RealityKit/SIMD multiply a 4x4 matrix by a 3-vector

simd_matrix4x4+VectorMultiply.swift

//
//  simd_matrix4x4+VectorMultiply.swift
//
//  Created by Drew Olbrich on 1/3/24.
//  Copyright © 2024 Lunar Skydiving LLC. All rights reserved.
//
//  MIT License
//  
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//  
//  The above copyright notice and this permission notice shall be included in all
//  copies or substantial portions of the Software.
//  
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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//  SOFTWARE.
//

import simd

extension simd_float4x4 {
    
    /// Pre-multiplies a 3-vector by a 4x4 matrix.
    static func * (matrix: simd_float4x4, vector: SIMD3<Float>) -> SIMD3<Float> {
        let result = matrix*SIMD4<Float>(vector, 1)
        return SIMD3<Float>(result.x, result.y, result.z)
    }
    
}