// 从三角序列创建矢量图层
static GeomLayer FromTriangles(IEnumerable <Triangle> triangles, List <GeomPoint> originalPoints)
{
// 创建字典用于反查
var pt_mapper = new Dictionary <Vector2, GeomPoint>();
foreach (GeomPoint tmp in originalPoints)
{
pt_mapper[tmp] = tmp;
}
// 构造矢量图层
GeomLayer result = new GeomLayer(GeomType.Polygon);
var g_points = new Dictionary <Vector2, GeomPoint>();
var g_arcs = new Dictionary <Edge, GeomArc>();
int point_cnt = 0, arc_cnt = 0, poly_cnt = 0;
foreach (Triangle tri in triangles)
{
// 按需创建点
foreach (Vector2 tmp in tri.Points())
{
if (!g_points.ContainsKey(tmp))
{
var new_point = pt_mapper[tmp].Copy(); // 反查原始数据
new_point.id = ++point_cnt;
g_points[tmp] = new_point;
}
}
// 去重获取三边
var arcs = new List <GeomArc>();
foreach (var tmp in tri.Edges())
{
GeomArc cur_arc;
if (g_arcs.ContainsKey(tmp))
{
cur_arc = g_arcs[tmp];
}
else
{
cur_arc = new GeomArc(new GeomPoint[] { g_points[tmp.Item1], g_points[tmp.Item2] }, ++arc_cnt);
g_arcs[tmp] = g_arcs[tmp.Reverse()] = cur_arc;
}
arcs.Add(cur_arc);
}
// 创建三角形
GeomPoly tri_poly = new GeomPoly(arcs, ++poly_cnt);
result.polygons.Add(tri_poly);
}
// 加入点集、边集
result.points.AddRange(g_points.Values);
result.arcs.AddRange(g_arcs.Values);
return(result);
}
/** 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.
**/
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;
}
// 2.1 从指定弧段与端点开始搜索相连多边形
static void PolyTopoGroup(GeomPoint pt, GeomArc arc)
{
inners = new HashSet <GeomPoly>();
stack = new LinkedList <Tuple <GeomPoint, GeomArc> >();
stack.AddFirst(new Tuple <GeomPoint, GeomArc>(pt, arc));
while (stack.Count > 0)
{
var data = stack.First;
stack.RemoveFirst();
PolyTopoUnit(data.Value);
}
if (inners.Count == 0)
{
return;
}
// 获取并删除外包多边形（面积最大）
GeomPoly outer = null;
if (inners.Count > 1)
{
outer = null;
foreach (var poly in inners)
{
if (outer == null || outer.OuterArea < poly.OuterArea)
{
outer = poly;
}
}
inners.Remove(outer);
}
else
{
outer = inners.First();
}
// 加入待处理孔洞列表
holesGroup.Add(new Tuple <GeomPoly, HashSet <GeomPoly> >(outer, inners));
cPoly.AddRange(inners);
}
// 2.1.1 搜索相连多边形：单元操作，返回当前搜索
static void PolyTopoUnit(Tuple <GeomPoint, GeomArc> data)
{
if (arcUsed.Contains(data))
{
return;
}
var res = new List <Tuple <GeomPoint, GeomArc> >();
// 搜索直到首尾相接
while (true)
{
// 加入当前弧段
res.Add(data);
arcUsed.Add(data);
// 获取下一弧段
GeomPoint prevPt = data.Item1;
GeomArc prevArc = data.Item2;
GeomPoint nextPt = prevArc.First;
if (nextPt == prevPt)
{
nextPt = prevArc.Last;
}
GeomArc nextArc = vertNext[nextPt][data.Item2];
data = new Tuple <GeomPoint, GeomArc>(nextPt, prevArc); // 同弧段不同顶点
if (!arcUsed.Contains(data))
{
stack.AddFirst(data);
}
data = new Tuple <GeomPoint, GeomArc>(nextPt, nextArc);
// 首尾相接时跳出
if (data.Equals(res[0]))
{
break;
}
}
// 创造多边形
var newPoly = new GeomPoly(from pair in res select pair.Item2);
inners.Add(newPoly);
}
public GeomPolyVal(GeomPoly geomP, int K)
{
GeomP = geomP;
Key = K;
}
/** Used in polygon composition to composit polygons into scan lines
* Combining polya and polyb into one super-polygon stored in polya.
