/// <summary>
/// Initializes a new instance of the <see cref="GeomPolyVal" /> class
/// </summary>
/// <param name="geomP">The geom</param>
/// <param name="k">The </param>
public GeomPolyVal(GeomPoly geomP, int k)
{
GeomP = geomP;
Key = k;
}
/// <summary>
/// Used in polygon composition to composit polygons into scan lines Combining polya and polyb into one
/// super-polygon stored in polya.
/// </summary>
private static void CombLeft(ref GeomPoly polya, ref GeomPoly polyb)
{
CxFastList <Vector2> ap = polya.Points;
CxFastList <Vector2> bp = polyb.Points;
CxFastListNode <Vector2> ai = ap.Begin();
CxFastListNode <Vector2> bi = bp.Begin();
Vector2 b = bi.GetElem();
CxFastListNode <Vector2> prea = null;
while (ai != ap.End())
{
Vector2 a = ai.GetElem();
if (VecDsq(a, b) < MathConstants.Epsilon)
{
//ignore shared vertex if parallel
if (prea != null)
{
Vector2 a0 = prea.GetElem();
b = bi.GetNext().GetElem();
Vector2 u = a - a0;
//vec_new(u); vec_sub(a.p.p, a0.p.p, u);
Vector2 v = b - a;
//vec_new(v); vec_sub(b.p.p, a.p.p, v);
float dot = VecCross(u, v);
if (dot * dot < MathConstants.Epsilon)
{
ap.Erase(prea, ai);
polya.Length--;
ai = prea;
}
}
//insert polyb into polya
bool fst = true;
CxFastListNode <Vector2> preb = null;
while (!bp.Empty())
{
Vector2 bb = bp.Front();
bp.Pop();
if (!fst && !bp.Empty())
{
ai = ap.Insert(ai, bb);
polya.Length++;
preb = ai;
}
fst = false;
}
//ignore shared vertex if parallel
ai = ai.GetNext();
Vector2 a1 = ai.GetElem();
ai = ai.GetNext();
if (ai == ap.End())
{
ai = ap.Begin();
}
Vector2 a2 = ai.GetElem();
Vector2 a00 = preb.GetElem();
Vector2 uu = a1 - a00;
//vec_new(u); vec_sub(a1.p, a0.p, u);
Vector2 vv = a2 - a1;
//vec_new(v); vec_sub(a2.p, a1.p, v);
float dot1 = VecCross(uu, vv);
if (dot1 * dot1 < MathConstants.Epsilon)
{
ap.Erase(preb, preb.GetNext());
polya.Length--;
}
return;
}
prea = ai;
ai = ai.GetNext();
}
}
/// <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(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.Extents.X * 2 / cellWidth);
bool xp = xn == domain.Extents.X * 2 / cellWidth;
int yn = (int)(domain.Extents.Y * 2 / cellHeight);
bool yp = yn == domain.Extents.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 <Vector2> bp = p.GeomP.Points;
CxFastList <Vector2> 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 <Vector2> bi = bp.Begin();
while (Square(bi.GetElem().Y - ay) > MathConstants.Epsilon || bi.GetElem().X < ax)
{
bi = bi.GetNext();
}
//NOTE: Unused
//Vector2 b0 = bi.elem();
Vector2 b1 = bi.GetNext().GetElem();
if (Square(b1.Y - ay) > MathConstants.Epsilon)
{
x++;
continue;
}
bool brk = true;
CxFastListNode <Vector2> ai = ap.Begin();
while (ai != ap.End())
{
if (VecDsq(ai.GetElem(), b1) < MathConstants.Epsilon)
{
brk = false;
break;
}
ai = ai.GetNext();
}
if (brk)
{
x++;
continue;
}
CxFastListNode <Vector2> bj = bi.GetNext().GetNext();
if (bj == bp.End())
{
bj = bp.Begin();
}
while (bj != bi)
{
ai = ap.Insert(ai, bj.GetElem()); // .clone()
bj = bj.GetNext();
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.GetNext().GetElem().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>
/// Look-up table to relate polygon key with the vertices that should be used for the sub polygon in marching
/// squares Perform a single celled marching square for for the given cell defined by (x0,y0) (x1,y1) using the
/// function f
/// for recursive interpolation, given the look-up table 'fs' of the values of 'f' at cell vertices with the result to
/// be
/// stored in 'poly' given the actual coordinates of 'ax' 'ay' in the marching squares mesh.
/// </summary>
private static int MarchSquare(sbyte[,] f, sbyte[,] fs, ref GeomPoly poly, int ax, int ay, float x0, float y0,
float x1, float y1, int bin)
{
//key lookup
int key = 0;
sbyte v0 = fs[ax, ay];
if (v0 < 0)
{
key |= 8;
}
sbyte v1 = fs[ax + 1, ay];
if (v1 < 0)
{
key |= 4;
}
sbyte v2 = fs[ax + 1, ay + 1];
if (v2 < 0)
{
key |= 2;
}
sbyte v3 = fs[ax, ay + 1];
if (v3 < 0)
{
key |= 1;
}
int val = LookMarch[key];
if (val != 0)
{
CxFastListNode <Vector2> pi = null;
for (int i = 0; i < 8; i++)
{
Vector2 p;
if ((val & (1 << i)) != 0)
{
if (i == 7 && (val & 1) == 0)
{
poly.Points.Add(p = new Vector2(x0, Ylerp(y0, y1, x0, v0, v3, f, bin)));
}
else
{
if (i == 0)
{
p = new Vector2(x0, y0);
}
else if (i == 2)
{
p = new Vector2(x1, y0);
}
else if (i == 4)
{
p = new Vector2(x1, y1);
}
else if (i == 6)
{
p = new Vector2(x0, y1);
}
else if (i == 1)
{
p = new Vector2(Xlerp(x0, x1, y0, v0, v1, f, bin), y0);
}
else if (i == 5)
{
p = new Vector2(Xlerp(x0, x1, y1, v3, v2, f, bin), y1);
}
else if (i == 3)
{
p = new Vector2(x1, Ylerp(y0, y1, x1, v1, v2, f, bin));
}
else
{
p = new Vector2(x0, Ylerp(y0, y1, x0, v0, v3, f, bin));
}
pi = poly.Points.Insert(pi, p);
}
poly.Length++;
}
}
//poly.simplify(float.Epsilon,float.Epsilon);
}
return(key);
}
