Add a seed function that gives the same random seed within a ten minute period of time. This should be useful for synchronizing display systems.

simgear/math/sg_random.c

@@ -134,6 +134,13 @@ void sg_srandom_time() {
     init_genrand(time(NULL));
 }
 
+// Seed the random number generater with time() in 10 minute intervals
+// so we get the same sequence within 10 minutes interval.
+// This is useful for synchronizing two display systems.
+void sg_srandom_time_10() {
+    init_genrand(time(NULL) / 600);
+}
+
 
 // Seed the random number generater with your own seed so can set up
 // repeatable randomization.

simgear/math/sg_random.h

@@ -40,6 +40,13 @@ extern "C" {
  */
 void sg_srandom_time();
 
+/**
+ * Seed the random number generater with time() in 10 minute intervals
+ * so we get the same sequence within 10 minutes interval.
+ * This is useful for synchronizing two display systems.
+ */
+void sg_srandom_time_10();
+
 /**
  * Seed the random number generater with your own seed so can set up
  * repeatable randomization.