//
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// CGVectorExtensions.swift
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// SwifterSwift
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//
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// Created by Robbie Moyer on 7/25/18.
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// Copyright © 2018 SwifterSwift
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//
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#if canImport(CoreGraphics)
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import CoreGraphics
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// MARK: - Properties
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public extension CGVector {
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/// SwifterSwift: The angle of rotation (in radians) of the vector. The range of the angle is -π to π; an angle of 0 points to the right.
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///
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/// https://en.wikipedia.org/wiki/Atan2
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var angle: CGFloat {
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return atan2(dy, dx)
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}
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/// SwifterSwift: The magnitude (or length) of the vector.
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///
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/// https://en.wikipedia.org/wiki/Euclidean_vector#Length
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var magnitude: CGFloat {
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return sqrt((dx * dx) + (dy * dy))
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}
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}
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// MARK: - Initializers
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public extension CGVector {
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/// SwifterSwift: Creates a vector with the given magnitude and angle.
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///
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/// let vector = CGVector(angle: .pi, magnitude: 1)
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///
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/// - Parameters:
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/// - angle: The angle of rotation (in radians) counterclockwise from the positive x-axis.
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/// - magnitude: The lenth of the vector.
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///
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init(angle: CGFloat, magnitude: CGFloat) {
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// https://www.grc.nasa.gov/WWW/K-12/airplane/vectpart.html
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self.init(dx: magnitude * cos(angle), dy: magnitude * sin(angle))
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}
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}
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// MARK: - Operators
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public extension CGVector {
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/// SwifterSwift: Multiplies a scalar and a vector (commutative).
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///
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/// let vector = CGVector(dx: 1, dy: 1)
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/// let largerVector = vector * 2
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///
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/// - Parameters:
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/// - vector: The vector to be multiplied
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/// - scalar: The scale by which the vector will be multiplied
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/// - Returns: The vector with its magnitude scaled
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static func * (vector: CGVector, scalar: CGFloat) -> CGVector {
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return CGVector(dx: vector.dx * scalar, dy: vector.dy * scalar)
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}
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/// SwifterSwift: Multiplies a scalar and a vector (commutative).
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///
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/// let vector = CGVector(dx: 1, dy: 1)
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/// let largerVector = 2 * vector
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///
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/// - Parameters:
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/// - scalar: The scalar by which the vector will be multiplied
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/// - vector: The vector to be multiplied
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/// - Returns: The vector with its magnitude scaled
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static func * (scalar: CGFloat, vector: CGVector) -> CGVector {
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return CGVector(dx: scalar * vector.dx, dy: scalar * vector.dy)
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}
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/// SwifterSwift: Compound assignment operator for vector-scalr multiplication
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///
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/// var vector = CGVector(dx: 1, dy: 1)
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/// vector *= 2
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///
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/// - Parameters:
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/// - vector: The vector to be multiplied
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/// - scalar: The scale by which the vector will be multiplied
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static func *= (vector: inout CGVector, scalar: CGFloat) {
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// swiftlint:disable:next shorthand_operator
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vector = vector * scalar
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}
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/// SwifterSwift: Negates the vector. The direction is reversed, but magnitude remains the same.
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///
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/// let vector = CGVector(dx: 1, dy: 1)
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/// let reversedVector = -vector
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///
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/// - Parameter vector: The vector to be negated
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/// - Returns: The negated vector
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static prefix func - (vector: CGVector) -> CGVector {
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return CGVector(dx: -vector.dx, dy: -vector.dy)
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}
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}
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#endif
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