///Returns whether a line segment intersects a polygon (given a list of vertices)
public static bool LineSegIntersectsPoly(LineSeg lns, List <Vector2> verts)
{
//Check to see if either end of the segment is in the polygon
if (PointInPoly(lns.CenterA, verts) || PointInPoly(lns.CenterB, verts))
{
return(true);
}
int j = verts.Count - 1;
LineSeg lnsCheck = new LineSeg();
//checks every line segment in the polygon until an intersection is found
for (int i = 0; i < verts.Count; i++)
{
lnsCheck.SetA(verts[i]);
lnsCheck.SetB(verts[j]);
if (LineSegIntersectsLineSeg(lns, lnsCheck))
{
return(true);
}
j = i;
}
return(false);
}
/* Poly methods */
#region
///Returns whether a polygon intersects another polygon (given a list of vertices)
public static bool PolyIntersectsPoly(List <Vector2> verts1, List <Vector2> verts2)
{
//check to see if any vertices exist inside either polygon (more efficient and catches most cases)
for (int i = 0; i < verts1.Count; i++)
{
Vector2 vert = verts1[i];
if (PointInPoly(vert, verts2))
{
return(true);
}
}
for (int i = 0; i < verts2.Count; i++)
{
Vector2 vert = verts2[i];
if (PointInPoly(vert, new List <Vector2>(verts1)))
{
return(true);
}
}
//check to see if any of the edges of a polygon intersect with the edges of the other
//this code ensures concave shapes work too but it's potentially slow
LineSeg lnsCheck = new LineSeg();
int j = verts1.Count - 1;
for (int i = 0; i < verts1.Count; i++)
{
lnsCheck.SetA(verts1[i]);
lnsCheck.SetB(verts1[j]);
if (LineSegIntersectsPoly(lnsCheck, verts2))
{
return(true);
}
j = i;
}
return(false);
}
///Returns whether a point lies on the perimeter of a polygon given its vertices
public static bool PointOnPolyPerimeter(Vector2 p, List <Vector2> verts)
{
LineSeg lineCheck = new LineSeg();
int j = verts.Count - 1;
//checks every line segment of the polygon to see if the point lies on any segment
for (int i = 0; i < verts.Count; i++)
{
lineCheck.SetA(verts[i]);
lineCheck.SetB(verts[j]);
if (PointOnLineSeg(p, lineCheck))
{
return(true);
}
j = i;
}
return(false);
}
///Returns whether a circle intersects a polygon (given a list of vertices)
public static bool CircleIntersectsPoly(Circle c, List <Vector2> verts)
{
//check to see if the center of the circle is in the poly
if (PointInPoly(c.WorldCenter, verts))
{
return(true);
}
//check to see if any points are in the circle
for (int i = 0; i < verts.Count; i++)
{
Vector2 vert = verts[i];
if (PointInCircle(vert, c))
{
return(true);
}
}
LineSeg lnsCheck = new LineSeg();
int j = verts.Count - 1;
//check each line segment of the polygon until an intersection is found
for (int i = 0; i < verts.Count; i++)
{
lnsCheck.SetA(verts[i]);
lnsCheck.SetB(verts[j]);
if (LineSegIntersectsCircle(lnsCheck, c))
{
return(true);
}
j = i;
}
return(false);
}