| export default function windingLine(x0, y0, x1, y1, x, y) { |
| if (y > y0 && y > y1 || y < y0 && y < y1) { |
| return 0; |
| } // Ignore horizontal line |
| |
| |
| if (y1 === y0) { |
| return 0; |
| } |
| |
| var dir = y1 < y0 ? 1 : -1; |
| var t = (y - y0) / (y1 - y0); // Avoid winding error when intersection point is the connect point of two line of polygon |
| |
| if (t === 1 || t === 0) { |
| dir = y1 < y0 ? 0.5 : -0.5; |
| } |
| |
| var x_ = t * (x1 - x0) + x0; // If (x, y) on the line, considered as "contain". |
| |
| return x_ === x ? Infinity : x_ > x ? dir : 0; |
| } |
