Created
March 11, 2022 07:53
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| const slope = getSlope(firstPoint, secondPoint); | |
| const perpSlope = getPerpSlope(slope); | |
| let perpPointOne = findPointOnLine(firstPoint, perpSlope, 10); | |
| let perpPointTwo = findPointOnLine(firstPoint, perpSlope, -10); | |
| ctx.moveTo(perpPointOne.x, perpPointOne.y); | |
| ctx.lineTo(perpPointTwo.x, perpPointTwo.y); | |
| perpPointOne = findPointOnLine(secondPoint, perpSlope, 10); | |
| perpPointTwo = findPointOnLine(secondPoint, perpSlope, -10); | |
| ctx.moveTo(perpPointOne.x, perpPointOne.y); | |
| ctx.lineTo(perpPointTwo.x, perpPointTwo.y); | |
| ctx.stroke(); | |
| function getSlope(pointA, pointB) | |
| { | |
| return (pointB.y - pointA.y) / (pointB.x - pointA.x); | |
| } | |
| function getPerpSlope(slope) | |
| { | |
| return -1 / slope; | |
| } | |
| function findPointOnLine(startPoint, slope, distance) | |
| { | |
| const newPoint = { }; | |
| if (slope === 0) { | |
| newPoint.x = startPoint.x + distance; | |
| newPoint.y = startPoint.y; | |
| } else if (slope === Infinity) { | |
| newPoint.x = startPoint.x; | |
| newPoint.y = startPoint.y + distance; | |
| } else { | |
| dx = (distance / Math.sqrt(1 + (slope * slope))); | |
| dy = slope * dx; | |
| newPoint.x = startPoint.x + dx; | |
| newPoint.y = startPoint.y + dy; | |
| } | |
| return newPoint; | |
| } |
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