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Torque/SDK/lib/maxsdk40/random.h

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+/**********************************************************************
+ *<
+        FILE: random.h
+
+        DESCRIPTION: Pseudo-random number generator
+
+        CREATED BY: Jeff Kowalski
+
+        HISTORY: Created 11 February 1999
+
+ *>     Copyright (c) 1999, All Rights Reserved.
+ **********************************************************************/
+
+#ifndef __RANDOM__H
+#define __RANDOM__H
+
+/*
+ * This class defines a Pseudo-random number generator that precisely
+ * matches the behavior of the MSVCRT 6.0 random routines.
+ * That is to say, for equivalent calls to ::srand() and Random::srand(),
+ * both ::rand() and Random::rand() will produce the same results.
+ *
+ * The benefit, however, in having this class is that each instantiation
+ * is independent, permitting several uncoupled random number generators
+ * to be present in the system at once.  Moreover, each instantiation
+ * is automatically "pre-seeded", making calls to Random::srand unnecessary
+ * in most uses.  Even arrays of Random items will operate independently.
+ *
+ * In addition to providing the analogues to the "stdlib" functions, this
+ * class also provides two useful member functions which can be used
+ * to get a random number bounded in either a float or int interval.
+ */
+class Random {
+    private:
+        long   m_seed;
+
+    public:
+        // The constructor will automatically initialize the seed
+        UtilExport Random ();
+
+        // Analogues of the random rountines from MSVCRT:
+        UtilExport void    srand (unsigned int seed = 1); // akin to global ::srand
+        UtilExport int     rand  ();                      // akin to global ::rand
+        UtilExport static const int s_rand_max;           // akin to global RAND_MAX
+
+        // Returns a random number in the half-open interval [min, max)
+        //      such that r=get(max, min)  :=  min <= r < max
+        // Note that max is the first arg, and min is the second, permitting
+        // one to select, for example, an int in [0,5) = [0,4] with "get(5)"
+        // With no arguments, Random::get() is equivalent to Random::rand()
+        inline int   get  (int   max_exclusive = s_rand_max+1,
+                           int   min_inclusive = 0) {
+            return this->rand() %
+                     (max_exclusive - min_inclusive) + min_inclusive;
+        }
+
+        // Returns a random number in the half-open interval [min, max)
+        //      such that r=get(max, min)  :=  min <= r < max
+        // Note that max is the first arg, and min is the second, permitting
+        // one to select, for example, a float in [0.0, 5.0) with "getf(5)"
+        // With no arguments, Random::getf() returns a float in [0.0, 1.0)
+        inline float getf (float max_exclusive = 1.0f,
+                           float min_inclusive = 0.0f) {
+            return this->rand() / (s_rand_max+1.0f) *
+                     (max_exclusive - min_inclusive) + min_inclusive;
+        }
+};
+
+#endif // __RANDOM__H