dynamis-model 0.7.0

Host facing physics descriptions, states, and derived mass properties
Documentation 
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pub fn add(a: [f32; 3], b: [f32; 3]) -> [f32; 3] {
    [a[0] + b[0], a[1] + b[1], a[2] + b[2]]
}

pub fn sub(a: [f32; 3], b: [f32; 3]) -> [f32; 3] {
    [a[0] - b[0], a[1] - b[1], a[2] - b[2]]
}

pub fn mul(v: [f32; 3], scalar: f32) -> [f32; 3] {
    [v[0] * scalar, v[1] * scalar, v[2] * scalar]
}

pub fn negate(v: [f32; 3]) -> [f32; 3] {
    [-v[0], -v[1], -v[2]]
}

pub fn dot(a: [f32; 3], b: [f32; 3]) -> f32 {
    a[0] * b[0] + a[1] * b[1] + a[2] * b[2]
}

pub fn cross(a: [f32; 3], b: [f32; 3]) -> [f32; 3] {
    [
        a[1] * b[2] - a[2] * b[1],
        a[2] * b[0] - a[0] * b[2],
        a[0] * b[1] - a[1] * b[0],
    ]
}

pub fn length(v: [f32; 3]) -> f32 {
    dot(v, v).sqrt()
}

pub fn normalize(v: [f32; 3]) -> [f32; 3] {
    mul(v, 1.0 / length(v))
}

pub fn quat_mul(a: [f32; 4], b: [f32; 4]) -> [f32; 4] {
    [
        a[3] * b[0] + a[0] * b[3] + a[1] * b[2] - a[2] * b[1],
        a[3] * b[1] + a[1] * b[3] + a[2] * b[0] - a[0] * b[2],
        a[3] * b[2] + a[2] * b[3] + a[0] * b[1] - a[1] * b[0],
        a[3] * b[3] - a[0] * b[0] - a[1] * b[1] - a[2] * b[2],
    ]
}

pub fn quat_conjugate(q: [f32; 4]) -> [f32; 4] {
    [-q[0], -q[1], -q[2], q[3]]
}

pub fn quat_rotate(q: [f32; 4], v: [f32; 3]) -> [f32; 3] {
    let u = [q[0], q[1], q[2]];
    let s = q[3];
    let dot = u[0] * v[0] + u[1] * v[1] + u[2] * v[2];
    let square = u[0] * u[0] + u[1] * u[1] + u[2] * u[2];
    let cross = [
        u[1] * v[2] - u[2] * v[1],
        u[2] * v[0] - u[0] * v[2],
        u[0] * v[1] - u[1] * v[0],
    ];
    [
        v[0] + 2.0 * (s * cross[0] + dot * u[0] - square * v[0]),
        v[1] + 2.0 * (s * cross[1] + dot * u[1] - square * v[1]),
        v[2] + 2.0 * (s * cross[2] + dot * u[2] - square * v[2]),
    ]
}