/// <summary>
/// 构建当前缩放层级的瓦片
/// </summary>
/// <param name="bound"></param>
/// <param name="zoom"></param>
void Build(GBound bound, int zoom)
{
int _tileSize = Projection.TileSize;
//构建裁剪边界的矩形，用于整体裁剪
IGeometry _boundGeometry = bound.ToInsertPolygon();
//瓦片多尺度缓存
if (TileDictionary.ContainsKey(zoom))
{
TileDictionary[zoom].Clear();
}
else
{
TileDictionary[zoom] = new List <GTileElement>();
}
//1.获取坐上右下坐标
Coordinate p0 = bound.Min;
Coordinate p1 = bound.Max;
//2.分尺度计算格网位置
//2.1 转换成尺度下的pixel
Coordinate min = Projection.LatlngToPoint(p0, zoom);
Coordinate max = Projection.LatlngToPoint(p1, zoom);
//2.2 计算pixel下边界范围
GBound pixelBound = new GBound(new List <Coordinate>()
{
min, max
});
//2.3 通过pixelbound计算range
GBound range = new GBound(new List <Coordinate>()
{
new Coordinate((int)Math.Floor(pixelBound.Min.X / _tileSize), (int)Math.Floor(pixelBound.Min.Y / _tileSize)),
new Coordinate((int)Math.Ceiling(pixelBound.Max.X / _tileSize) - 1, (int)Math.Ceiling(pixelBound.Max.Y / _tileSize) - 1),
});
//2.3统计区域内瓦片的编号，边界经纬度等信息
for (int j = Convert.ToInt32(range.Min.Y); j <= Convert.ToInt32(range.Max.Y); j++)
{
for (int i = Convert.ToInt32(range.Min.X); i <= Convert.ToInt32(range.Max.X); i++)
{
//反算每块瓦片的边界经纬度
List <Coordinate> coordinates = new List <Coordinate>();
coordinates.Add(Projection.PointToLatLng(new Coordinate(i * 256, j * 256), zoom));
coordinates.Add(Projection.PointToLatLng(new Coordinate(i * 256 + 256, j * 256 + 256), zoom));
//
GTileElement tile = new GTileElement()
{
X = i,
Y = j,
Z = zoom,
Bound = new GBound(coordinates)
};
TileDictionary[zoom].Add(tile);
}
}
}
/// <summary>
/// 构造函数
/// example var layer = new WebMercatorGridLayer(）
/// </summary>
/// <param name="bound"></param>
public VectorPyramid(GBound bound = null)
{
if (bound == null)
{
bound = new GBound(new List <Coordinate>()
{
new Coordinate(-180, 90), new Coordinate(180, -90)
});
}
for (int i = 0; i <= 19; i++)
{
Build(bound, i);
}
}
/// <summary>
/// 给当前坐标编码
/// </summary>
/// <param name="x"></param>
/// <param name="y"></param>
/// <param name="bound"></param>
/// <returns></returns>
private static byte Encode(double x, double y, GBound bound)
{
double xl = bound.Left, xr = bound.Right, yt = bound.Top, yb = bound.Bottom;
byte c = 0;
if (x < xl)
{
c |= LEFT;
}
if (x > xr)
{
c |= RIGHT;
}
if (y < yb)
{
c |= BOTTOM;
}
if (y > yt)
{
c |= TOP;
}
return(c);
}
/// <summary>
/// 裁剪线段
/// </summary>
/// <param name="start"></param>
/// <param name="end"></param>
/// <param name="bound"></param>
/// <returns></returns>
private static List <Coordinate> ClipLine(Coordinate start, Coordinate end, GBound bound)
{
double xl = bound.Left,
xr = bound.Right,
yt = bound.Top,
yb = bound.Bottom;
//
List <Coordinate> coords = new List <Coordinate>();
double x1 = start.X, y1 = start.Y, x2 = end.X, y2 = end.Y;
byte code1 = Encode(x1, y1, bound);
byte code2 = Encode(x2, y2, bound);
byte code;
double x = 0, y = 0;
while (code1 != 0 || code2 != 0)
{
//1.线在窗口外,返回一个空数组
if ((code1 & code2) != 0)
{
return(coords);
}
code = code1;
//找窗口外的点
if (code1 == 0)
{
code = code2;
}
//点在左边
if ((LEFT & code) != 0)
{
x = xl;
y = y1 + (y2 - y1) * (xl - x1) / (x2 - x1);
}
//点在右边
else if ((RIGHT & code) != 0)
{
x = xr;
y = y1 + (y2 - y1) * (xr - x1) / (x2 - x1);
}
//点在下面
else if ((BOTTOM & code) != 0)
{
y = yb;
x = x1 + (x2 - x1) * (yb - y1) / (y2 - y1);
}
else if ((TOP & code) != 0)
{
y = yt;
x = x1 + (x2 - x1) * (yt - y1) / (y2 - y1);
}
//
if (code == code1)
{
x1 = x;
y1 = y;
code1 = Encode(x, y, bound);
}
else
{
x2 = x;
y2 = y;
code2 = Encode(x, y, bound);
}
}
//
coords.Add(new Coordinate(x1, y1));
coords.Add(new Coordinate(x2, y2));
return(coords);
}
/// <summary>
/// 裁剪线
/// </summary>
/// <param name="subjectPolyline"></param>
/// <param name="bound"></param>
/// <returns></returns>
public static List <Coordinate> GetIntersectedPolyline(Coordinate[] subjectPolyline, GBound bound)
{
List <Coordinate> clipLines = new List <Coordinate>();
for (int i = 0; i < subjectPolyline.Length - 1; i++)
{
Coordinate p0 = subjectPolyline[i];
Coordinate p1 = subjectPolyline[i + 1];
List <Coordinate> cliped = ClipLine(p0, p1, bound);
clipLines.AddRange(cliped);
}
return(clipLines);
}
public static List <Coordinate> GetIntersectedPolygon(Coordinate[] subjectPoly, GBound bound)
{
Coordinate[] clipPoly = bound.ToClipPolygon();
if (subjectPoly.Length < 3)
{
throw new ArgumentException(string.Format("The polygons passed in must have at least 3 points: subject={0}", subjectPoly.Length.ToString()));
}
List <Coordinate> outputList = subjectPoly.ToList();
// Make sure it's clockwise
if (!IsClockwise(subjectPoly))
{
outputList.Reverse();
}
// Walk around the clip polygon clockwise
foreach (Edge clipEdge in IterateEdgesClockwise(clipPoly))
{
List <Coordinate> inputList = outputList.ToList(); // clone it
outputList.Clear();
if (inputList.Count == 0)
{
// Sometimes when the polygons don't intersect, this list goes to zero. Jump out to avoid an index out of range exception
break;
}
Coordinate S = inputList[inputList.Count - 1];
foreach (Coordinate E in inputList)
{
if (IsInside(clipEdge, E))
{
if (!IsInside(clipEdge, S))
{
Coordinate point = GetIntersect(S, E, clipEdge.From, clipEdge.To);
outputList.Add(point);
}
outputList.Add(E);
}
else if (IsInside(clipEdge, S))
{
Coordinate point = GetIntersect(S, E, clipEdge.From, clipEdge.To);
outputList.Add(point);
}
S = E;
}
}
// Exit Function
return(outputList);
}
