// This calculates the relative angle between two lines
private double CalculateRelativeAngle(Linedef a, Linedef b)
{
// Determine angles
double ana = a.Angle; if (a.End == basevertex)
{
ana += Angle2D.PI;
}
double anb = b.Angle; if (b.End == basevertex)
{
anb += Angle2D.PI;
}
// Take the difference from angles
double n = Angle2D.Difference(ana, anb);
// Get line end vertices a and b that are not connected to basevertex
Vector2D va = (a.Start == basevertex ? a.End.Position : a.Start.Position);
Vector2D vb = (b.Start == basevertex ? b.End.Position : b.Start.Position);
// Check to which side the angle goes and adjust angle as needed
double s = Line2D.GetSideOfLine(va, vb, basevertex.Position);
if (((s < 0) && front) || ((s > 0) && !front))
{
n = Angle2D.PI2 - n;
}
// Return result
return(n);
}
// This checks if a point is inside a triangle
// When the point is on an edge of the triangle, it depends on the lines
// adjacent to the point if it is considered inside or not
// NOTE: vertices in t must be in clockwise order!
private static bool PointInsideTriangle(EarClipVertex[] t, LinkedListNode <EarClipVertex> p)
{
// If the triangle has no area, there can never be a point inside
if (TriangleHasArea(t))
{
float lineside01 = Line2D.GetSideOfLine(t[0].Position, t[1].Position, p.Value.Position);
float lineside12 = Line2D.GetSideOfLine(t[1].Position, t[2].Position, p.Value.Position);
float lineside20 = Line2D.GetSideOfLine(t[2].Position, t[0].Position, p.Value.Position);
float u_on_line = 0.5f;
// If point p is on the line of an edge, find out where on the edge segment p is.
if (lineside01 == 0.0f)
{
u_on_line = Line2D.GetNearestOnLine(t[0].Position, t[1].Position, p.Value.Position);
}
else if (lineside12 == 0.0f)
{
u_on_line = Line2D.GetNearestOnLine(t[1].Position, t[2].Position, p.Value.Position);
}
else if (lineside20 == 0.0f)
{
u_on_line = Line2D.GetNearestOnLine(t[2].Position, t[0].Position, p.Value.Position);
}
// If any of the lineside results are 0 then that means the point p lies on that edge and we
// need to test if the lines adjacent to the point p are in the triangle or not.
// If the lines are intersecting the triangle, we also consider the point inside.
if ((lineside01 == 0.0f) || (lineside12 == 0.0f) || (lineside20 == 0.0f))
{
// When the point p is outside the edge segment, then it is not inside the triangle
if ((u_on_line < 0.0f) || (u_on_line > 1.0f))
{
return(false);
}
// Point p is on an edge segment. We'll have to decide by it's lines if we call it inside or outside the triangle.
