|
public static Join ( |
||
| a | first joined rectangle /// | |
| b | second joined rectangle /// | |
| Результат | ||
/// <summary>
/// Non destructive join of two rectangles.
/// </summary>
/// <param name="a">first joined rectangle
/// </param>
/// <param name="b">second joined rectangle
/// </param>
/// <returns>rectangle containing cover of these two rectangles
/// </returns>
public static RectangleR2 Join(RectangleR2 a, RectangleR2 b)
{
RectangleR2 r = new RectangleR2(a);
r.Join(b);
return(r);
}
internal RectangleR2 cover()
{
RectangleR2 r = new RectangleR2(b[0]);
for (int i = 1; i < n; i++)
{
r.Join(b[i]);
}
return r;
}
RtreeR2Page splitPage(IDatabase db, RectangleR2 r, IPersistent obj)
{
int i, j, seed0 = 0, seed1 = 0;
double[] rectArea = new double[card + 1];
double waste;
double worstWaste = Double.MinValue;
//
// As the seeds for the two groups, find two rectangles which waste
// the most area if covered by a single rectangle.
//
rectArea[0] = r.Area();
for (i = 0; i < card; i++)
{
rectArea[i + 1] = b[i].Area();
}
RectangleR2 bp = r;
for (i = 0; i < card; i++)
{
for (j = i + 1; j <= card; j++)
{
waste = RectangleR2.JoinArea(bp, b[j - 1]) - rectArea[i] - rectArea[j];
if (waste > worstWaste)
{
worstWaste = waste;
seed0 = i;
seed1 = j;
}
}
bp = b[i];
}
byte[] taken = new byte[card];
RectangleR2 group0, group1;
double groupArea0, groupArea1;
int groupCard0, groupCard1;
RtreeR2Page pg;
taken[seed1 - 1] = 2;
group1 = new RectangleR2(b[seed1 - 1]);
if (seed0 == 0)
{
group0 = new RectangleR2(r);
pg = new RtreeR2Page(db, obj, r);
}
else
{
group0 = new RectangleR2(b[seed0 - 1]);
pg = new RtreeR2Page(db, branch.GetRaw(seed0 - 1), group0);
setBranch(seed0 - 1, r, obj);
}
groupCard0 = groupCard1 = 1;
groupArea0 = rectArea[seed0];
groupArea1 = rectArea[seed1];
//
// Split remaining rectangles between two groups.
// The one chosen is the one with the greatest difference in area
// expansion depending on which group - the rect most strongly
// attracted to one group and repelled from the other.
//
while (groupCard0 + groupCard1 < card + 1
&& groupCard0 < card + 1 - minFill
&& groupCard1 < card + 1 - minFill)
{
int betterGroup = -1, chosen = -1;
double biggestDiff = -1;
for (i = 0; i < card; i++)
{
if (taken[i] == 0)
{
double diff = (RectangleR2.JoinArea(group0, b[i]) - groupArea0)
- (RectangleR2.JoinArea(group1, b[i]) - groupArea1);
if (diff > biggestDiff || -diff > biggestDiff)
{
chosen = i;
if (diff < 0)
{
betterGroup = 0;
biggestDiff = -diff;
}
else
{
betterGroup = 1;
biggestDiff = diff;
}
}
}
}
Debug.Assert(chosen >= 0);
if (betterGroup == 0)
{
group0.Join(b[chosen]);
groupArea0 = group0.Area();
taken[chosen] = 1;
pg.setBranch(groupCard0++, b[chosen], branch.GetRaw(chosen));
}
else
{
groupCard1 += 1;
group1.Join(b[chosen]);
groupArea1 = group1.Area();
taken[chosen] = 2;
}
}
//
// If one group gets too full, then remaining rectangle are
// split between two groups in such way to balance cards of two groups.
//
if (groupCard0 + groupCard1 < card + 1)
{
for (i = 0; i < card; i++)
{
if (taken[i] == 0)
{
if (groupCard0 >= groupCard1)
{
taken[i] = 2;
groupCard1 += 1;
}
else
{
taken[i] = 1;
pg.setBranch(groupCard0++, b[i], branch.GetRaw(i));
}
}
}
}
pg.n = groupCard0;
n = groupCard1;
for (i = 0, j = 0; i < groupCard1; j++)
{
if (taken[j] == 2)
{
setBranch(i++, b[j], branch.GetRaw(j));
}
}
return pg;
}
/// <summary>
/// Non destructive join of two rectangles.
/// </summary>
/// <param name="a">first joined rectangle
/// </param>
/// <param name="b">second joined rectangle
/// </param>
/// <returns>rectangle containing cover of these two rectangles
/// </returns>
public static RectangleR2 Join(RectangleR2 a, RectangleR2 b)
{
RectangleR2 r = new RectangleR2(a);
r.Join(b);
return r;
}