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/****************************************************************************
**
** Copyright (C) 2009-2011 NVIDIA Corporation.
** Copyright (C) 2017 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of Qt 3D Studio.
**
** $QT_BEGIN_LICENSE:GPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 or (at your option) any later version
** approved by the KDE Free Qt Foundation. The licenses are as published by
** the Free Software Foundation and appearing in the file LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "nv_math.h"
static const double a = 16807.0;
static const double m = 2147483647.0;
static double nextSeed(double seed)
{
double t = a * seed;
return t - m * (double)((int)(t / m));
}
GLfloat NvRandf()
{
static double seed = 1.0;
seed = nextSeed(seed);
return (GLfloat)(seed * (1 / m));
}
GLfloat NvClockDiffInSecs(long long int newTime, long long int oldTime)
{
// kdGetTimeUST is never supposed to decrease (i.e. that
// means it can't wrap, either. IIRC, it will wrap in
// 593 years). So we ignore that option...
// Used for frame-to-frame diffs, this will fit in 32b
// as long as the times are < ~4.3s apart
long long int diffTime = newTime - oldTime;
// Need to find a better way to do this.
// However, I believe we will be uSec precise (not run
// out of mantissa bits for uSecs) as long as the diff
// is < ~16s (1e-6 * (2^24))
return ((GLfloat)diffTime) / 1.0e9f;
}
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