56 lines
2.9 KiB
JavaScript
56 lines
2.9 KiB
JavaScript
export const POLYGON = 'polygon'
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export const DIRECTION_LINE = 'direction_line'
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export function clamp(value) {
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return Math.min(1, Math.max(0, Number(value)))
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}
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export function geometryError(kind, points, direction = '') {
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if (!Array.isArray(points)) return '请在画面中添加坐标点'
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if (kind === POLYGON && (points.length < 3 || points.length > 64)) return '多边形需要 3 到 64 个点'
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if (kind === DIRECTION_LINE && points.length !== 2) return '方向警戒线需要恰好 2 个点'
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if (kind === DIRECTION_LINE && !['forward', 'reverse'].includes(direction)) return '请选择警戒方向'
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if (![POLYGON, DIRECTION_LINE].includes(kind)) return '请选择配置类型'
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if (points.some(point => !Number.isFinite(point.x) || !Number.isFinite(point.y) || point.x < 0 || point.x > 1 || point.y < 0 || point.y > 1)) return '坐标必须位于画面范围内'
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if (kind === POLYGON && selfIntersects(points)) return '多边形边线不能交叉，请调整顶点'
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if (kind === POLYGON && Math.abs(polygonArea(points)) < 0.000001) return '多边形面积过小，请重新绘制'
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if (kind === DIRECTION_LINE && samePoint(points[0], points[1])) return '警戒线起点和终点不能重合'
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return ''
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}
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function samePoint(a, b) {
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return Math.abs(a.x - b.x) < 0.0000001 && Math.abs(a.y - b.y) < 0.0000001
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}
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function polygonArea(points) {
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return points.reduce((total, point, index) => {
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const next = points[(index + 1) % points.length]
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return total + point.x * next.y - next.x * point.y
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}, 0) / 2
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}
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function selfIntersects(points) {
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for (let first = 0; first < points.length; first += 1) {
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const a = points[first]
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const b = points[(first + 1) % points.length]
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for (let second = first + 1; second < points.length; second += 1) {
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if (second === first || second === (first + 1) % points.length || first === (second + 1) % points.length) continue
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const c = points[second]
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const d = points[(second + 1) % points.length]
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if (segmentsIntersect(a, b, c, d)) return true
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}
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}
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return false
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}
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function segmentsIntersect(a, b, c, d) {
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const orientation = (p, q, r) => (q.y - p.y) * (r.x - q.x) - (q.x - p.x) * (r.y - q.y)
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const values = [orientation(a, b, c), orientation(a, b, d), orientation(c, d, a), orientation(c, d, b)]
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if (((values[0] > 0 && values[1] < 0) || (values[0] < 0 && values[1] > 0)) && ((values[2] > 0 && values[3] < 0) || (values[2] < 0 && values[3] > 0))) return true
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const onSegment = (p, q, r) => q.x <= Math.max(p.x, r.x) + 0.0000001 && q.x >= Math.min(p.x, r.x) - 0.0000001 && q.y <= Math.max(p.y, r.y) + 0.0000001 && q.y >= Math.min(p.y, r.y) - 0.0000001
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return (Math.abs(values[0]) < 0.0000001 && onSegment(a, c, b)) ||
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(Math.abs(values[1]) < 0.0000001 && onSegment(a, d, b)) ||
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(Math.abs(values[2]) < 0.0000001 && onSegment(c, a, d)) ||
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(Math.abs(values[3]) < 0.0000001 && onSegment(c, b, d))
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}
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