = sin(ang);
+	x = cx;
+	y = cy;
+	do {
+		len++;
+		x += dx;
+		y += dy;
+		if (trace != NULL) {
+			image_pix(trace, (int)round(x), (int)round(y)) = pixel_blue;
+			hg[(int)round(x) + (int)round(y) * width] = 0;
+		}
+	} while(near(hg, my, x, y, width, trace != NULL));
+	ex = x;
+	ey = y;
+	x = cx;
+	y = cy;
+	do {
+		len++;
+		x -= dx;
+		y -= dy;
+		if (trace != NULL) {
+			image_pix(trace, (int)round(x), (int)round(y)) = pixel_blue;
+			hg[(int)round(x) + (int)round(y) * width] = 0;
+		}
+	} while(near(hg, my, x, y, width, trace != NULL));
+	if (trace != NULL) {
+		printf("stroke %d %d %d %d\n", (int)round(ex), (int)round(ey), (int)round(x), (int)round(y));
+	}
+	return len;
+}
+
 int main(int arc, char *argv[])
 {
 	image_t *ref;
@@ -50,7 +103,7 @@
 	int *hg;
 	int maxh = 0;
 	int x, y, n, cutoff, end;
-	char *ref_fn = "1.pnm";
+	char *ref_fn = "l.pnm";
 
 	if (argv[1] != NULL)
 		ref_fn = argv[1];
@@ -57,6 +110,7 @@
 
 	ref = pnm_load(ref_fn);
 
+	/* height map */
 	hg = calloc(sizeof(int), ref->sx * ref->sy);
 	for(y = 1; y < ref->sy-1; y++) {
 		for(x = 1; x < ref->sy-1; x++) {
@@ -81,8 +135,9 @@
 	printf("-- cutoff=%d\n", cutoff);
 	end = ref->sx * ref->sy;
 	for(n = 0; n < end; n++) {
-		if (hg[n] == cutoff)
+		if (hg[n] == cutoff) {
 			ref->pixmap[n] = pixel_red;
+		}
 		else if (ref->pixmap[n].r != 255) {
 			ref->pixmap[n].r = 200;
 			ref->pixmap[n].g = 200;
@@ -89,6 +144,35 @@
 			ref->pixmap[n].b = 200;
 		}
 	}
+
+
+	/* brute force lines */
+	for(;;) {
+		int best_len = 0, bestx, besty;
+		double besta;
+		for(n = 0; n < end; n++) {
+			if (hg[n] == cutoff) {
+				double a;
+				int x, y;
+				x = image_x(ref, ref->pixmap+n);
+				y = image_y(ref, ref->pixmap+n);
+				for(a = 0; a < M_PI; a+=0.1) {
+					int len = find_line(NULL, hg, cutoff, x, y, a, ref->sx);
+					if (len > best_len) {
+						best_len = len;
+						bestx = x;
+						besty = y;
+						besta = a;
+					}
+				}
+			}
+		}
+		if (best_len <= cutoff*3)
+			break;
+		printf("len=%d\n", best_len);
+		find_line(ref, hg, cutoff, bestx, besty, besta, ref->sx);
+	}
+
 	pnm_save(ref, "OUT.pnm");
 }