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https://github.com/godotengine/godot
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80 lines
3.4 KiB
C++
80 lines
3.4 KiB
C++
/**************************************************************************/
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/* random_pcg.cpp */
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/**************************************************************************/
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/* This file is part of: */
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/* GODOT ENGINE */
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/* https://godotengine.org */
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/**************************************************************************/
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/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
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/* Copyright (c) 2007-2014 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 "random_pcg.h"
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#include "core/os/os.h"
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#include "core/templates/vector.h"
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RandomPCG::RandomPCG(uint64_t p_seed, uint64_t p_inc) :
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pcg(),
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current_inc(p_inc) {
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seed(p_seed);
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}
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void RandomPCG::randomize() {
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seed(((uint64_t)OS::get_singleton()->get_unix_time() + OS::get_singleton()->get_ticks_usec()) * pcg.state + PCG_DEFAULT_INC_64);
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}
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int64_t RandomPCG::rand_weighted(const Vector<float> &p_weights) {
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ERR_FAIL_COND_V_MSG(p_weights.is_empty(), -1, "Weights array is empty.");
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int64_t weights_size = p_weights.size();
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const float *weights = p_weights.ptr();
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float weights_sum = 0.0;
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for (int64_t i = 0; i < weights_size; ++i) {
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weights_sum += weights[i];
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}
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float remaining_distance = randf() * weights_sum;
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for (int64_t i = 0; i < weights_size; ++i) {
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remaining_distance -= weights[i];
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if (remaining_distance < 0) {
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return i;
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}
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}
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return -1;
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}
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double RandomPCG::random(double p_from, double p_to) {
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return randd() * (p_to - p_from) + p_from;
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}
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float RandomPCG::random(float p_from, float p_to) {
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return randf() * (p_to - p_from) + p_from;
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}
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int RandomPCG::random(int p_from, int p_to) {
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if (p_from == p_to) {
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return p_from;
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}
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return rand(abs(p_from - p_to) + 1) + MIN(p_from, p_to);
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}
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