LinkedListNode <EarClipVertex> p1 = p.Previous ?? p.List.Last;
LinkedListNode <EarClipVertex> p2 = p.Next ?? p.List.First;
if (LineInsideTriangle(t, p.Value.Position, p1.Value.Position))
{
return(true);
}
if (LineInsideTriangle(t, p.Value.Position, p2.Value.Position))
{
return(true);
}
return(false);
}
else
{
return((lineside01 < 0.0f) && (lineside12 < 0.0f) && (lineside20 < 0.0f));
}
}
else
{
return(false);
}
}
// This calculates the relative angle between two sides
private float CalculateRelativeAngle(Sidedef a, Sidedef b)
{
float s, n, ana, anb;
Vector2D va, vb;
bool dir;
// Determine angles
ana = a.Line.Angle; if (a.Line.End == basevertex)
{
ana += Angle2D.PI;
}
anb = b.Line.Angle; if (b.Line.End == basevertex)
{
anb += Angle2D.PI;
}
// Take the difference from angles
n = Angle2D.Difference(ana, anb);
// Get line end vertices a and b that are not connected to basevertex
if (a.Line.Start == basevertex)
{
va = a.Line.End.Position;
}
else
{
va = a.Line.Start.Position;
}
if (b.Line.Start == basevertex)
{
vb = b.Line.End.Position;
}
else
{
vb = b.Line.Start.Position;
}
// Determine rotation direction
dir = baseside.IsFront;
if (baseside.Line.End == basevertex)
{
dir = !dir;
}
// Check to which side the angle goes and adjust angle as needed
s = Line2D.GetSideOfLine(va, vb, basevertex.Position);
if ((s < 0) && dir)
{
n = Angle2D.PI2 - n;
}
if ((s > 0) && !dir)
{
n = Angle2D.PI2 - n;
}
// Return result
return(n);
}
public double GetSideOfLine(Vector2D p)
{
return(Line2D.GetSideOfLine(v1, v2, p));
}
// This checks if a vertex is reflex (corner > 180 deg) or convex (corner < 180 deg)
private static bool IsReflex(EarClipVertex[] t)
{
// Return true when corner is > 180 deg
return(Line2D.GetSideOfLine(t[0].Position, t[2].Position, t[1].Position) < 0.0f);
}
// This checks if a line is inside a triangle (touching the triangle is allowed)
// NOTE: We already know p1 is on an edge segment of the triangle
private static bool LineInsideTriangle(EarClipVertex[] t, Vector2D p1, Vector2D p2)
{
float s01 = Line2D.GetSideOfLine(t[0].Position, t[1].Position, p2);
float s12 = Line2D.GetSideOfLine(t[1].Position, t[2].Position, p2);
float s20 = Line2D.GetSideOfLine(t[2].Position, t[0].Position, p2);
float p2_on_edge = 2.0f; // somewhere outside the 0 .. 1 range
float p1_on_same_edge = 2.0f;
// Test if p2 is inside the triangle
if ((s01 < 0.0f) && (s12 < 0.0f) && (s20 < 0.0f))
{
// Line is inside triangle, because p2 is
return(true);
}
// Test if p2 is on an edge of the triangle and if it is we would
// like to know where on the edge segment p2 is
else if (s01 == 0.0f)
{
p2_on_edge = Line2D.GetNearestOnLine(t[0].Position, t[1].Position, p2);
p1_on_same_edge = Line2D.GetSideOfLine(t[0].Position, t[1].Position, p1);
}
else if (s12 == 0.0f)
{
p2_on_edge = Line2D.GetNearestOnLine(t[1].Position, t[2].Position, p2);
p1_on_same_edge = Line2D.GetSideOfLine(t[1].Position, t[2].Position, p1);
}
else if (s20 == 0.0f)
{
p2_on_edge = Line2D.GetNearestOnLine(t[2].Position, t[0].Position, p2);
p1_on_same_edge = Line2D.GetSideOfLine(t[2].Position, t[0].Position, p1);
}
// Is p2 actually on the edge segment?
if ((p2_on_edge >= 0.0f) && (p2_on_edge <= 1.0f))
{
// If p1 is on the same edge (or the unlimited line of that edge)
// then the line is not inside this triangle.
