daynightratio.h

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/*
Minetest
Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
 
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
 
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Lesser General Public License for more details.
 
You should have received a copy of the GNU Lesser General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
 
#pragma once
 
inline u32 time_to_daynight_ratio(float time_of_day, bool smooth)
{
    float t = time_of_day;
    if (t < 0.0f)
        t += ((int)(-t) / 24000) * 24000.0f;
    if (t >= 24000.0f)
        t -= ((int)(t) / 24000) * 24000.0f;
    if (t > 12000.0f)
        t = 24000.0f - t;
 
    const float values[9][2] = {
        {4250.0f + 125.0f, 175.0f},
        {4500.0f + 125.0f, 175.0f},
        {4750.0f + 125.0f, 250.0f},
        {5000.0f + 125.0f, 350.0f},
        {5250.0f + 125.0f, 500.0f},
        {5500.0f + 125.0f, 675.0f},
        {5750.0f + 125.0f, 875.0f},
        {6000.0f + 125.0f, 1000.0f},
        {6250.0f + 125.0f, 1000.0f},
    };
 
    if (!smooth) {
        float lastt = values[0][0];
        for (u32 i = 1; i < 9; i++) {
            float t0 = values[i][0];
            float switch_t = (t0 + lastt) / 2.0f;
            lastt = t0;
            if (switch_t <= t)
                continue;
 
            return values[i][1];
        }
        return 1000;
    }
 
    if (t <= 4625.0f) // 4500 + 125
        return values[0][1];
    else if (t >= 6125.0f) // 6000 + 125
        return 1000;
 
    for (u32 i = 0; i < 9; i++) {
        if (values[i][0] <= t)
            continue;
 
        float td0 = values[i][0] - values[i - 1][0];
        float f = (t - values[i - 1][0]) / td0;
        return f * values[i][1] + (1.0f - f) * values[i - 1][1];
    }
    return 1000;
}