[gegl] gegl:perlin-noise: use a local random generator for initializing

[Øyvind "pippin" Kolås <ok src gnome org>]

commit 8fbdf0c5637a7e7c72db944982c5afd0c1b9ceb6
Author: Tatsuki Makino <tatsuki_makino hotmail com>
Date:   Thu Jul 30 11:43:35 2020 +0200

    gegl:perlin-noise: use a local random generator for initializing
    
    Settin gthe global seed with g_random_set_seed impacts programs
    using GEGL, for instance the random splash feature in GIMP had
    become deterministic.

 operations/common/perlin/perlin.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/operations/common/perlin/perlin.c b/operations/common/perlin/perlin.c
index 400c27183..9d3882930 100644
--- a/operations/common/perlin/perlin.c
+++ b/operations/common/perlin/perlin.c
@@ -7,7 +7,7 @@
 #include "perlin.h"
 
 /* random is not portable to all platforms */
-#define random g_random_int
+#define random() g_rand_int (gr)
 
 static int p[B + B + 2];
 static double g3[B + B + 2][3];
@@ -150,8 +150,7 @@ perlin_init (void)
   if (initialized)
     return;
   /* this is racy - but we call it once when creating our perlin noise op */
-
-  g_random_set_seed (1234567890);
+  GRand *gr = g_rand_new_with_seed (1234567890);
 
   for (i = 0; i < B; i++)
     {
@@ -184,6 +183,7 @@ perlin_init (void)
         g3[B + i][j] = g3[i][j];
     }
   initialized = 1;
+  g_rand_free (gr);
 }
 
 /* --- My harmonic summing functions - PDB --------------------------*/