public static int decompose_overlapping(RECT A, RECT B, RECT [] ra)
{
int overlaps = 0;
RECT C;
RECT i;
if (A.overlaps_interior(B))
{
if (B.y0 < A.y0)
{
//0
C = new RECT(B.x0, B.y0, B.w, A.y0 - B.y0);
i = C.intersection(B);
if (!is_sliver(i))
{
ra[overlaps] = i;
RECTTOOLS.CHECK_NO_INTERIOR_OVERLAP(C, A);
overlaps++;
}
}
if (B.x1 > A.x1)
{
//1
C = RECT.FromPoints(A.x1, A.y0, B.x1, A.y1);
i = C.intersection(B);
if (!is_sliver(i))
{
RECTTOOLS.CHECK_NO_INTERIOR_OVERLAP(C, A);
ra[overlaps] = i;
overlaps++;
}
}
if (B.x0 < A.x0)
{
//2
C = RECT.FromPoints(B.x0, A.y0, A.x0, A.y1);
i = C.intersection(B);
if (!is_sliver(i))
{
RECTTOOLS.CHECK_NO_INTERIOR_OVERLAP(C, A);
ra[overlaps] = i;
overlaps++;
}
}
if (B.y1 > A.y1)
{
//3
C = new RECT(B.x0, A.y1, B.w, B.y1 - A.y1);
i = C.intersection(B);
if (!is_sliver(i))
{
ra[overlaps] = i;
overlaps++;
}
}
}
return(overlaps);
}
public static void CHECK_NO_INTERIOR_OVERLAP(RECT A, RECT B)
{
if (A.overlaps_interior(B))
{
RECT i = A.intersection(B);
if ((i.w >= 1.0) && (i.h >= 1.0))
{
throw new Exception("should not overlap");
}
}
}
public void TestIntersection()
{
RECT rA = new RECT(10,10,10,10);
RECT rB = new RECT(0,0,30,30);
RECT rC = new RECT(15,15,20,20);
RECT rD = new RECT(0,0,15,15);
RECT rI;
rI = rA.intersection( rB );
Assertion.AssertEquals( rI, rA );
rI = rA.intersection( rC );
Assertion.AssertEquals( rI, new RECT( 15,15,5,5 ) );
rI = rA.intersection( rD );
Assertion.AssertEquals( rI, new RECT( 10,10,5,5 ) );
}