/*
See LICENSE folder for this sample’s licensing information.

Abstract:
Convenience extensions for system types.
*/

import ARKit
import SceneKit

extension SCNMatrix4 {
    /**
     Create a 4x4 matrix from CGAffineTransform, which represents a 3x3 matrix
     but stores only the 6 elements needed for 2D affine transformations.
     
     [ a  b  0 ]     [ a  b  0  0 ]
     [ c  d  0 ]  -> [ c  d  0  0 ]
     [ tx ty 1 ]     [ 0  0  1  0 ]
     .               [ tx ty 0  1 ]
     
     Used for transforming texture coordinates in the shader modifier.
     (Needs to be SCNMatrix4, not SIMD float4x4, for passing to shader modifier via KVC.)
     */
    init(_ affineTransform: CGAffineTransform) {
        self.init()
        m11 = Float(affineTransform.a)
        m12 = Float(affineTransform.b)
        m21 = Float(affineTransform.c)
        m22 = Float(affineTransform.d)
        m41 = Float(affineTransform.tx)
        m42 = Float(affineTransform.ty)
        m33 = 1
        m44 = 1
    }
}

extension SCNReferenceNode {
    convenience init(named resourceName: String, loadImmediately: Bool = true) {
        let url = Bundle.main.url(forResource: resourceName, withExtension: "scn", subdirectory: "Models.scnassets")!
        self.init(url: url)!
        if loadImmediately {
            self.load()
        }
    }
}