Created
December 16, 2023 14:13
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Find the perpendicular line from a line AB to point C using Turf JS
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| function slopeIx(a, b, c) { | |
| //GET POINT OF X AND Y INTERCEPT FROM POINT C AND LINE AB | |
| const lines = turf.featureCollection([]); | |
| const bearing1 = turf.bearing(a, b); | |
| const slope = (b[1] - a[1]) / (b[0] - a[0]); | |
| const point1 = [c[0], slope * (c[0] - a[0]) + a[1]]; | |
| const point2 = [(c[1] - a[1]) / slope + a[0], c[1]]; | |
| const lineArray = [a, b, point1, point2]; | |
| //NORMALIZE LINE | |
| lineArray.sort((a, b) => b[0] - a[0]); | |
| lines.features.push(turf.lineString(lineArray)); | |
| //CREATE 90DEG LINE FROM POINT C TO LINE AB | |
| const { geometry: p90 } = turf.destination( | |
| turf.point(c), | |
| //THE DISTANCE A TO C WILL ALWAYS BE LARGER THAN THE DISTANCE FROM C TO THE EXTENDED LINE AB | |
| turf.distance(a, c), | |
| bearing1 + 90 | |
| ); | |
| const { geometry: p91 } = turf.destination( | |
| turf.point(c), | |
| turf.distance(a, c), | |
| bearing1 - 90 | |
| ); | |
| const pline = turf.lineString([p90.coordinates, p91.coordinates]); | |
| lines.features.push(pline); | |
| //GET INTERSECTING POINT 90DEG FROM POINT C TO EXTENDED LINE AB | |
| const intersectingPoint = turf.lineIntersect( | |
| lines.features[0], | |
| lines.features[1] | |
| ); | |
| //GET THE DISTANCE FROM THE INTERSECTING POINT TO POINT C | |
| const distance = turf.distance(intersectingPoint.features[0], turf.point(c), { | |
| units: "miles" | |
| }); | |
| return { distance, intersectingPoint, lines } | |
| } |
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