**/
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.Elem();
CxFastListNode <Vector2> prea = null;
while (ai != ap.End())
{
Vector2 a = ai.Elem();
if (VecDsq(a, b) < Settings.Epsilon)
{
//ignore shared vertex if parallel
if (prea != null)
{
Vector2 a0 = prea.Elem();
b = bi.Next().Elem();
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 < Settings.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.Next();
Vector2 a1 = ai.Elem();
ai = ai.Next();
if (ai == ap.End())
{
ai = ap.Begin();
}
Vector2 a2 = ai.Elem();
Vector2 a00 = preb.Elem();
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 < Settings.Epsilon)
{
ap.Erase(preb, preb.Next());
polya.Length--;
}
return;
}
prea = ai;
ai = ai.Next();
}
}
/// <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.Elem().Y - ay) > Settings.Epsilon || bi.Elem().X < ax)
{
bi = bi.Next();
}
//NOTE: Unused
//Vector2 b0 = bi.elem();
Vector2 b1 = bi.Next().Elem();
if (Square(b1.Y - ay) > Settings.Epsilon)
{
x++;
continue;
}
bool brk = true;
CxFastListNode <Vector2> ai = ap.Begin();
while (ai != ap.End())
{
if (VecDsq(ai.Elem(), b1) < Settings.Epsilon)
{
brk = false;
break;
}
ai = ai.Next();
}
if (brk)
{
x++;
continue;
}
CxFastListNode <Vector2> 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);
}
/** 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.
**/
private static int MarchSquare(sbyte[,] f, sbyte[,] fs, ref GeomPoly poly, int ax, int ay, GGame.Math.Fix64 x0, GGame.Math.Fix64 y0,
GGame.Math.Fix64 x1, GGame.Math.Fix64 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(GGame.Math.Fix64.Epsilon,GGame.Math.Fix64.Epsilon);
}
return(key);
}
public GeomPolyVal(GeomPoly geomP, int K)
{
this.GeomP = geomP;
this.Key = K;
}
public GeomPolyVal(GeomPoly P, int K)
{
p = P;
key = K;
}
/// <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) < 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="cell_width"></param>
/// <param name="cell_height"></param>
/// <param name="f"></param>
/// <param name="lerp_count"></param>
/// <param name="combine"></param>
/// <returns></returns>
public static List <Vertices> DetectSquares(AABB domain, float cell_width, float cell_height, sbyte[,] f, int lerp_count, bool combine)
{
var ret = new CxFastList <GeomPoly>();
List <Vertices> verticesList = new List <Vertices>();
List <GeomPoly> polyList = ret.GetListOfElements();
GeomPoly gp = new GeomPoly();
var xn = (int)(domain.Extents.X * 2 / cell_width); var xp = xn == (domain.Extents.X * 2 / cell_width);
var yn = (int)(domain.Extents.Y * 2 / cell_height); var yp = yn == (domain.Extents.Y * 2 / cell_height);
if (!xp)
{
xn++;
}
if (!yp)
{
yn++;
}
var fs = new sbyte[xn + 1, yn + 1];
var 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 * cell_width + 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 * cell_height + domain.LowerBound.Y);
}
fs[x, y] = f[x0, y0];
}
}
//generate sub-polys and combine to scan lines
for (int y = 0; y < yn; y++)
{
var y0 = y * cell_height + domain.LowerBound.Y; float y1; if (y == yn - 1)
{
y1 = domain.UpperBound.Y;
}
else
{
y1 = y0 + cell_height;
}
GeomPoly pre = null;
for (int x = 0; x < xn; x++)
{
var x0 = x * cell_width + domain.LowerBound.X; float x1; if (x == xn - 1)
{
x1 = domain.UpperBound.X;
}
else
{
x1 = x0 + cell_width;
}
gp = new GeomPoly();
var key = marchSquare(f, fs, ref gp, x, y, x0, y0, x1, y1, lerp_count);
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 (var poly in polyList)
{
verticesList.Add(new Vertices(poly.points.GetListOfElements()));
}
return(verticesList);
}
//combine scan lines together
for (int y = 1; y < yn; y++)
{
var x = 0;
while (x < xn)
{
var 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.
