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Fix PRNG randomization.

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PCG32 doesn't like small seeds, which leads to zero random values (prior to #7532, zero values were handled as special cases).

Use a large default seed, and also add a shift in Math::randomize.

Fixes #8423.
This commit is contained in:
Ferenc Arn 2017-04-17 12:50:31 -05:00
parent 6f9ec3acfc
commit ceb699f5ec
3 changed files with 3 additions and 6 deletions
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6
core/math/math_funcs.cpp
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@ -30,7 +30,7 @@
#include "math_funcs.h" #include "math_funcs.h"
#include "core/os/os.h" #include "core/os/os.h"
pcg32_random_t Math::default_pcg = { 1, PCG_DEFAULT_INC_64 }; pcg32_random_t Math::default_pcg = { 12047754176567800795ULL, PCG_DEFAULT_INC_64 };
#define PHI 0x9e3779b9 #define PHI 0x9e3779b9
@ -51,9 +51,7 @@ void Math::seed(uint64_t x) {
} }
void Math::randomize() { void Math::randomize() {
seed(OS::get_singleton()->get_ticks_usec() * default_pcg.state + PCG_DEFAULT_INC_64);
OS::Time time = OS::get_singleton()->get_time();
seed(OS::get_singleton()->get_ticks_usec() * (time.hour + 1) * (time.min + 1) * (time.sec + 1) * rand()); // TODO: can be simplified.
} }
uint32_t Math::rand() { uint32_t Math::rand() {

2
core/math/math_funcs.h
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@ -157,7 +157,7 @@ public:
static uint32_t larger_prime(uint32_t p_val); static uint32_t larger_prime(uint32_t p_val);
static void seed(uint64_t x = 0); static void seed(uint64_t x);
static void randomize(); static void randomize();
static uint32_t rand_from_seed(uint64_t *seed); static uint32_t rand_from_seed(uint64_t *seed);
static uint32_t rand(); static uint32_t rand();

1
core/os/os.cpp
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@ -507,7 +507,6 @@ OS::OS() {
_render_thread_mode = RENDER_THREAD_SAFE; _render_thread_mode = RENDER_THREAD_SAFE;
_allow_hidpi = true; _allow_hidpi = true;
Math::seed(1234567);
} }
OS::~OS() { OS::~OS() {