bd028579
 易尊强
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export default function windingLine(
x0: number, y0: number, x1: number, y1: number, x: number, y: number
): number {
if ((y > y0 && y > y1) || (y < y0 && y < y1)) {
return 0;
}
// Ignore horizontal line
if (y1 === y0) {
return 0;
}
const t = (y - y0) / (y1 - y0);
let dir = y1 < y0 ? 1 : -1;
// 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;
}
const x_ = t * (x1 - x0) + x0;
// If (x, y) on the line, considered as "contain".
return x_ === x ? Infinity : x_ > x ? dir : 0;
}
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