/// <summary>
/// Marching squares over the given domain using the mesh defined via the dimensions
/// (wid,hei) to build a set of polygons such that f(x,y) less than 0, using the given number
/// 'bin' for recursive linear inteprolation along cell boundaries.
///
/// if 'comb' is true, then the polygons will also be composited into larger possible concave
/// polygons.
/// </summary>
/// <param name="domain"></param>
/// <param name="cellWidth"></param>
/// <param name="cellHeight"></param>
/// <param name="f"></param>
/// <param name="lerpCount"></param>
/// <param name="combine"></param>
/// <returns></returns>
public static List <Vertices> DetectSquares(Box2D.AABB domain, float cellWidth, float cellHeight, sbyte[,] f,
int lerpCount, bool combine)
{
CxFastList <GeomPoly> ret = new CxFastList <GeomPoly>();
List <Vertices> verticesList = new List <Vertices>();
//NOTE: removed assignments as they were not used.
List <GeomPoly> polyList;
GeomPoly gp;
int xn = (int)(domain.GetExtents().x * 2 / cellWidth);
bool xp = xn == (domain.GetExtents().x * 2 / cellWidth);
int yn = (int)(domain.GetExtents().y * 2 / cellHeight);
bool yp = yn == (domain.GetExtents().y * 2 / cellHeight);
if (!xp)
{
xn++;
}
if (!yp)
{
yn++;
}
sbyte[,] fs = new sbyte[xn + 1, yn + 1];
GeomPolyVal[,] ps = new GeomPolyVal[xn + 1, yn + 1];
//populate shared function lookups.
for (int x = 0; x < xn + 1; x++)
{
int x0;
if (x == xn)
{
x0 = (int)domain.upperBound.x;
}
else
{
x0 = (int)(x * cellWidth + domain.lowerBound.x);
}
for (int y = 0; y < yn + 1; y++)
{
int y0;
if (y == yn)
{
y0 = (int)domain.upperBound.y;
}
else
{
y0 = (int)(y * cellHeight + domain.lowerBound.y);
}
fs[x, y] = f[x0, y0];
}
}
//generate sub-polys and combine to scan lines
for (int y = 0; y < yn; y++)
{
float y0 = y * cellHeight + domain.lowerBound.y;
float y1;
if (y == yn - 1)
{
y1 = domain.upperBound.y;
}
else
{
y1 = y0 + cellHeight;
}
GeomPoly pre = null;
for (int x = 0; x < xn; x++)
{
float x0 = x * cellWidth + domain.lowerBound.x;
float x1;
if (x == xn - 1)
{
x1 = domain.upperBound.x;
}
else
{
x1 = x0 + cellWidth;
}
gp = new GeomPoly();
int key = MarchSquare(f, fs, ref gp, x, y, x0, y0, x1, y1, lerpCount);
if (gp.Length != 0)
{
if (combine && pre != null && (key & 9) != 0)
{
combLeft(ref pre, ref gp);
gp = pre;
}
else
{
ret.Add(gp);
}
ps[x, y] = new GeomPolyVal(gp, key);
}
else
{
gp = null;
}
pre = gp;
}
}
if (!combine)
{
polyList = ret.GetListOfElements();
foreach (GeomPoly poly in polyList)
{
verticesList.Add(new Vertices(poly.Points.GetListOfElements()));
}
return(verticesList);
}
//combine scan lines together
for (int y = 1; y < yn; y++)
{
int x = 0;
while (x < xn)
{
GeomPolyVal p = ps[x, y];
//skip along scan line if no polygon exists at this point
if (p == null)
{
x++;
continue;
}
//skip along if current polygon cannot be combined above.
if ((p.Key & 12) == 0)
{
x++;
continue;
}
//skip along if no polygon exists above.
GeomPolyVal u = ps[x, y - 1];
if (u == null)
{
x++;
continue;
}
//skip along if polygon above cannot be combined with.
if ((u.Key & 3) == 0)
{
x++;
continue;
}
float ax = x * cellWidth + domain.lowerBound.x;
float ay = y * cellHeight + domain.lowerBound.y;
CxFastList <FVector2> bp = p.GeomP.Points;
CxFastList <FVector2> ap = u.GeomP.Points;
//skip if it's already been combined with above polygon
if (u.GeomP == p.GeomP)
{
x++;
continue;
}
//combine above (but disallow the hole thingies
CxFastListNode <FVector2> bi = bp.Begin();
while (Square(bi.Elem().Y - ay) > Box2D.Settings.b2_epsilon || bi.Elem().X < ax)
{
bi = bi.Next();
}
//NOTE: Unused
//Vector2 b0 = bi.elem();
FVector2 b1 = bi.Next().Elem();
if (Square(b1.Y - ay) > Box2D.Settings.b2_epsilon)
{
x++;
continue;
}
bool brk = true;
CxFastListNode <FVector2> ai = ap.Begin();
while (ai != ap.End())
{
if (VecDsq(ai.Elem(), b1) < Box2D.Settings.b2_epsilon)
{
brk = false;
break;
}
ai = ai.Next();
}
if (brk)
{
x++;
continue;
}
CxFastListNode <FVector2> bj = bi.Next().Next();
if (bj == bp.End())
{
bj = bp.Begin();
}
while (bj != bi)
{
ai = ap.Insert(ai, bj.Elem()); // .clone()
bj = bj.Next();
if (bj == bp.End())
{
bj = bp.Begin();
}
u.GeomP.Length++;
}
//u.p.simplify(float.Epsilon,float.Epsilon);
//
ax = x + 1;
while (ax < xn)
{
GeomPolyVal p2 = ps[(int)ax, y];
if (p2 == null || p2.GeomP != p.GeomP)
{
ax++;
continue;
}
p2.GeomP = u.GeomP;
ax++;
}
ax = x - 1;
while (ax >= 0)
{
GeomPolyVal p2 = ps[(int)ax, y];
if (p2 == null || p2.GeomP != p.GeomP)
{
ax--;
continue;
}
p2.GeomP = u.GeomP;
ax--;
}
ret.Remove(p.GeomP);
p.GeomP = u.GeomP;
x = (int)((bi.Next().Elem().X - domain.lowerBound.x) / cellWidth) + 1;
//x++; this was already commented out!
}
}
polyList = ret.GetListOfElements();
foreach (GeomPoly poly in polyList)
{
verticesList.Add(new Vertices(poly.Points.GetListOfElements()));
}
return(verticesList);
}
/// <summary>
/// Get all intersections between a line segment and an AABB.
/// </summary>
/// <param name="point1">The first point of the line segment to test</param>
/// <param name="point2">The second point of the line segment to test.</param>
/// <param name="aabb">The AABB that is used for testing intersection.</param>
/// <param name="intersectionPoints">An list of intersection points. Any intersection points found will be added to this list.</param>
public static void LineSegmentAABBIntersect(ref FVector2 point1, ref FVector2 point2, Box2D.AABB aabb,
ref List <FVector2> intersectionPoints)
{
// LineSegmentVerticesIntersect(ref point1, ref point2, aabb.vVertices, ref intersectionPoints);
}
