diff options
| -rw-r--r-- | core/math/random_pcg.cpp | 12 | ||||
| -rw-r--r-- | tests/test_random_number_generator.h | 20 |
2 files changed, 22 insertions, 10 deletions
diff --git a/core/math/random_pcg.cpp b/core/math/random_pcg.cpp index e0768b9403..c39037747a 100644 --- a/core/math/random_pcg.cpp +++ b/core/math/random_pcg.cpp @@ -51,16 +51,8 @@ float RandomPCG::random(float p_from, float p_to) { } int RandomPCG::random(int p_from, int p_to) { - int range; - int min; - if (p_to > p_from) { - range = p_to - p_from + 1; - min = p_from; - } else if (p_to < p_from) { - range = p_from - p_to + 1; - min = p_to; - } else { // from == to + if (p_from == p_to) { return p_from; } - return rand(range) + min; + return rand(abs(p_from - p_to) + 1) + MIN(p_from, p_to); } diff --git a/tests/test_random_number_generator.h b/tests/test_random_number_generator.h index 900bb55ffd..999e6d4862 100644 --- a/tests/test_random_number_generator.h +++ b/tests/test_random_number_generator.h @@ -250,6 +250,26 @@ TEST_CASE("[RandomNumberGenerator] Restore from seed") { CHECK_MESSAGE(s0_1_before == s0_1_after, msg); CHECK_MESSAGE(s0_2_before == s0_2_after, msg); } + +TEST_CASE_MAY_FAIL("[RandomNumberGenerator] randi_range bias check") { + int zeros = 0; + int ones = 0; + Ref<RandomNumberGenerator> rng = memnew(RandomNumberGenerator); + for (int i = 0; i < 10000; i++) { + int val = rng->randi_range(0, 1); + val == 0 ? zeros++ : ones++; + } + CHECK_MESSAGE(abs(zeros * 1.0 / ones - 1.0) < 0.1, "The ratio of zeros to ones should be nearly 1"); + + int vals[10] = { 0 }; + for (int i = 0; i < 1000000; i++) { + vals[rng->randi_range(0, 9)]++; + } + + for (int i = 0; i < 10; i++) { + CHECK_MESSAGE(abs(vals[i] / 1000000.0 - 0.1) < 0.01, "Each element should appear roughly 10% of the time"); + } +} } // namespace TestRandomNumberGenerator #endif // TEST_RANDOM_NUMBER_GENERATOR_H |