使用lua判断点在多边形内部
NWAO发表于 2015-09-19 04:01:00
1 --获取多边形外围矩形
2 function GetPolyOutRect(p, poly)
3 local l_max_x = poly[1].X;
4 local l_max_y = poly[1].Y;
5 local l_min_x = l_max_x;
6 local l_min_y = l_min_y;
7 for i = 2, #poly do
8 if l_max_x < poly[i].x then
9 l_max_x = poly[i].x;
10 end
11 if l_max_y < poly[i].y then
12 l_max_y = poly[i].y;
13 end
14 if l_min_x > poly[i].y then
15 l_min_x = poly[i].y;
16 end
17 if l_min_y > poly[i].y then
18 l_min_y = poly[i].y;
19 end
20 end
21 return {l_min_x,l_max_x,l_min_y,l_max_y};
22 end
23
24 --点是否在多边形外围矩形中
25 function IsPtInPolyRect(p, poly)
26 local rect = GetPolyOutRect(p, poly);
27 if p.x < rect[1] or p.x > rect[2] or p.y < rect[3] or p.y > rect[4] then
28 return false;
29 else
30 return true;
31 end
32 end
33
34 --判断点在多边形内true or false,点正好在多边形边上时返回值不定
35 function IsPtInPoly(p, poly)
36 if false == IsPtInPolyRect(p, poly) then
37 return false;
38 end
39 local l_odd = false;
40 local j = #poly;
41 for i = 1, #poly do
42 if ((poly[i].y < p.y and poly[j].y >= p.y) or poly[j].y < p.y and poly[i].y >= p.y)) and (poly[i].x <= p.x and poly[j].x <= p.x) then
43 if poly[i].x + (p.y - poly[i].y)*(poly[j].x - poly[i].x) / (poly[j].y - poly[i].y) < p.x then
44 l_odd = not l_odd;
45 end
46 end
47 end
48 return l_odd;
49 end
50
51 local p = {x = 2, y = 2.5};
52 local poly = {{x = 1, y = 2},{x = 2, y = 3},{x = 3, y = 2}}
53 local result = IsPtInPoly(p, poly);
54 print(result);
55 --由于无法从代码中直接复制，纯手敲代码，若有疏漏，请留言。
56 --代码参考了网上众多前辈的教程，不一一列出，感谢前辈
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2 function GetPolyOutRect(p, poly)
3 local l_max_x = poly[1].X;
4 local l_max_y = poly[1].Y;
5 local l_min_x = l_max_x;
6 local l_min_y = l_min_y;
7 for i = 2, #poly do
8 if l_max_x < poly[i].x then
9 l_max_x = poly[i].x;
10 end
11 if l_max_y < poly[i].y then
12 l_max_y = poly[i].y;
13 end
14 if l_min_x > poly[i].y then
15 l_min_x = poly[i].y;
16 end
17 if l_min_y > poly[i].y then
18 l_min_y = poly[i].y;
19 end
20 end
21 return {l_min_x,l_max_x,l_min_y,l_max_y};
22 end
23
24 --点是否在多边形外围矩形中
25 function IsPtInPolyRect(p, poly)
26 local rect = GetPolyOutRect(p, poly);
27 if p.x < rect[1] or p.x > rect[2] or p.y < rect[3] or p.y > rect[4] then
28 return false;
29 else
30 return true;
31 end
32 end
33
34 --判断点在多边形内true or false,点正好在多边形边上时返回值不定
35 function IsPtInPoly(p, poly)
36 if false == IsPtInPolyRect(p, poly) then
37 return false;
38 end
39 local l_odd = false;
40 local j = #poly;
41 for i = 1, #poly do
42 if ((poly[i].y < p.y and poly[j].y >= p.y) or poly[j].y < p.y and poly[i].y >= p.y)) and (poly[i].x <= p.x and poly[j].x <= p.x) then
43 if poly[i].x + (p.y - poly[i].y)*(poly[j].x - poly[i].x) / (poly[j].y - poly[i].y) < p.x then
44 l_odd = not l_odd;
45 end
46 end
47 end
48 return l_odd;
49 end
50
51 local p = {x = 2, y = 2.5};
52 local poly = {{x = 1, y = 2},{x = 2, y = 3},{x = 3, y = 2}}
53 local result = IsPtInPoly(p, poly);
54 print(result);
55 --由于无法从代码中直接复制，纯手敲代码，若有疏漏，请留言。
56 --代码参考了网上众多前辈的教程，不一一列出，感谢前辈
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58
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