if (p1_on_same_edge == 0.0f)
{
return(false);
}
}
// Do a complete line-triangle intersection test
// We already know p1 is not inside the triangle (possibly on an edge)
Line2D p = new Line2D(p1, p2);
Line2D t01 = new Line2D(t[0].Position, t[1].Position);
Line2D t12 = new Line2D(t[1].Position, t[2].Position);
Line2D t20 = new Line2D(t[2].Position, t[0].Position);
float pu, pt;
// Test intersections
t01.GetIntersection(p, out pu, out pt);
if (!float.IsNaN(pu) && (pu >= 0.0f) && (pu <= 1.0f) && (pt >= 0.0f) && (pt <= 1.0f))
{
return(true);
}
t12.GetIntersection(p, out pu, out pt);
if (!float.IsNaN(pu) && (pu >= 0.0f) && (pu <= 1.0f) && (pt >= 0.0f) && (pt <= 1.0f))
{
return(true);
}
t20.GetIntersection(p, out pu, out pt);
if (!float.IsNaN(pu) && (pu >= 0.0f) && (pu <= 1.0f) && (pt >= 0.0f) && (pt <= 1.0f))
{
return(true);
}
return(false);
}
// This checks if a given ear is a valid (no intersections from reflex vertices)
private static bool CheckValidEar(EarClipVertex[] t, LinkedList <EarClipVertex> reflexes)
{
//mxd
Vector2D pos0 = t[0].Position;
Vector2D pos1 = t[1].Position;
Vector2D pos2 = t[2].Position;
Vector2D vpos;
LinkedListNode <EarClipVertex> p;
// Go for all reflex vertices
foreach (EarClipVertex rv in reflexes)
{
// Not one of the triangle corners?
if ((rv.Position != pos0) && (rv.Position != pos1) && (rv.Position != pos2))
{
// Return false on intersection
// This checks if a point is inside a triangle
// When the point is on an edge of the triangle, it depends on the lines
// adjacent to the point if it is considered inside or not
// NOTE: vertices in t must be in clockwise order!
// If the triangle has no area, there can never be a point inside
if (TriangleHasArea(t))
{
//mxd
pos0 = t[0].Position;
pos1 = t[1].Position;
pos2 = t[2].Position;
p = rv.MainListNode;
vpos = p.Value.Position;
//mxd. Check bounds first...
if (vpos.x < Math.Min(pos0.x, Math.Min(pos1.x, pos2.x)) ||
vpos.x > Math.Max(pos0.x, Math.Max(pos1.x, pos2.x)) ||
vpos.y < Math.Min(pos0.y, Math.Min(pos1.y, pos2.y)) ||
vpos.y > Math.Max(pos0.y, Math.Max(pos1.y, pos2.y)))
{
continue;
}
double lineside01 = Line2D.GetSideOfLine(pos0, pos1, vpos);
double lineside12 = Line2D.GetSideOfLine(pos1, pos2, vpos);
double lineside20 = Line2D.GetSideOfLine(pos2, pos0, vpos);
double u_on_line = 0.5f;
// If point p is on the line of an edge, find out where on the edge segment p is.
if (lineside01 == 0.0f)
{
u_on_line = Line2D.GetNearestOnLine(pos0, pos1, vpos);
}
else if (lineside12 == 0.0f)
{
u_on_line = Line2D.GetNearestOnLine(pos1, pos2, vpos);
}
else if (lineside20 == 0.0f)
{
u_on_line = Line2D.GetNearestOnLine(pos2, pos0, vpos);
}
// If any of the lineside results are 0 then that means the point p lies on that edge and we
// need to test if the lines adjacent to the point p are in the triangle or not.
// If the lines are intersecting the triangle, we also consider the point inside.
if (lineside01 == 0.0f || lineside12 == 0.0f || lineside20 == 0.0f)
{
// When the point p is outside the edge segment, then it is not inside the triangle
if (u_on_line < 0.0f || u_on_line > 1.0f)
{
continue;
}
// Point p is on an edge segment. We'll have to decide by it's lines if we call it inside or outside the triangle.
LinkedListNode <EarClipVertex> p1 = p.Previous ?? p.List.Last;
if (LineInsideTriangle(t, vpos, p1.Value.Position))
{
return(false);
}
LinkedListNode <EarClipVertex> p2 = p.Next ?? p.List.First;
if (LineInsideTriangle(t, vpos, p2.Value.Position))
{
return(false);
}
continue;
}
if (lineside01 < 0.0f && lineside12 < 0.0f && lineside20 < 0.0f)
{
return(false);
}
}
}
}
// Valid ear!
return(true);
}
public float GetSideOfLine(Vector2D p)
{
return(Line2D.GetSideOfLine(v1, v2, p));
}
