source/graphics/SmoothedValue.cpp

   1 /* Copyright (C) 2019 Wildfire Games.
   2 * This file is part of 0 A.D.
   3 *
   4 * 0 A.D. is free software: you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License as published by
   6 * the Free Software Foundation, either version 2 of the License, or
   7 * (at your option) any later version.
   8 *
   9 * 0 A.D. is distributed in the hope that it will be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
  16 */
  17
  18 #include "precompiled.h"
  19
  20 #include <cmath>
  21
  22 #include "graphics/SmoothedValue.h"
  23
  24 CSmoothedValue::CSmoothedValue(float value, float smoothness, float minDelta)
  25         : m_Target(value),
  26           m_Current(value),
  27           m_Smoothness(smoothness),
  28           m_MinDelta(minDelta)
  29 {
  30 }
  31
  32 float CSmoothedValue::Update(float time)
  33 {
  34         if (fabs(m_Target - m_Current) < m_MinDelta)
  35                 return 0.0f;
  36
  37         double p = pow(static_cast<double>(m_Smoothness), 10.0 * static_cast<double>(time));
  38         // (add the factor of 10 so that smoothnesses don't have to be tiny numbers)
  39
  40         double delta = (m_Target - m_Current) * (1.0 - p);
  41         m_Current += delta;
  42         return static_cast<float>(delta);
  43 }
  44
  45 void CSmoothedValue::Wrap(float min, float max)
  46 {
  47         double t = fmod(m_Target - min, static_cast<double>(max - min));
  48         if (t < 0)
  49                 t += max - min;
  50         t += min;
  51
  52         m_Current += t - m_Target;
  53         m_Target = t;
  54 }