OpenGL-like Matrix Functions in Swift

MatrixMath.swift

//
// MatrixMath.swift
// by Naomi Peori <naomi@peori.ca>
//

import Foundation

//
// Helper Functions
//

func degreesToRadians( _ degrees: Float ) -> Float
{
    return ( degrees / 180 ) * .pi
}

//
// Matrix Functions
//

func matrixFrustum( _ left: Float, _ right: Float, _ bottom: Float, _ top: Float, _ znear: Float, _ zfar: Float ) -> matrix_float4x4
{
    let A = (2.0 * znear) / (right - left)
    let B = (2.0 * znear) / (top - bottom)
    let C = (right + left) / (right - left)
    let D = (top + bottom) / (top - bottom)
    let E = (-zfar - znear) / (zfar - znear)
    let F = (-2.0 * znear * zfar) / (zfar - znear)

    return matrix_float4x4.init( columns:(
        vector_float4( A, 0, 0,  0 ),
        vector_float4( 0, B, 0,  0 ),
        vector_float4( C, D, E, -1 ),
        vector_float4( 0, 0, F,  0 )))
}

func matrixIdentity() -> matrix_float4x4
{
    return matrix_float4x4.init( columns:(
        vector_float4( 1, 0, 0, 0 ),
        vector_float4( 0, 1, 0, 0 ),
        vector_float4( 0, 0, 1, 0 ),
        vector_float4( 0, 0, 0, 1 )))
}

func matrixRotate( _ angle: Float, _ x: Float, _ y: Float, _ z: Float ) -> matrix_float4x4
{
    let radians = degreesToRadians( angle )
    let normalized = normalize( vector_float3( x, y, z ) )

    return matrixRotateX( radians * normalized[ 0 ] ) * matrixRotateY( radians * normalized[ 1 ] ) * matrixRotateZ( radians * normalized[ 2 ] );
}

func matrixRotateX( _ x: Float ) -> matrix_float4x4
{
    return matrix_float4x4.init( columns:(
        vector_float4( 1,      0,       0, 0 ),
        vector_float4( 0, cos(x), -sin(x), 0 ),
        vector_float4( 0, sin(x),  cos(x), 0 ),
        vector_float4( 0,      0,       0, 1 )))
}

func matrixRotateY( _ y: Float ) -> matrix_float4x4
{
    return matrix_float4x4.init( columns:(
        vector_float4(  cos(y), 0, sin(y), 0 ),
        vector_float4(       0, 1,      0, 0 ),
        vector_float4( -sin(y), 0, cos(y), 0 ),
        vector_float4(       0, 0,      0, 1 )))
}

func matrixRotateZ( _ z: Float ) -> matrix_float4x4
{
    return matrix_float4x4.init( columns:(
        vector_float4( cos(z), -sin(z), 0, 0 ),
        vector_float4( sin(z),  cos(z), 0, 0 ),
        vector_float4(      0,       0, 1, 0 ),
        vector_float4(      0,       0, 0, 1 )))
}

func matrixScale( _ x: Float, _ y: Float, _ z: Float ) -> matrix_float4x4
{
    return matrix_float4x4.init( columns:(
        vector_float4( x, 0, 0, 0 ),
        vector_float4( 0, y, 0, 0 ),
        vector_float4( 0, 0, z, 0 ),
        vector_float4( 0, 0, 0, 1 )))
}

func matrixTranslate( _ x: Float, _ y: Float, _ z: Float ) -> matrix_float4x4
{
    return matrix_float4x4.init( columns:(
        vector_float4( 1, 0, 0, 0 ),
        vector_float4( 0, 1, 0, 0 ),
        vector_float4( 0, 0, 1, 0 ),
        vector_float4( x, y, z, 1 )))
}

func matrixPerspective( _ fov: Float, _ aspect: Float, _ znear: Float, _ zfar: Float ) -> matrix_float4x4
{
    let ymax = znear * tan( degreesToRadians( fov ) / 2 );
    let xmax = ymax * aspect;
    
    return matrixFrustum( -xmax, xmax, -ymax, ymax, znear, zfar );
}