minetest/src/lighting.h

/*
Minetest
Copyright (C) 2021 x2048, Dmitry Kostenko <codeforsmile@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


/**
 * Parameters for automatic exposure compensation
 *
 * Automatic exposure compensation uses the following equation:
 *
 * wanted_exposure = 2^exposure_correction / clamp(observed_luminance, 2^luminance_min, 2^luminance_max)
 *
 */
struct AutoExposure
{
    /// @brief Minimum boundary for computed luminance
    float luminance_min;
    /// @brief Maximum boundary for computed luminance
    float luminance_max;
    /// @brief Luminance bias. Higher values make the scene darker, can be negative.
    float exposure_correction;
    /// @brief Speed of transition from dark to bright scenes
    float speed_dark_bright;
    /// @brief Speed of transition from bright to dark scenes
    float speed_bright_dark;
    /// @brief Power value for center-weighted metering. Value of 1.0 measures entire screen uniformly
    float center_weight_power;

    AutoExposure();
};

/** Describes ambient light settings for a player
 */
struct Lighting
{
    AutoExposure exposure;
    float shadow_intensity {0.0f};
    float saturation {1.0f};
};