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Sutherland-Hodgman polygon clipping: Difference between revisions
Sutherland-Hodgman polygon clipping (view source)
Revision as of 13:49, 20 February 2020
, 4 years agoAdd Swift
SqrtNegInf (talk | contribs) (Added Perl example) |
(Add Swift) |
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Line 3,120:
(100.00, 250.00)
</pre>
=={{header|Swift}}==
{{trans|Rust}}
<lang swift>struct Point {
var x: Double
var y: Double
}
struct Polygon {
var points: [Point]
init(points: [Point]) {
self.points = points
}
init(points: [(Double, Double)]) {
self.init(points: points.map({ Point(x: $0.0, y: $0.1) }))
}
}
func isInside(_ p1: Point, _ p2: Point, _ p3: Point) -> Bool {
(p3.x - p2.x) * (p1.y - p2.y) > (p3.y - p2.y) * (p1.x - p2.x)
}
func computeIntersection(_ p1: Point, _ p2: Point, _ s: Point, _ e: Point) -> Point {
let dc = Point(x: p1.x - p2.x, y: p1.y - p2.y)
let dp = Point(x: s.x - e.x, y: s.y - e.y)
let n1 = p1.x * p2.y - p1.y * p2.x
let n2 = s.x * e.y - s.y * e.x
let n3 = 1.0 / (dc.x * dp.y - dc.y * dp.x)
return Point(x: (n1 * dp.x - n2 * dc.x) * n3, y: (n1 * dp.y - n2 * dc.y) * n3)
}
func sutherlandHodgmanClip(subjPoly: Polygon, clipPoly: Polygon) -> Polygon {
var ring = subjPoly.points
var p1 = clipPoly.points.last!
for p2 in clipPoly.points {
let input = ring
var s = input.last!
ring = []
for e in input {
if isInside(e, p1, p2) {
if !isInside(s, p1, p2) {
ring.append(computeIntersection(p1, p2, s, e))
}
ring.append(e)
} else if isInside(s, p1, p2) {
ring.append(computeIntersection(p1, p2, s, e))
}
s = e
}
p1 = p2
}
return Polygon(points: ring)
}
let subj = Polygon(points: [
(50.0, 150.0),
(200.0, 50.0),
(350.0, 150.0),
(350.0, 300.0),
(250.0, 300.0),
(200.0, 250.0),
(150.0, 350.0),
(100.0, 250.0),
(100.0, 200.0)
])
let clip = Polygon(points: [
(100.0, 100.0),
(300.0, 100.0),
(300.0, 300.0),
(100.0, 300.0)
])
print(sutherlandHodgmanClip(subjPoly: subj, clipPoly: clip))</lang>
{{out}}
<pre>Polygon(points: [Point(x: 100.0, y: 116.66666666666667), Point(x: 125.00000000000001, y: 100.0), Point(x: 275.0, y: 100.0), Point(x: 300.0, y: 116.66666666666667), Point(x: 300.0, y: 299.99999999999994), Point(x: 250.0, y: 300.0), Point(x: 200.0, y: 250.0), Point(x: 175.0, y: 300.0), Point(x: 125.0, y: 300.0), Point(x: 100.0, y: 250.0)])</pre>
=={{header|Tcl}}==
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