void MergeSections(int a, int b)
{
int intervalLength = entries.Count / sortSegmentCount;
//'a' is known to be less than b, which means it cannot be the last section.
int aStart = intervalLength * a;
int aEnd = intervalLength * (a + 1);
int bStart = intervalLength * b;
int bEnd;
int length;
if (b == sortSegmentCount - 1)
{
bEnd = entries.Count;
length = intervalLength + entries.Count - bStart;
}
else
{
bEnd = intervalLength * (b + 1);
length = intervalLength * 2;
}
int aIndex = aStart, bIndex = bStart;
int i = 0;
while (i < length)
{
//Compute the location in the buffer array to put the minimum element.
int bufferIndex;
if (i >= intervalLength) //a length is intervalLength.
bufferIndex = bStart + i - intervalLength;
else
bufferIndex = aStart + i;
if (aIndex < aEnd && bIndex < bEnd)
{
//Compare the element at a to the one at b.
if (entries.Elements[aIndex].boundingBox.Min.X < entries.Elements[bIndex].boundingBox.Min.X)
{
//a was the minimum element. Put it into the buffer and increment the considered a index.
backbuffer.Elements[bufferIndex] = entries.Elements[aIndex++];
}
else
{
//b was the minimum element. Put it into the buffer and increment the considered b index.
backbuffer.Elements[bufferIndex] = entries.Elements[bIndex++];
}
}
else if (aIndex < aEnd)
{
//B is at the max, so just use a.
backbuffer.Elements[bufferIndex] = entries.Elements[aIndex++];
}
else
{
//A is at the max, so just use b.
backbuffer.Elements[bufferIndex] = entries.Elements[bIndex++];
}
i++;
}
}
}
