Line circle intersection: Difference between revisions
Added Swift solution
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(Added Swift solution) |
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points on the line are: (0,-3) and (0,6) are: 0,4
The line is secant to circle with radius: 4
</pre>
=={{header|Swift}}==
{{trans|Java}}
<lang swift>import Foundation
import CoreGraphics
func lineCircleIntersection(start: NSPoint, end: NSPoint, center: NSPoint,
radius: CGFloat, segment: Bool) -> [NSPoint] {
var result: [NSPoint] = []
let angle = atan2(end.y - start.y, end.x - start.x)
var at = AffineTransform(rotationByRadians: angle)
at.invert()
at.translate(x: -center.x, y: -center.y)
let p1 = at.transform(start)
let p2 = at.transform(end)
let minX = min(p1.x, p2.x), maxX = max(p1.x, p2.x)
let y = p1.y
at.invert()
func addPoint(x: CGFloat, y: CGFloat) {
if !segment || (x <= maxX && x >= minX) {
result.append(at.transform(NSMakePoint(x, y)))
}
}
if y == radius || y == -radius {
addPoint(x: 0, y: y)
} else if y < radius && y > -radius {
let x = (radius * radius - y * y).squareRoot()
addPoint(x: -x, y: y)
addPoint(x: x, y: y)
}
return result
}
func toString(points: [NSPoint]) -> String {
var result = "["
result += points.map{String(format: "(%.4f, %.4f)", $0.x, $0.y)}.joined(separator: ", ")
result += "]"
return result
}
var center = NSMakePoint(3, -5)
var radius: CGFloat = 3
print("The intersection points (if any) between:")
print("\n A circle, center (3, -5) with radius 3, and:")
print("\n a line containing the points (-10, 11) and (10, -9) is/are:")
var points = lineCircleIntersection(start: NSMakePoint(-10, 11), end: NSMakePoint(10, -9),
center: center, radius: radius,
segment: false)
print(" \(toString(points: points))")
print("\n a segment starting at (-10, 11) and ending at (-11, 12) is/are")
points = lineCircleIntersection(start: NSMakePoint(-10, 11), end: NSMakePoint(-11, 12),
center: center, radius: radius,
segment: true)
print(" \(toString(points: points))")
print("\n a horizontal line containing the points (3, -2) and (7, -2) is/are:")
points = lineCircleIntersection(start: NSMakePoint(3, -2), end: NSMakePoint(7, -2),
center: center, radius: radius,
segment: false)
print(" \(toString(points: points))")
center.x = 0
center.y = 0
radius = 4
print("\n A circle, center (0, 0) with radius 4, and:")
print("\n a vertical line containing the points (0, -3) and (0, 6) is/are:")
points = lineCircleIntersection(start: NSMakePoint(0, -3), end: NSMakePoint(0, 6),
center: center, radius: radius,
segment: false)
print(" \(toString(points: points))")
print("\n a vertical segment starting at (0, -3) and ending at (0, 6) is/are:")
points = lineCircleIntersection(start: NSMakePoint(0, -3), end: NSMakePoint(0, 6),
center: center, radius: radius,
segment: true)
print(" \(toString(points: points))")
center.x = 4
center.y = 2
radius = 5
print("\n A circle, center (4, 2) with radius 5, and:")
print("\n a line containing the points (6, 3) and (10, 7) is/are:")
points = lineCircleIntersection(start: NSMakePoint(6, 3), end: NSMakePoint(10, 7),
center: center, radius: radius,
segment: false)
print(" \(toString(points: points))")
print("\n a segment starting at (7, 4) and ending at (11, 8) is/are:")
points = lineCircleIntersection(start: NSMakePoint(7, 4), end: NSMakePoint(11, 8),
center: center, radius: radius,
segment: true)
print(" \(toString(points: points))")</lang>
{{out}}
<pre>
The intersection points (if any) between:
A circle, center (3, -5) with radius 3, and:
a line containing the points (-10, 11) and (10, -9) is/are:
[(3.0000, -2.0000), (6.0000, -5.0000)]
a segment starting at (-10, 11) and ending at (-11, 12) is/are
[]
a horizontal line containing the points (3, -2) and (7, -2) is/are:
[(3.0000, -2.0000)]
A circle, center (0, 0) with radius 4, and:
a vertical line containing the points (0, -3) and (0, 6) is/are:
[(-0.0000, -4.0000), (0.0000, 4.0000)]
a vertical segment starting at (0, -3) and ending at (0, 6) is/are:
[(0.0000, 4.0000)]
A circle, center (4, 2) with radius 5, and:
a line containing the points (6, 3) and (10, 7) is/are:
[(1.0000, -2.0000), (8.0000, 5.0000)]
a segment starting at (7, 4) and ending at (11, 8) is/are:
[(8.0000, 5.0000)]
</pre>
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