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Add circle calculation
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@elcolto
elcolto committed May 9, 2024
1 parent 812654b commit d3ac535
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Showing 4 changed files with 356 additions and 1 deletion.
29 changes: 28 additions & 1 deletion turf/src/commonMain/kotlin/io/github/dellisd/spatialk/turf/Transformation.kt
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Original file line number Diff line number Diff line change
@@ -1,7 +1,10 @@
package io.github.dellisd.spatialk.turf

import io.github.dellisd.spatialk.geojson.LineString
import io.github.dellisd.spatialk.geojson.Point
import io.github.dellisd.spatialk.geojson.Polygon
import io.github.dellisd.spatialk.geojson.Position
import kotlin.jvm.JvmOverloads

/**
* Takes a [LineString] and returns a curved version by applying a Bezier spline algorithm.
Expand All @@ -14,7 +17,7 @@ import io.github.dellisd.spatialk.geojson.Position
* @param sharpness a measure of how curvy the path should be between splines
* @return A [LineString] containing a curved line around the positions of the input line
*/
@OptIn(ExperimentalTurfApi::class)
@ExperimentalTurfApi
public fun bezierSpline(line: LineString, duration: Int = 10_000, sharpness: Double = 0.85): LineString =
LineString(bezierSpline(line.coordAll(), duration, sharpness))

Expand Down Expand Up @@ -134,3 +137,27 @@ public fun bezierSpline(coords: List<Position>, duration: Int = 10_000, sharpnes

return positions
}

/**
* Takes a [Point] and calculates the circle polygon given a radius in degrees, radians, miles, or kilometers; and steps
* for precision.
*
* @param center center point of circle
* @param radius radius of the circle defined in [units]
* @param steps number of steps, must be at least four. Default is 64
* @param units unit of [radius], default is [Units.Kilometers]
*/
@JvmOverloads
@ExperimentalTurfApi
public fun circle(center: Point, radius: Double, steps: Int = 64, units: Units = Units.Kilometers): Polygon {
require(steps >= 4) { "circle needs to have four or more coordinates." }
require(radius > 0) { "radius must be a positive value" }
val coordinates = (0..steps).map { step ->
destination(center.coordinates, radius, ((step * -360) / steps.toDouble()), units)
}
val ring = coordinates.plus(coordinates.first())
return Polygon(
coordinates = listOf(ring),
bbox = computeBbox(ring)
)
}
19 changes: 19 additions & 0 deletions turf/src/commonTest/kotlin/io/github/dellisd/spatialk/turf/TransformationTest.kt
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Original file line number Diff line number Diff line change
@@ -1,8 +1,12 @@
package io.github.dellisd.spatialk.turf

import io.github.dellisd.spatialk.geojson.Feature
import io.github.dellisd.spatialk.geojson.FeatureCollection
import io.github.dellisd.spatialk.geojson.LineString
import io.github.dellisd.spatialk.geojson.Point
import io.github.dellisd.spatialk.turf.utils.readResource
import kotlinx.serialization.json.double
import kotlinx.serialization.json.jsonPrimitive
import kotlin.test.Test
import kotlin.test.assertEquals

Expand Down Expand Up @@ -37,4 +41,19 @@ class TransformationTest {

assertEquals(expectedOut.geometry, bezierSpline(feature.geometry as LineString))
}

@Test
fun testCircle() {
val point = Feature.fromJson(readResource("transformation/circle/in/circle1.json"))
val expectedOut = FeatureCollection.fromJson(readResource("transformation/circle/out/circle1.json"))

val (_, expectedCircle) = expectedOut.features

val circle = circle(
center = point.geometry as Point,
radius = point.properties["radius"]?.jsonPrimitive?.double ?: 0.0,
)

assertEquals(expectedCircle.geometry, circle)
}
}
10 changes: 10 additions & 0 deletions turf/src/commonTest/resources/transformation/circle/in/circle1.json
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Original file line number Diff line number Diff line change
@@ -0,0 +1,10 @@
{
"type": "Feature",
"properties": {
"radius": 5
},
"geometry": {
"type": "Point",
"coordinates": [-75.343, 39.984]
}
}
299 changes: 299 additions & 0 deletions turf/src/commonTest/resources/transformation/circle/out/circle1.json
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Original file line number Diff line number Diff line change
@@ -0,0 +1,299 @@
{
"type": "FeatureCollection",
"features": [
{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [
-75.343,
39.984
]
},
"properties": {
"radius": 5
}
},
{
"type": "Feature",
"geometry": {
"type": "Polygon",
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39.93903398181377,
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40.02896601818623
],
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},
"properties": {}
}
]
}

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