/// <summary>
/// Returns true if a rectangle centered at the given point, at the
/// given angle and dimensions, will fit in the polygon.
/// </summary>
private bool WillRectangleFit(Edge[] edges, Vector2 center, float angleRad, float width, float height)
{
float halfWidth = width / 2;
float halfHeight = height / 2;
var topLeft = new Vector2(center.x - halfWidth, center.y + halfHeight);
var topRight = new Vector2(center.x + halfWidth, center.y + halfHeight);
var bottomLeft = new Vector2(center.x - halfWidth, center.y - halfHeight);
var bottomRight = new Vector2(center.x + halfWidth, center.y - halfHeight);
topLeft = RotatePoint(center, angleRad, topLeft);
topRight = RotatePoint(center, angleRad, topRight);
bottomLeft = RotatePoint(center, angleRad, bottomLeft);
bottomRight = RotatePoint(center, angleRad, bottomRight);
var top = new Edge(topLeft, topRight);
var right = new Edge(topRight, bottomRight);
var bottom = new Edge(bottomLeft, bottomRight);
var left = new Edge(topLeft, bottomLeft);
// If any edges of the polygon intersect with any of our edges, it won't fit
foreach (var edge in edges)
{
if (EdgeHelpers.IsValidPoint(EdgeHelpers.GetIntersection(edge, top)) || EdgeHelpers.IsValidPoint(EdgeHelpers.GetIntersection(edge, right)) ||
EdgeHelpers.IsValidPoint(EdgeHelpers.GetIntersection(edge, bottom)) || EdgeHelpers.IsValidPoint(EdgeHelpers.GetIntersection(edge, left)))
{
return(false);
}
}
return(true);
}
/// <summary>
/// Given a point inside of the boundary, finds the points on the
/// boundary directly above, below, left and right of the point,
/// with respect to the given angle.
/// </summary>
private bool FindSurroundingCollisionPoints(
Edge[] edges,
Vector2 point, float angleRad, out Vector2 topCollisionPoint,
out Vector2 bottomCollisionPoint, out Vector2 leftCollisionPoint,
out Vector2 rightCollisionPoint)
{
topCollisionPoint = EdgeHelpers.InvalidPoint;
bottomCollisionPoint = EdgeHelpers.InvalidPoint;
leftCollisionPoint = EdgeHelpers.InvalidPoint;
rightCollisionPoint = EdgeHelpers.InvalidPoint;
bool isInside = EdgeHelpers.IsInside(edges, point);
if (!isInside)
{
return(false);
}
// Find the top and bottom collision points by creating a large line segment that goes through the point to MAX and MIN values on Y
var topEndpoint = new Vector2(point.x, largeValue);
var bottomEndpoint = new Vector2(point.x, smallValue);
topEndpoint = RotatePoint(point, angleRad, topEndpoint);
bottomEndpoint = RotatePoint(point, angleRad, bottomEndpoint);
var verticalLine = new Edge(topEndpoint, bottomEndpoint);
// Find the left and right collision points by creating a large line segment that goes through the point to MAX and Min values on X
var rightEndpoint = new Vector2(largeValue, point.y);
var leftEndpoint = new Vector2(smallValue, point.y);
rightEndpoint = RotatePoint(point, angleRad, rightEndpoint);
leftEndpoint = RotatePoint(point, angleRad, leftEndpoint);
var horizontalLine = new Edge(rightEndpoint, leftEndpoint);
// Loop the edges and find the nearest intersection point
foreach (var edge in edges)
{
Vector2 verticalIntersection = EdgeHelpers.GetIntersection(edge, verticalLine);
if (EdgeHelpers.IsValidPoint(verticalIntersection))
{
// Is this intersection above or below the point?
bool isAbove = RotatePoint(point, -angleRad, verticalIntersection).y > point.y;
if (isAbove)
{
// If this collision point is closer than the previous one
if (!EdgeHelpers.IsValidPoint(topCollisionPoint) ||
Vector2.SqrMagnitude(point - verticalIntersection) < Vector2.SqrMagnitude(point - topCollisionPoint))
{
topCollisionPoint = verticalIntersection;
}
}
else
{
if (!EdgeHelpers.IsValidPoint(bottomCollisionPoint) ||
Vector2.SqrMagnitude(point - verticalIntersection) < Vector2.SqrMagnitude(point - bottomCollisionPoint))
{
bottomCollisionPoint = verticalIntersection;
}
}
} // If vertical intersection found
Vector2 horizontalIntersection = EdgeHelpers.GetIntersection(edge, horizontalLine);
if (EdgeHelpers.IsValidPoint(horizontalIntersection))
{
// Is this intersection left or right of the point?
bool isLeft = RotatePoint(point, -angleRad, horizontalIntersection).x < point.x;
if (isLeft)
{
// Is it closer than the previous intersection?
if (!EdgeHelpers.IsValidPoint(leftCollisionPoint) ||
Vector2.SqrMagnitude(point - horizontalIntersection) < Vector2.SqrMagnitude(point - leftCollisionPoint))
{
leftCollisionPoint = horizontalIntersection;
}
}
else
{
// Is it closer than the previous intersection?
if (!EdgeHelpers.IsValidPoint(rightCollisionPoint) ||
Vector2.SqrMagnitude(point - horizontalIntersection) < Vector2.SqrMagnitude(point - rightCollisionPoint))
{
rightCollisionPoint = horizontalIntersection;
}
}
}
}
// Assert that any point inside should have intersection points on all sides with the polygon
if (!EdgeHelpers.IsValidPoint(topCollisionPoint) || !EdgeHelpers.IsValidPoint(bottomCollisionPoint) ||
!EdgeHelpers.IsValidPoint(leftCollisionPoint) || !EdgeHelpers.IsValidPoint(rightCollisionPoint))
{
return(false);
}
return(true);
}