49 lines
1.1 KiB
Kotlin
49 lines
1.1 KiB
Kotlin
package net.shadowfacts.cacao.geometry
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import java.lang.RuntimeException
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import kotlin.math.pow
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/**
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* Helper class that represents a cubic bezier curve.
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*
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* @author shadowfacts
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*/
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data class BezierCurve(private val points: Array<Point>) {
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init {
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if (points.size != 4) {
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throw RuntimeException("Cubic bezier curve must have exactly four points")
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}
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}
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fun point(time: Double): Point {
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val x = coordinate(time, Axis.HORIZONTAL)
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val y = coordinate(time, Axis.VERTICAL)
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return Point(x, y)
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}
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private fun coordinate(t: Double, axis: Axis): Double {
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// B(t)=(1-t)^3*p0+3(1-t)^2*t*p1+3(1-t)*t^2*p2+t^3*p3
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val p0 = points[0][axis]
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val p1 = points[1][axis]
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val p2 = points[2][axis]
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val p3 = points[3][axis]
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return ((1 - t).pow(3) * p0) + (3 * (1 - t).pow(2) * t * p1) + (3 * (1 - t) * t.pow(2) * p2) + (t.pow(3) * p3)
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}
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override fun equals(other: Any?): Boolean {
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if (this === other) return true
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if (javaClass != other?.javaClass) return false
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other as BezierCurve
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if (!points.contentEquals(other.points)) return false
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return true
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}
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override fun hashCode(): Int {
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return points.contentHashCode()
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}
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} |