/// <summary>
/// Finds the closets point on the polygon to the specified point.
/// </summary>
/// <param name="point">The point to find the closest point to.</param>
/// <param name="vertices">The vertices describing the polygon.</param>
/// <param name="numVertices">The number of actual vertices in the vertices array.</param>
/// <returns>The point on the polygon that is closest to the specified point.</returns>
public static Vector2 FindClosestPointOnPolygon(Vector2 point, Vector2[] vertices, int numVertices)
{
// Find the closest point
Vector2 closestPoint = ShapeUtility.CalculateClosestPointOnEdge(point, vertices[0], vertices[1]);
float closestDistance = (closestPoint - point).LengthSquared();
for (int i = 1; i < numVertices; i++)
{
Vector2 closestPointOfEdge =
(i == numVertices - 1 ?
ShapeUtility.CalculateClosestPointOnEdge(point, vertices[i], vertices[0]) :
ShapeUtility.CalculateClosestPointOnEdge(point, vertices[i], vertices[i + 1]));
float currentDistance = (closestPointOfEdge - point).LengthSquared();
if (currentDistance < closestDistance)
{
closestPoint = closestPointOfEdge;
closestDistance = currentDistance;
}
}
return(closestPoint);
}
/// <summary>
/// Checks for intersection between a polygon and a circle.
/// </summary>
/// <param name="polygon">The circle.</param>
/// <param name="circle">The polygon.</param>
/// <returns>True if the two shapes intersect. False othwerise.</returns>
public static bool Intersects(IPolygon2D polygon, ICircle2D circle)
{
// See if the closest point of each edge to the circle's center is inside the center
Vector2 circleCenter = circle.Center;
for (int i = 0; i < polygon.NumSides; i++)
{
Vector2 closestPointOfEdge =
(i == polygon.NumSides - 1 ?
ShapeUtility.CalculateClosestPointOnEdge(circleCenter, polygon.Vertices[i], polygon.Vertices[0]) :
ShapeUtility.CalculateClosestPointOnEdge(circleCenter, polygon.Vertices[i], polygon.Vertices[i + 1]));
if (circle.Contains(closestPointOfEdge))
{
return(true);
}
}
// See if this polygon contains the other circle
if (polygon.Contains(circle.Center))
{
return(true);
}
return(false);
}
