public void checkInteraction(Rect otherRect)
{
//Is the other rect inside this rect? Are all four of its points contained?
if(ContainsPoint(otherRect.topLeft) && ContainsPoint(otherRect.topRight) && ContainsPoint(otherRect.botLeft) && ContainsPoint(otherRect.botRight))
{
containing = true;
otherRect.contained = true;
}
//Is the other rect intersecting this rect? Is at least one corner contained?
else if(ContainsPoint(otherRect.topLeft) || ContainsPoint(otherRect.topRight) || ContainsPoint(otherRect.botLeft) || ContainsPoint(otherRect.botRight))
{
intersecting = true;
otherRect.intersecting = true;
determineIntersections(otherRect);
}
//Are the two overlapping in a T shape, where no corners are contained but four intersections still occur?
else if(CheckForT(otherRect))
{
intersecting = true;
otherRect.intersecting = true;
intPoints[0].changePos(topLeft.X, otherRect.topLeft.Y);
intPoints[1].changePos(topRight.X, otherRect.topRight.Y);
intPoints[2].changePos(botLeft.X, otherRect.botLeft.Y);
intPoints[3].changePos(botRight.X, otherRect.botRight.Y);
}
//After all other checks, check each side for adjacency
CheckForAdj(otherRect);
}
bool CheckForT(Rect otherRect)
{
//If all the points of otherRect are below the top of this one, and above the bottom of this one,
//and all the points of this one are to the right of otherRect's left, and to the left of otherRect's right,
//the two are colliding in a T.
//We're checking for this:
/*
_____
_______|___|__
| | | |
| | | |
-------|---|--|
|___|
*/
bool otherBetweenTopAndBot;
bool thisBetweenLeftAndRight;
otherBetweenTopAndBot = (otherRect.topLeft.Y >= topLeft.Y && otherRect.botRight.Y >= topLeft.Y && otherRect.topLeft.Y <= botRight.Y && otherRect.botRight.Y <= botRight.Y);
thisBetweenLeftAndRight = (topLeft.X >= otherRect.topLeft.X && topRight.X >= otherRect.topLeft.X && topLeft.X <= otherRect.botRight.X && topRight.X <= otherRect.botRight.X);
return otherBetweenTopAndBot && thisBetweenLeftAndRight;
}
void determineIntersections(Rect otherRect)
{
//First, we check for the top left corner. Then, check adjacent corners, and determine intersections
//based on those adjacent corners.
if(ContainsPoint(otherRect.topLeft))
{
//These series of cases cover the first three of eight potential outcomes:
//the top left and top right corners are inside,
//and the top left and bottom left corners are inside,
//and only the top left corner is inside,
if (ContainsPoint(otherRect.topRight))
{
intPoints[0].changePos(otherRect.topLeft.X, botLeft.Y);
intPoints[1].changePos(otherRect.topRight.X, botLeft.Y);
}
else if(ContainsPoint(otherRect.botLeft))
{
intPoints[0].changePos(topRight.X, otherRect.topLeft.Y);
intPoints[1].changePos(topRight.X, otherRect.botLeft.Y);
}
else
{
intPoints[0].changePos(otherRect.topLeft.X, botRight.Y);
intPoints[1].changePos(botRight.X, otherRect.topLeft.Y);
}
}
//We do the same with the bottom right. This covers three more cases,
//The bottom right and bottom left corners are inside,
//the bottom right and top right corners are inside,
//and only the bottom right corner is inside.
else if(ContainsPoint(otherRect.botRight))
{
if(ContainsPoint(otherRect.botLeft))
{
intPoints[0].changePos(otherRect.botLeft.X, topLeft.Y);
intPoints[1].changePos(otherRect.botRight.X, topLeft.Y);
}
else if(ContainsPoint(otherRect.topRight))
{
intPoints[0].changePos(topLeft.X, otherRect.topRight.Y);
intPoints[1].changePos(topLeft.X, otherRect.botRight.Y);
}
else
{
intPoints[0].changePos(otherRect.botRight.X, topLeft.Y);
intPoints[1].changePos(topLeft.X, otherRect.botRight.Y);
}
}
//At this point, there are only two unaccounted for cases:
//Only the bottom left is inside, and only the top right is inside.
//First, we check the bottom left.
else if(ContainsPoint(otherRect.botLeft))
{
intPoints[0].changePos(otherRect.botLeft.X, topRight.Y);
intPoints[1].changePos(topRight.X, otherRect.botLeft.Y);
}
//If we have reached here, the intersecting point must be the top right.
else
{
intPoints[0].changePos(otherRect.topRight.X, botLeft.Y);
intPoints[1].changePos(botLeft.X, otherRect.topRight.Y);
}
}
void CheckForAdj(Rect otherRect)
{
//If the left is the same as or a subset of the other's right or left, color it yellow.
//Likewise, do the same for right, top and bottom.
//All sides are transparent until proven to be adjacent
for(int i = 0; i < 4; i++)
{
for(int j = 0; j < 4; j++)
{
//The top and bottom are even indices, the right and left are odd indices.
//Only check against the indices which have the same even or odd property.
if( (i % 2) == (j % 2) )
{
if(i % 2 == 0)
{
if (Math.Abs(lines[i].startPoint.Y - otherRect.lines[j].startPoint.Y) < float.Epsilon && lines[i].startPoint.X >= otherRect.lines[j].startPoint.X && lines[i].endPoint.X <= otherRect.lines[j].endPoint.X)
{
adjacent = true;
lines[i].adjacent = true;
}
}
else
{
//if(Math.Abs(topLeft.X - otherRect.topLeft.X) < float.Epsilon && topLeft.Y >= otherRect.topLeft.Y && botLeft.Y <= otherRect.botLeft.Y)
if (Math.Abs(lines[i].startPoint.X - otherRect.lines[j].startPoint.X) < float.Epsilon && lines[i].startPoint.Y >= otherRect.lines[j].startPoint.Y && lines[i].endPoint.Y <= otherRect.lines[j].endPoint.Y)
{
adjacent = true;
lines[i].adjacent = true;
}
}
}
}
}
}