wave.c: better behaviour around image edges.

git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/libpipi/trunk@3403 92316355-f0b4-4df1-b90c-862c8a59935f

pipi/filter/wave.c

@@ -58,12 +58,19 @@ pipi_image_t *pipi_wave(pipi_image_t *src, double freq, double phase,
         {
             double t = cost * (x - w / 2) + sint * (y - h / 2);
             double step = sin(t * freq + phase);
-            double dx = xamp * step;
-            double dy = yamp * step;
+            double dx = xamp;
+            double dy = yamp;
+            int x2, y2;
 
-            int x2 = x + dx;
-            int y2 = y + dy;
+            if(x < 32) dx = dx * x / 32;
+            if(x > w - 1 - 32) dx = dx * (w - 1 - x) / 32;
+            if(y < 32) dy = dy * y / 32;
+            if(y > h - 1 - 32) dy = dy * (h - 1 - y) / 32;
 
+            x2 = x + dx * step;
+            y2 = y + dy * step;
+
+            /* Just in case... */
             if(x2 < 0) x2 = 0;
             else if(x2 >= w) x2 = w - 1;