//worst case O(n)
public Hull combine(Hull left, Hull right)
{
//extract lists from hulls
List <PointF> l = left.getList();
List <PointF> r = right.getList();
//set booleans, they come in handy
bool bothDone = false;
bool rightDone = false;
bool leftDone = false;
//those 4 ints abreviate topleftindex,toprightindex,bottomleftindex,and bottomrightindex
int tli = left.getRightIndex();
int tri = 0;
int bli = left.getRightIndex();
int bri = 0;
//find top edge, repeat this loop until no change in left or right index
while (!bothDone)
{
bothDone = true;
rightDone = false;
leftDone = false;
//move right index "up" until no advantage in slope change
while (!rightDone)
{
int newIndex;
if (tri == 0)
{
newIndex = r.Count() - 1;
}
else
{
newIndex = tri - 1;
}
if (slope(l[tli], r[tri]) > slope(l[tli], r[newIndex]))
{
tri = newIndex;
bothDone = false;
}
else
{
rightDone = true;
}
}
//move left index "up" until no advantage in slope change
while (!leftDone)
{
int newIndex;
if (tli == (l.Count() - 1))
{
newIndex = 0;
}
else
{
newIndex = tli + 1;
}
if (slope(l[tli], r[tri]) < slope(l[newIndex], r[tri]))
{
tli = newIndex;
bothDone = false;
}
else
{
leftDone = true;
}
}
}
bothDone = false;
//find bottom edge, repeat this loop until no change in left or right index
while (!bothDone)
{
bothDone = true;
rightDone = false;
leftDone = false;
//move right index "down" until no advantage in slope change
while (!rightDone)
{
if (bri == (r.Count() - 1))
{
rightDone = true;
}
else
{
if (slope(l[bli], r[bri]) < slope(l[bli], r[bri + 1]))
{
bri++;
bothDone = false;
}
else
{
rightDone = true;
}
}
}
//move left index "down" until no advantage in slope change
while (!leftDone)
{
if (bli == 0)
{
leftDone = true;
}
else
{
if (slope(l[bli], r[bri]) > slope(l[bli - 1], r[bri]))
{
bli--;
bothDone = false;
}
else
{
leftDone = true;
}
}
}
}
//pass in the indeces we found
return(getNewHull(bli, bri, tri, tli, right.getRightIndex(), l, r));
}
public Hull merge(Hull left, Hull right)
{
int rightMost = left.getRightMostIndex();
int leftMost = right.getLeftMostIndex();
int currentLeftIndex = rightMost;
int currentRightIndex = leftMost;
int upperLeft = -1;
int upperRight = -1;
int lowerLeft = -1;
int lowerRight = -1;
bool leftIndexChanged = false;
bool rightIndexChanged = false;
//iterate through at least once
bool firstRight = true;
bool firstLeft = true;
//get upper common tangent
while (leftIndexChanged || rightIndexChanged || firstLeft || firstRight)
{
if (firstRight || leftIndexChanged)
{
firstRight = false;
upperRight = getRightUpper(left, right, currentLeftIndex, currentRightIndex);
if (upperRight == currentRightIndex)
{
leftIndexChanged = false;
rightIndexChanged = false;
}
else
{
rightIndexChanged = true;
currentRightIndex = upperRight;
}
}
if (firstLeft || rightIndexChanged)
{
firstLeft = false;
upperLeft = getLeftUpper(left, right, currentLeftIndex, currentRightIndex);
if (upperLeft == currentLeftIndex)
{
leftIndexChanged = false;
rightIndexChanged = false;
}
else
{
leftIndexChanged = true;
currentLeftIndex = upperLeft;
}
}
}
//get lower common tangentt
currentLeftIndex = rightMost;
currentRightIndex = leftMost;
leftIndexChanged = false;
rightIndexChanged = false;
//iterate through at least once
firstRight = true;
firstLeft = true;
while (leftIndexChanged || rightIndexChanged || firstLeft || firstRight)
{
if (firstLeft || rightIndexChanged)
{
firstLeft = false;
lowerLeft = getLeftLower(left, right, currentLeftIndex, currentRightIndex);
if (lowerLeft == currentLeftIndex)
{
leftIndexChanged = false;
rightIndexChanged = false;
}
else
{
leftIndexChanged = true;
currentLeftIndex = lowerLeft;
}
}
if (firstRight || leftIndexChanged)
{
firstRight = false;
lowerRight = getRightLower(left, right, currentLeftIndex, currentRightIndex);
if (lowerRight == currentRightIndex)
{
leftIndexChanged = false;
rightIndexChanged = false;
}
else
{
rightIndexChanged = true;
currentRightIndex = lowerRight;
}
}
}
//join points
List <PointF> resultPoints = new List <PointF>();
//add up to (and including) upperLeft
for (int i = 0; i <= upperLeft; i++)
{
resultPoints.Add(left.getPoints()[i]);
}
//add up to lowerRight
for (int i = upperRight; i != lowerRight; i = right.getNextIndex(i))
{
resultPoints.Add(right.getPoints()[i]);
}
//add lowerRight
resultPoints.Add(right.getPoints()[lowerRight]);
//add from lowerLeft to beginning
for (int i = lowerLeft; i != 0; i = left.getNextIndex(i))
{
resultPoints.Add(left.getPoints()[i]);
}
return(new Hull(resultPoints));
}
