samples/game_controller/common/util.hpp

/*
 * Copyright 2021 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#pragma once

#include <cmath>
#include <ctime>

// Clean up a resource (delete and set to null).
template <typename T>
void CleanUp(T **pptr) {
  if (*pptr) {
    delete *pptr;
    *pptr = nullptr;
  }
}

int Random(int uboundExclusive);

int Random(int lbound, int uboundExclusive);

template <typename T>
T Max(T a, T b) {
  return a > b ? a : b;
}

template <typename T>
T Min(T a, T b) {
  return a < b ? a : b;
}

template <typename T>
T Clamp(T v, T min, T max) {
  return (v < min) ? min : (v > max) ? max : v;
}

// Linear interpolation. If x < x1, returns y1. If x > x2, returns y2. If x1 <=
// x <= x2, then let f() be a linear function such that f(x1) = y1 and f(x2) =
// y2. Returns f(x).
template <typename T>
T Interpolate(T x1, T y1, T x2, T y2, T x) {
  if (x2 < x1) return Interpolate(x2, y2, x1, y1, x);
  return (x < x1)   ? y1
         : (x > x2) ? y2
                    : y1 + ((x - x1) / (x2 - x1)) * (y2 - y1);
}

// If abs(orig - target) <= amount, returns target. Otherwise, returns
// either orig + amount or orig - amount, whichever one is closer to the target.
// Intuitively, this means we are at x=orig and are aiming at x=target, and can
// move up to <amount> units. For example, if orig is 50 and the target is 100,
// then moving it by 10 will yield 60. If the target were 0, it would yield
// 40. Now, if the target is within reach of the delta, the target is returned.
// So if we're at 50, the target is 60 and the delta amount is 20, this returns
// 60.
template <typename T>
T Approach(T orig, T target, T amount) {
  float absDiff = orig - target;
  if (absDiff < static_cast<T>(0)) absDiff = -absDiff;
  if (absDiff < amount) {
    return target;
  } else if (target > orig) {
    return orig + amount;
  } else {
    return orig - amount;
  }
}

template <typename T>
T Abs(T f) {
  return f > static_cast<T>(0) ? f : -f;
}

// Returns current wall clock time (seconds elapsed since an arbitrary fixed
// point in the past).
float Clock();

float SineWave(float min, float max, float period, float phase);

bool BlinkFunc(float period);

/* A simple chronometer that computes elapsed time. */
class DeltaClock {
 private:
  float mLastTick;
  float mMaxDelta;
  bool mHasMax;

 public:
  DeltaClock() {
    mLastTick = Clock();
    mHasMax = false;
  }

  DeltaClock(float maxDelta) {
    mLastTick = Clock();
    mMaxDelta = maxDelta;
    mHasMax = true;
  }

  float ReadDelta() {
    float d = Clamp(Clock() - mLastTick, 0.0f, mMaxDelta);
    mLastTick = Clock();
    return d;
  }

  void SetMaxDelta(float m) { mMaxDelta = m; }

  void Reset() { mLastTick = Clock(); }
};