pub fn view_matrix(position: &[f32; 3], direction: &[f32; 3], up: &[f32; 3]) -> [[f32; 4]; 4] {
    let f = {
        let f = direction;
        let len = f[0] * f[0] + f[1] * f[1] + f[2] * f[2];
        let len = len.sqrt();
        [f[0] / len, f[1] / len, f[2] / len]
    };

    let s = [up[1] * f[2] - up[2] * f[1],
             up[2] * f[0] - up[0] * f[2],
             up[0] * f[1] - up[1] * f[0]];

    let s_norm = {
        let len = s[0] * s[0] + s[1] * s[1] + s[2] * s[2];
        let len = len.sqrt();
        [s[0] / len, s[1] / len, s[2] / len]
    };

    let u = [f[1] * s_norm[2] - f[2] * s_norm[1],
             f[2] * s_norm[0] - f[0] * s_norm[2],
             f[0] * s_norm[1] - f[1] * s_norm[0]];

    let p = [-position[0] * s_norm[0] - position[1] * s_norm[1] - position[2] * s_norm[2],
             -position[0] * u[0] - position[1] * u[1] - position[2] * u[2],
             -position[0] * f[0] - position[1] * f[1] - position[2] * f[2]];

    [
        [s[0], u[0], f[0], 0.0],
        [s[1], u[1], f[1], 0.0],
        [s[2], u[2], f[2], 0.0],
        [p[0], p[1], p[2], 1.0],
    ]
}
/// Returns a column-major view matrix.
Returns a column-major view matrix.
Returns a column - major view matrix .
pub fn view_matrix(position: &[f32; 3], direction: &[f32; 3], up: &[f32; 3]) -> [[f32; 4]; 4] {
    let f = {
        let f = direction;
        let len = f[0] * f[0] + f[1] * f[1] + f[2] * f[2];
        let len = len.sqrt();
        [f[0] / len, f[1] / len, f[2] / len]
    };
    let s = [up[1] * f[2] - up[2] * f[1],
             up[2] * f[0] - up[0] * f[2],
             up[0] * f[1] - up[1] * f[0]];
    let s_norm = {
        let len = s[0] * s[0] + s[1] * s[1] + s[2] * s[2];
        let len = len.sqrt();
        [s[0] / len, s[1] / len, s[2] / len]
    };
    let u = [f[1] * s_norm[2] - f[2] * s_norm[1],
             f[2] * s_norm[0] - f[0] * s_norm[2],
             f[0] * s_norm[1] - f[1] * s_norm[0]];
    let p = [-position[0] * s_norm[0] - position[1] * s_norm[1] - position[2] * s_norm[2],
             -position[0] * u[0] - position[1] * u[1] - position[2] * u[2],
             -position[0] * f[0] - position[1] * f[1] - position[2] * f[2]];
    [
        [s[0], u[0], f[0], 0.0],
        [s[1], u[1], f[1], 0.0],
        [s[2], u[2], f[2], 0.0],
        [p[0], p[1], p[2], 1.0],
    ]
}
pub fn view_matrix ( position : & [ f32 ; 3 ] , direction : & [ f32 ; 3 ] , up : & [ f32 ; 3 ] ) -> [ [ f32 ; 4 ] ; 4 ] { let f = { let f = direction ; let len = f [ 0 ] * f [ 0 ] + f [ 1 ] * f [ 1 ] + f [ 2 ] * f [ 2 ] ; let len = len . sqrt ( ) ; [ f [ 0 ] / len , f [ 1 ] / len , f [ 2 ] / len ] } ; let s = [ up [ 1 ] * f [ 2 ] - up [ 2 ] * f [ 1 ] , up [ 2 ] * f [ 0 ] - up [ 0 ] * f [ 2 ] , up [ 0 ] * f [ 1 ] - up [ 1 ] * f [ 0 ] ] ; let s_norm = { let len = s [ 0 ] * s [ 0 ] + s [ 1 ] * s [ 1 ] + s [ 2 ] * s [ 2 ] ; let len = len . sqrt ( ) ; [ s [ 0 ] / len , s [ 1 ] / len , s [ 2 ] / len ] } ; let u = [ f [ 1 ] * s_norm [ 2 ] - f [ 2 ] * s_norm [ 1 ] , f [ 2 ] * s_norm [ 0 ] - f [ 0 ] * s_norm [ 2 ] , f [ 0 ] * s_norm [ 1 ] - f [ 1 ] * s_norm [ 0 ] ] ; let p = [ - position [ 0 ] * s_norm [ 0 ] - position [ 1 ] * s_norm [ 1 ] - position [ 2 ] * s_norm [ 2 ] , - position [ 0 ] * u [ 0 ] - position [ 1 ] * u [ 1 ] - position [ 2 ] * u [ 2 ] , - position [ 0 ] * f [ 0 ] - position [ 1 ] * f [ 1 ] - position [ 2 ] * f [ 2 ] ] ; [ [ s [ 0 ] , u [ 0 ] , f [ 0 ] , 0.0 ] , [ s [ 1 ] , u [ 1 ] , f [ 1 ] , 0.0 ] , [ s [ 2 ] , u [ 2 ] , f [ 2 ] , 0.0 ] , [ p [ 0 ] , p [ 1 ] , p [ 2 ] , 1.0 ] , ] }
Returns a column-major view matrix.
Returns a column - major view matrix .
position
&[f32; 3]
direction
&[f32; 3]
up
&[f32; 3]
position
&[f32; 3]
direction
&[f32; 3]
up
&[f32; 3]