var 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;
}
var ax = x * cell_width + domain.LowerBound.X;
var ay = y * cell_height + domain.LowerBound.Y;
var bp = p.p.points;
var ap = u.p.points;
//skip if it's already been combined with above polygon
if (u.p == p.p)
{
x++; continue;
}
//combine above (but disallow the hole thingies
var bi = bp.begin();
while (square(bi.elem().Y - ay) > float.Epsilon || bi.elem().X < ax)
{
bi = bi.next();
}
Vector2 b0 = bi.elem();
var b1 = bi.next().elem();
if (square(b1.Y - ay) > float.Epsilon)
{
x++; continue;
}
var brk = true;
var ai = ap.begin();
while (ai != ap.end())
{
if (vec_dsq(ai.elem(), b1) < float.Epsilon)
{
brk = false;
break;
}
ai = ai.next();
}
if (brk)
{
x++; continue;
}
var 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.p.length++;
}
//u.p.simplify(float.Epsilon,float.Epsilon);
//
ax = x + 1;
while (ax < xn)
{
var p2 = ps[(int)ax, y];
if (p2 == null || p2.p != p.p)
{
ax++; continue;
}
p2.p = u.p;
ax++;
}
ax = x - 1;
while (ax >= 0)
{
var p2 = ps[(int)ax, y];
if (p2 == null || p2.p != p.p)
{
ax--; continue;
}
p2.p = u.p;
ax--;
}
ret.remove(p.p);
p.p = u.p;
x = (int)((bi.next().elem().X - domain.LowerBound.X) / cell_width) + 1;
//x++; this was already commented out!
}
}
polyList = ret.GetListOfElements();
foreach (var poly in polyList)
{
verticesList.Add(new Vertices(poly.points.GetListOfElements()));
}
return(verticesList);
}
/** Used in polygon composition to composit polygons into scan lines
* Combining polya and polyb into one super-polygon stored in polya.
**/
private static void combLeft(ref GeomPoly polya, ref GeomPoly polyb)
{
var ap = polya.points;
var bp = polyb.points;
var ai = ap.begin();
var bi = bp.begin();
var b = bi.elem();
CxFastListNode <Vector2> prea = null;
while (ai != ap.end())
{
var a = ai.elem();
if (vec_dsq(a, b) < float.Epsilon)
{
//ignore shared vertex if parallel
if (prea != null)
{
var a0 = prea.elem();
b = bi.next().elem();
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);
var dot = vec_cross(u, v);
if (dot * dot < float.Epsilon)
{
ap.erase(prea, ai);
polya.length--;
ai = prea;
}
}
//insert polyb into polya
var fst = true;
CxFastListNode <Vector2> preb = null;
while (!bp.empty())
{
var 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.next();
var a1 = ai.elem();
ai = ai.next(); if (ai == ap.end())
{
ai = ap.begin();
}
var a2 = ai.elem();
var a00 = preb.elem();
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);
var dot1 = vec_cross(uu, vv);
if (dot1 * dot1 < float.Epsilon)
{
ap.erase(preb, preb.next());
polya.length--;
}
return;
}
prea = ai;
ai = ai.next();
}
}
/** 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.
**/
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
var key = 0;
var v0 = fs[ax, ay]; if (v0 < 0)
{
key |= 8;
}
var v1 = fs[ax + 1, ay]; if (v1 < 0)
{
key |= 4;
}
var v2 = fs[ax + 1, ay + 1]; if (v2 < 0)
{
key |= 2;
}
var v3 = fs[ax, ay + 1]; if (v3 < 0)
{
key |= 1;
}
var val = look_march[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);
}
// 比较多边形外包面积大小 static int CompArea(GeomPoly p1, GeomPoly p2) => Math.Sign(p1.OuterArea - p2.OuterArea);
