Method SolveIntegralOfInverse

libraries/lib-mixer/Envelope.cpp:1350–1439

}

double Envelope::SolveIntegralOfInverse( double t0, double area ) const
{
   if(area == 0.0)
      return t0;

   const auto count = mEnv.size();
   if(count == 0) // 'empty' envelope
      return t0 + area * mDefaultValue;

   // Correct for offset!
   t0 -= mOffset;
   return mOffset + [&] {
      // Now we can safely assume t0 is relative time!
      double lastT, lastVal;
      int i; // this is the next point to check
      if(t0 < mEnv[0].GetT()) // t0 preceding the first point
      {
         if (area < 0) {
            return t0 + area * mEnv[0].GetVal();
         }
         else {
            i = 1;
            lastT = mEnv[0].GetT();
            lastVal = mEnv[0].GetVal();
            double added = (lastT - t0) / lastVal;
            if(added >= area)
               return t0 + area * mEnv[0].GetVal();
            area -= added;
         }
      }
      else if(t0 >= mEnv[count - 1].GetT()) // t0 at or following the last point
      {
         if (area < 0) {
            i = (int)count - 2;
            lastT = mEnv[count - 1].GetT();
            lastVal = mEnv[count - 1].GetVal();
            double added = (lastT - t0) / lastVal; // negative
            if(added <= area)
               return t0 + area * mEnv[count - 1].GetVal();
            area -= added;
         }
         else {
            return t0 + area * mEnv[count - 1].GetVal();
         }
      }
      else // t0 enclosed by points
      {
         // Skip any points that come before t0 using binary search
         int lo, hi;
         BinarySearchForTime(lo, hi, t0);
         lastVal = InterpolatePoints(mEnv[lo].GetVal(), mEnv[hi].GetVal(), (t0 - mEnv[lo].GetT()) / (mEnv[hi].GetT() - mEnv[lo].GetT()), mDB);
         lastT = t0;
         if (area < 0)
            i = lo;
         else
            i = hi; // the point immediately after t0.
      }