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/* Starshatter: The Open Source Project
Copyright (c) 2021-2022, Starshatter: The Open Source Project Contributors
Copyright (c) 2011-2012, Starshatter OpenSource Distribution Contributors
Copyright (c) 1997-2006, Destroyer Studios LLC.
AUTHOR: John DiCamillo
OVERVIEW
========
Utility functions for generating random numbers and locations.
*/
#include "MemDebug.h"
#include "Random.h"
// +----------------------------------------------------------------------+
void RandomInit()
{
srand(timeGetTime());
}
// +----------------------------------------------------------------------+
Point RandomDirection()
{
Point p = Point(rand() - 16384, rand() - 16384, 0);
p.Normalize();
return p;
}
// +----------------------------------------------------------------------+
Point RandomPoint()
{
Point p = Point(rand() - 16384, rand() - 16384, 0);
p.Normalize();
p *= 15e3 + rand()/3;
return p;
}
// +----------------------------------------------------------------------+
Vec3 RandomVector(double radius)
{
Vec3 v = Vec3(rand() - 16384, rand() - 16384, rand() - 16384);
v.Normalize();
if (radius > 0)
v *= (float) radius;
else
v *= (float) Random(radius/3, radius);
return v;
}
// +----------------------------------------------------------------------+
double Random(double min, double max)
{
double delta = max - min;
double r = delta * rand() / 32768.0;
return min + r;
}
// +----------------------------------------------------------------------+
int RandomIndex()
{
static int index = 0;
static int table[16] = { 0, 9, 4, 7, 14, 11, 2, 12, 1, 5, 13, 8, 6, 10, 3, 15 };
int r = 1 + ((rand() & 0x0700) >> 8);
index += r;
if (index > 1e7) index = 0;
return table[index % 16];
}
// +----------------------------------------------------------------------+
bool RandomChance(int wins, int tries)
{
double fraction = 256.0 * wins / tries;
double r = (rand() >> 4) & 0xFF;
return r < fraction;
}
// +----------------------------------------------------------------------+
int RandomSequence(int current, int range)
{
if (range > 1) {
int step = (int) Random(1, range-1);
return (current + step) % range;
}
return current;
}
// +----------------------------------------------------------------------+
int RandomShuffle(int count)
{
static int set_size = -1;
static BYTE set[256];
static int index = -1;
if (count < 0 || count > 250)
return 0;
if (set_size != count) {
set_size = count;
index = -1;
}
// need to reshuffle
if (index < 0 || index > set_size-1) {
// set up the deck
int tmp[256];
for (int i = 0; i < 256; i++)
tmp[i] = i;
// shuffle the cards
for (int i = 0; i < set_size; i++) {
int n = (int) Random(0, set_size);
int tries = set_size;
while (tmp[n] < 0 && tries--) {
n = (n+1) % set_size;
}
if (tmp[n] >= 0) {
set[i] = tmp[n];
tmp[n] = -1;
}
else {
set[i] = 0;
}
}
index = 0;
}
return set[index++];
}
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