Merge pull request #44089 from Xrayez/rng-state

Add ability to restore `RandomNumberGenerator` state

3 files changed, 13 insertions, 9 deletions

diff --git a/core/math/random_number_generator.cpp b/core/math/random_number_generator.cpp
index a124f63030..f045213fb9 100644
--- a/core/math/random_number_generator.cpp
+++ b/core/math/random_number_generator.cpp
@@ -34,6 +34,9 @@ void RandomNumberGenerator::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_seed", "seed"), &RandomNumberGenerator::set_seed);
 	ClassDB::bind_method(D_METHOD("get_seed"), &RandomNumberGenerator::get_seed);
 
+	ClassDB::bind_method(D_METHOD("set_state", "state"), &RandomNumberGenerator::set_state);
+	ClassDB::bind_method(D_METHOD("get_state"), &RandomNumberGenerator::get_state);
+
 	ClassDB::bind_method(D_METHOD("randi"), &RandomNumberGenerator::randi);
 	ClassDB::bind_method(D_METHOD("randf"), &RandomNumberGenerator::randf);
 	ClassDB::bind_method(D_METHOD("randfn", "mean", "deviation"), &RandomNumberGenerator::randfn, DEFVAL(0.0), DEFVAL(1.0));
@@ -42,6 +45,8 @@ void RandomNumberGenerator::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("randomize"), &RandomNumberGenerator::randomize);
 
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "seed"), "set_seed", "get_seed");
-	// Default value is non-deterministic, override it for doc generation purposes.
+	ADD_PROPERTY(PropertyInfo(Variant::INT, "state"), "set_state", "get_state");
+	// Default values are non-deterministic, override for doc generation purposes.
 	ADD_PROPERTY_DEFAULT("seed", 0);
+	ADD_PROPERTY_DEFAULT("state", 0);
 }
diff --git a/core/math/random_number_generator.h b/core/math/random_number_generator.h
index 0d0ea17205..7728fd09c0 100644
--- a/core/math/random_number_generator.h
+++ b/core/math/random_number_generator.h
@@ -44,19 +44,17 @@ protected:
 
 public:
 	_FORCE_INLINE_ void set_seed(uint64_t p_seed) { randbase.seed(p_seed); }
-
 	_FORCE_INLINE_ uint64_t get_seed() { return randbase.get_seed(); }
 
+	_FORCE_INLINE_ void set_state(uint64_t p_state) { randbase.set_state(p_state); }
+	_FORCE_INLINE_ uint64_t get_state() const { return randbase.get_state(); }
+
 	_FORCE_INLINE_ void randomize() { randbase.randomize(); }
 
 	_FORCE_INLINE_ uint32_t randi() { return randbase.rand(); }
-
 	_FORCE_INLINE_ real_t randf() { return randbase.randf(); }
-
 	_FORCE_INLINE_ real_t randf_range(real_t p_from, real_t p_to) { return randbase.random(p_from, p_to); }
-
 	_FORCE_INLINE_ real_t randfn(real_t p_mean = 0.0, real_t p_deviation = 1.0) { return randbase.randfn(p_mean, p_deviation); }
-
 	_FORCE_INLINE_ int randi_range(int p_from, int p_to) { return randbase.random(p_from, p_to); }
 
 	RandomNumberGenerator() {}
diff --git a/core/math/random_pcg.h b/core/math/random_pcg.h
index fe6b1b5639..2e257cb5b7 100644
--- a/core/math/random_pcg.h
+++ b/core/math/random_pcg.h
@@ -61,7 +61,7 @@ static int __bsr_clz32(uint32_t x) {
 
 class RandomPCG {
 	pcg32_random_t pcg;
-	uint64_t current_seed; // seed with this to get the same state
+	uint64_t current_seed; // The seed the current generator state started from.
 	uint64_t current_inc;
 
 public:
@@ -76,13 +76,14 @@ public:
 	}
 	_FORCE_INLINE_ uint64_t get_seed() { return current_seed; }
 
+	_FORCE_INLINE_ void set_state(uint64_t p_state) { pcg.state = p_state; }
+	_FORCE_INLINE_ uint64_t get_state() const { return pcg.state; }
+
 	void randomize();
 	_FORCE_INLINE_ uint32_t rand() {
-		current_seed = pcg.state;
 		return pcg32_random_r(&pcg);
 	}
 	_FORCE_INLINE_ uint32_t rand(uint32_t bounds) {
-		current_seed = pcg.state;
 		return pcg32_boundedrand_r(&pcg, bounds);
 	}