/// <summary>
/// Determines the mtv along axis to move rect at pos1 to prevent intersection with poly at pos2
/// </summary>
/// <param name="rect">Rectangle</param>
/// <param name="poly">polygon</param>
/// <param name="pos1">Origin of rectangle</param>
/// <param name="pos2">Origin of polygon</param>
/// <param name="rot2">Rotation of the polygon in radians</param>
/// <param name="axis">Axis to check</param>
/// <returns>Number if rect intersects poly along axis, null otherwise</returns>
public static float?IntersectMTVAlongAxis(Rect2 rect, Polygon2 poly, Vector2 pos1, Vector2 pos2, Rotation2 rot2, Vector2 axis)
{
var proj1 = Rect2.ProjectAlongAxis(rect, pos1, axis);
var proj2 = Polygon2.ProjectAlongAxis(poly, pos2, rot2, axis);
return(AxisAlignedLine2.IntersectMTV(proj1, proj2));
}
/// <summary>
/// Determines if the specified polygon and rectangle where poly is at pos1 and rect is at pos2 intersect
/// along the specified axis.
/// </summary>
/// <param name="poly">polygon</param>
/// <param name="rect">Rectangle</param>
/// <param name="pos1">Origin of polygon</param>
/// <param name="pos2">Origin of rectangle</param>
/// <param name="rot1">Rotation of the polygon.</param>
/// <param name="strict">If overlap is required for intersection</param>
/// <param name="axis">Axis to check</param>
/// <returns>If poly at pos1 intersects rect at pos2 along axis</returns>
public static bool IntersectsAlongAxis(Polygon2 poly, Rect2 rect, Vector2 pos1, Vector2 pos2, Rotation2 rot1, bool strict, Vector2 axis)
{
var proj1 = Polygon2.ProjectAlongAxis(poly, pos1, rot1, axis);
var proj2 = Rect2.ProjectAlongAxis(rect, pos2, axis);
return(AxisAlignedLine2.Intersects(proj1, proj2, strict));
}
/// <summary>
/// Determines the minimum translation vector to be applied to the circle to
/// prevent overlap with the rectangle, when they are at their given positions.
/// </summary>
/// <param name="circle">The circle</param>
/// <param name="rect">The rectangle</param>
/// <param name="pos1">The top-left of the circles bounding box</param>
/// <param name="pos2">The rectangles origin</param>
/// <returns>MTV for circle at pos1 to prevent overlap with rect at pos2</returns>
public static Tuple <Vector2, float> IntersectMTV(Circle2 circle, Rect2 rect, Vector2 pos1, Vector2 pos2)
{
// Same as polygon rect, just converted to rects points
HashSet <Vector2> checkedAxis = new HashSet <Vector2>();
Vector2 bestAxis = Vector2.Zero;
float shortestOverlap = float.MaxValue;
Func <Vector2, bool> checkAxis = (axis) =>
{
var standard = Math2.MakeStandardNormal(axis);
if (!checkedAxis.Contains(standard))
{
checkedAxis.Add(standard);
var circleProj = Circle2.ProjectAlongAxis(circle, pos1, axis);
var rectProj = Rect2.ProjectAlongAxis(rect, pos2, axis);
var mtv = AxisAlignedLine2.IntersectMTV(circleProj, rectProj);
if (!mtv.HasValue)
{
return(false);
}
if (Math.Abs(mtv.Value) < Math.Abs(shortestOverlap))
{
bestAxis = axis;
shortestOverlap = mtv.Value;
}
}
return(true);
};
var circleCenter = new Vector2(pos1.X + circle.Radius, pos1.Y + circle.Radius);
int last = 4;
var lastVec = rect.UpperRight + pos2;
for (int curr = 0; curr < 4; curr++)
{
Vector2 currVec = Vector2.Zero;
switch (curr)
{
case 0:
currVec = rect.Min + pos2;
break;
case 1:
currVec = rect.LowerLeft + pos2;
break;
case 2:
currVec = rect.Max + pos2;
break;
case 3:
currVec = rect.UpperRight + pos2;
break;
}
// Test along circle center -> vector
if (!checkAxis(Vector2.Normalize(currVec - circleCenter)))
{
return(null);
}
// Test along line normal
if (!checkAxis(Vector2.Normalize(Math2.Perpendicular(currVec - lastVec))))
{
return(null);
}
last = curr;
lastVec = currVec;
}
return(Tuple.Create(bestAxis, shortestOverlap));
}
