Fixed steepest_neighbor (return type was wrong).

.gitignore

@@ -2,3 +2,4 @@ seamless
 image.jpg
 *~
 *.swp
+*.o

Makefile

@@ -1,2 +1,28 @@
-seamless: main.c energy_functions.c pixel_access.c array_image.c
-	gcc -Wall -Werror -pedantic-errors -std=c99 `sdl-config --cflags --libs` -lSDL_image energy_functions.c pixel_access.c array_image.c main.c -o seamless -O3
+OBJS = main.o array_image.o energy_functions.o pixel_access.o
+
+CFLAGS = -c -Wall -Werror -pedantic-errors -std=c99 -O3
+ifeq ($(DEBUG),1)
+  CFLAGS += -g
+endif
+
+CFLAGS += `sdl-config --cflags`
+LIBS = `sdl-config --libs` -lSDL_image
+
+seamless: $(OBJS)
+	gcc $(LIBS) $(OBJS) -o seamless
+
+main.o: main.c array_image.h util.h
+	gcc $(CFLAGS) main.c
+
+array_image.o: array_image.c array_image.h pixel_access.h
+	gcc $(CFLAGS) array_image.c
+
+energy_functions.o: energy_functions.c util.h array_image.h
+	gcc $(CFLAGS) energy_functions.c
+
+pixel_access.o: pixel_access.c pixel_access.h
+	gcc $(CFLAGS) pixel_access.c
+
+clean:
+	rm -f $(OBJS)
+	rm seamless

energy_functions.c

@@ -64,7 +64,7 @@ gradient_magnitude (Uint8 * image, int w, int h, int x, int y)
   return sqrt (ddx * ddx + ddy * ddy);
 }
 
-Uint8
+float
 steepest_neighbor (Uint8 * image, int w, int h, int x, int y)
 {
   Uint8 l, l1, l2, l3, l4, l5, l6, l7, l8;
@@ -92,29 +92,27 @@ steepest_neighbor (Uint8 * image, int w, int h, int x, int y)
   if (y > 0)
     {
       pixel = array_p (image, w, x, y - 1);
-      l1 = abs (l - value_from_rgb (pixel[0], pixel[1], pixel[2]));
+      l4 = abs (l - value_from_rgb (pixel[0], pixel[1], pixel[2]));
     }
-  pixel = array_p (image, w, x, y);
-  l2 = abs (l - value_from_rgb (pixel[0], pixel[1], pixel[2]));
   if (y < h - 1)
     {
       pixel = array_p (image, w, x, y + 1);
-      l3 = abs (l - value_from_rgb (pixel[0], pixel[1], pixel[2]));
+      l5 = abs (l - value_from_rgb (pixel[0], pixel[1], pixel[2]));
     }
 
   if (x < w - 1)
     {
       if (y > 0)
         {
           pixel = array_p (image, w, x + 1, y - 1);
-          l1 = abs (l - value_from_rgb (pixel[0], pixel[1], pixel[2]));
+          l6 = abs (l - value_from_rgb (pixel[0], pixel[1], pixel[2]));
         }
       pixel = array_p (image, w, x + 1, y);
-      l2 = abs (l - value_from_rgb (pixel[0], pixel[1], pixel[2]));
+      l7 = abs (l - value_from_rgb (pixel[0], pixel[1], pixel[2]));
       if (y < h - 1)
         {
           pixel = array_p (image, w, x + 1, y + 1);
-          l3 = abs (l - value_from_rgb (pixel[0], pixel[1], pixel[2]));
+          l8 = abs (l - value_from_rgb (pixel[0], pixel[1], pixel[2]));
         }
     }
 

main.c

@@ -5,7 +5,6 @@
 #include <SDL_image.h>
 
 #include "util.h"
-#include "pixel_access.h"
 #include "array_image.h"
 
 
@@ -109,7 +108,7 @@ main (int argc, char *argv[])
   int running = 1;
   Uint32 black = SDL_MapRGB (screen->format, 0, 0, 0);
   SDL_Event event;
-  energy_function f = gradient_magnitude;
+  energy_function f = steepest_neighbor;
   SDL_Surface *energy = energize (image, f);
   while (running)
     {