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#include "Random.h"
namespace SyntopiaCore {
namespace Math {
namespace {
struct SortPair {
SortPair() {};
SortPair(int index, double sortValue) : index(index), sortValue(sortValue) {};
int index;
double sortValue;
bool operator< (const SortPair& rhs) const { return sortValue < rhs.sortValue; }
};
}
QVector<int> RandomNumberGenerator::getRandomIndices(int count) {
QVector<SortPair> sp(count);
for (int i = 0; i < count; i++) sp[i] = SortPair(i, getDouble());
qSort(sp);
QVector<int> out(count);
for (int i = 0; i < count; i++) out[i] = sp[i].index;
return out;
}
Vector3f RandomNumberGenerator::getUniform2D() {
Vector3f v;
do {
v = Vector3f(getDouble(-1,1),getDouble(-1,1),0);
} while (v.sqrLength()>1.0);
return v;
}
Vector3f RandomNumberGenerator::getUniform3D() {
Vector3f v;
do {
v = Vector3f(getDouble(-1,1),getDouble(-1,1),getDouble(-1,1));
} while (v.sqrLength()>1.0);
return v;
}
namespace {
const int UniformTableSize = 10000; // size of precalculated tables.
}
// Uses precalculated tables.
// Initialized on first use (so init before using in multithreaded code)
Vector3f RandomNumberGenerator::getUniform2DFromTable() {
static QVector<Vector3f> uniform2D;
if (uniform2D.count() == 0) {
for (int i = 0; i < UniformTableSize; i++) uniform2D.append(getUniform2D());
}
uniformCounter2D++;
if (uniformCounter2D>=uniform2D.count()) uniformCounter2D = 0;
return uniform2D[uniformCounter2D];
}
Vector3f RandomNumberGenerator::getUniform3DFromTable() {
static QVector<Vector3f> uniform3D;
if (uniform3D.count() == 0) {
for (int i = 0; i < UniformTableSize; i++) uniform3D.append(getUniform3D());
}
uniformCounter3D++;
if (uniformCounter3D>=uniform3D.count()) uniformCounter3D = 0;
return uniform3D[uniformCounter3D];
}
void RandomNumberGenerator::randomizeUniformCounter(){
uniformCounter2D = getInt(UniformTableSize);
uniformCounter3D = getInt(UniformTableSize);
}
}
}
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