4c9004671a
PCG is better than many alternatives by many metrics (see www.pcg-random.org) including statistical quality with good speed.
221 lines
5 KiB
C++
221 lines
5 KiB
C++
/*************************************************************************/
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/* math_funcs.cpp */
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/*************************************************************************/
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/* This file is part of: */
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/* GODOT ENGINE */
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/* http://www.godotengine.org */
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/*************************************************************************/
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/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur. */
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/* */
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/* Permission is hereby granted, free of charge, to any person obtaining */
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/* a copy of this software and associated documentation files (the */
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/* "Software"), to deal in the Software without restriction, including */
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/* without limitation the rights to use, copy, modify, merge, publish, */
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/* distribute, sublicense, and/or sell copies of the Software, and to */
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/* permit persons to whom the Software is furnished to do so, subject to */
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/* the following conditions: */
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/* */
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/* The above copyright notice and this permission notice shall be */
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/* included in all copies or substantial portions of the Software. */
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/* */
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/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
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/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
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/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
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/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
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/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
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/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
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/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
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/*************************************************************************/
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#include "math_funcs.h"
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#include "core/os/os.h"
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#include "float.h"
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#include "pcg.h"
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pcg32_random_t Math::default_pcg = {1, PCG_DEFAULT_INC_64};
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#define PHI 0x9e3779b9
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#if 0
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static uint32_t Q[4096];
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#endif
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// TODO: we should eventually expose pcg.inc too
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uint32_t Math::rand_from_seed(uint64_t *seed) {
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pcg32_random_t pcg = {*seed, PCG_DEFAULT_INC_64};
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uint32_t r = pcg32_random_r(&pcg);
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*seed = pcg.state;
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return r;
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}
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void Math::seed(uint64_t x) {
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default_pcg.state=x;
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}
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void Math::randomize() {
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OS::Time time = OS::get_singleton()->get_time();
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seed(OS::get_singleton()->get_ticks_usec()*(time.hour+1)*(time.min+1)*(time.sec+1)*rand()); // TODO: can be simplified.
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}
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uint32_t Math::rand() {
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return pcg32_random_r(&default_pcg);
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}
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double Math::randf() {
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return (double)rand() / (double)Math::RANDOM_MAX;
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}
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double Math::round(double p_val) {
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if (p_val>=0) {
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return ::floor(p_val+0.5);
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} else {
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p_val=-p_val;
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return -::floor(p_val+0.5);
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}
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}
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double Math::dectime(double p_value,double p_amount, double p_step) {
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float sgn = p_value < 0 ? -1.0 : 1.0;
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float val = absf(p_value);
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val-=p_amount*p_step;
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if (val<0.0)
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val=0.0;
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return val*sgn;
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}
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int Math::step_decimals(double p_step) {
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static const int maxn=9;
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static const double sd[maxn]={
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0.9999, // somehow compensate for floating point error
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0.09999,
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0.009999,
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0.0009999,
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0.00009999,
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0.000009999,
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0.0000009999,
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0.00000009999,
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0.000000009999
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};
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double as=absf(p_step);
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for(int i=0;i<maxn;i++) {
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if (as>=sd[i]) {
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return i;
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}
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}
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return maxn;
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}
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double Math::ease(double p_x, double p_c) {
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if (p_x<0)
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p_x=0;
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else if (p_x>1.0)
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p_x=1.0;
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if (p_c>0) {
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if (p_c<1.0) {
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return 1.0-Math::pow(1.0-p_x,1.0/p_c);
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} else {
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return Math::pow(p_x,p_c);
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}
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} else if (p_c<0) {
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//inout ease
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if (p_x<0.5) {
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return Math::pow(p_x*2.0,-p_c)*0.5;
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} else {
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return (1.0-Math::pow(1.0-(p_x-0.5)*2.0,-p_c))*0.5+0.5;
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}
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} else
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return 0; // no ease (raw)
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}
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double Math::stepify(double p_value,double p_step) {
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if (p_step!=0) {
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p_value=floor( p_value / p_step + 0.5 ) * p_step;
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}
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return p_value;
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}
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uint32_t Math::larger_prime(uint32_t p_val) {
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static const uint32_t primes[] = {
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5,
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13,
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23,
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47,
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97,
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193,
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389,
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769,
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1543,
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3079,
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6151,
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12289,
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24593,
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49157,
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98317,
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196613,
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393241,
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786433,
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1572869,
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3145739,
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6291469,
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12582917,
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25165843,
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50331653,
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100663319,
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201326611,
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402653189,
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805306457,
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1610612741,
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0,
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};
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int idx=0;
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while (true) {
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ERR_FAIL_COND_V(primes[idx]==0,0);
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if (primes[idx]>p_val)
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return primes[idx];
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idx++;
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}
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return 0;
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}
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double Math::random(double from, double to) {
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unsigned int r = Math::rand();
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double ret = (double)r/(double)RANDOM_MAX;
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return (ret)*(to-from) + from;
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}
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double Math::pow(double x, double y) {
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return ::pow(x,y);
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}
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double Math::log(double x) {
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return ::log(x);
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}
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double Math::exp(double x) {
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return ::exp(x);
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}
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