Control inclination of the z0 plane. (Needs more work.)

- solidify/face.h (struct face), solidify/face.c (read_face),
  solidify/level.c (draw_map, draw_image): introduce inclination of the z0
  plane
- solidify/level.c (draw_map): make blue z == z0 display more continuous
- solidify/level.c (scroll_event): moved z0 shift to scroll_z
- solidify/level.c (scroll_event, scroll_xy): added manipulation of the
  z0 plane's inclination

solidify/face.c

@@ -58,6 +58,8 @@ struct face *read_face(const char *name)
 	h = make_histo(f->a);
 	f->z_ref = f->a->min_z+median(h);
 	free_histo(h);
+	f->fx = f->fy = 0;
+
 	fprintf(stderr, "%d-%d / %d-%d / %d-%d\n",
 	    f->a->min_x, f->a->max_x, f->a->min_y, f->a->max_y,
 	    f->a->min_z, f->a->max_z);

solidify/face.h

@@ -6,8 +6,9 @@
 
 struct face {
 	struct array *a;
-	int sx, sy;
+	int sx, sy;	/* size */
 	int z_ref;
+	double fx, fy;	/* inclination factor */
 };
 
 

solidify/level.c

@@ -1,5 +1,6 @@
 #include <stdlib.h>
 #include <stdio.h>
+#include <math.h>
 #include <gtk/gtk.h>
 
 #include "array.h"
@@ -10,6 +11,7 @@
 static void draw_map(GtkWidget *widget, struct face *f)
 {
 	int x, y, z;
+	double z0;
 	guchar *rgbbuf, *p;
 
 	rgbbuf = p = calloc(f->sx*f->sy, 3);
@@ -24,19 +26,20 @@ static void draw_map(GtkWidget *widget, struct face *f)
 				p += 3;
 				continue;
 			}
-			if (z == f->z_ref) {
+			z0 = f->z_ref+f->fx*(x-f->sx/2)+f->fy*(y-f->sy/2);
-				*p++ = 0;
+			if (fabs(z-z0) < 1) {
-				*p++ = 0;
+				*p++ = 255*fabs(z-z0);
+				*p++ = 255*fabs(z-z0);
 				*p++ = 255;
 				continue;
 			}
-			if (z < f->z_ref) {
+			if (z < z0) {
-				z = 255.0*(z-f->z_ref)/(f->z_ref-f->a->min_z);
+				z = 255.0*(z-z0)/(z0-f->a->min_z);
 				*p++ = 255;
 				*p++ = z;
 				*p++ = z;
 			} else {
-				z = 255.0*(f->z_ref-z)/(f->a->max_z-f->z_ref);
+				z = 255.0*(z0-z)/(f->a->max_z-z0);
 				*p++ = z;
 				*p++ = 255;
 				*p++ = z;
@@ -51,29 +54,56 @@ static void draw_map(GtkWidget *widget, struct face *f)
 
 static void draw_image(GtkWidget *da, struct face *f)
 {
-	fprintf(stderr, "%d\n", f->z_ref);
+	fprintf(stderr, "%d %g %g\n", f->z_ref, f->fx, f->fy);
 	draw_map(da, f);
 }
 
 
+static void scroll_z(GtkWidget *da, struct face *f, int up)
+{
+	if (up) {
+		if (f->z_ref < f->a->max_z)
+			f->z_ref++;
+	} else {
+		if (f->z_ref > f->a->min_z)
+			f->z_ref--;
+	}
+	draw_image(da, f);
+}
+
+
+static void scroll_xy(GtkWidget *da, struct face *f, int dx, int dy, int up)
+{
+	double d;
+
+	d = (double) (up ? 1 : -1)/(dx*dx+dy*dy)/2.0;
+	f->fx += d*dx;
+	f->fy += d*dy;
+	draw_image(da, f);
+}
+
+
 static gboolean scroll_event(GtkWidget *widget, GdkEventScroll *event,
     gpointer data)
 {
 	GtkWidget *da = gtk_bin_get_child(GTK_BIN(widget));
 	struct face *f = data;
+	int dx = event->x-f->sx/2;
+	int dy = event->y-f->sy/2;
+	int center = hypot(dx, dy)/hypot(f->sx, f->sy) < 0.25;
 
 	switch (event->direction) {
 	case GDK_SCROLL_UP:
-		if (f->z_ref > f->a->min_z) {
+		if (center)
-			f->z_ref--;
+			scroll_z(da, f, 0);
-			draw_image(da, f);
+		else
-		}
+			scroll_xy(da, f, dx, dy, 1);
 		break;
 	case GDK_SCROLL_DOWN:
-		if (f->z_ref < f->a->max_z) {
+		if (center)
-			f->z_ref++;
+			scroll_z(da, f, 1);
-			draw_image(da, f);
+		else
-		}
+			scroll_xy(da, f, dx, dy, 0);
 		break;
 	default:
 		/* ignore */;