Vec4.js

export function create() {
    return [0, 0, 0, 1];
}

export function equals(a,b) {
    return a[0] == b[0] &&
        a[1] == b[1] &&
        a[2] == b[2] &&
        a[3] == b[3];
}

export function equals4(a,x,y,z,w){
    return a[0] == x &&
        a[1] == y &&
        a[2] == z &&
        a[3] == w;
}

export function set(a,b){
    a[0] = b[0];
    a[1] = b[1];
    a[2] = b[2];
    a[3] = b[3];
    return a;
}

export function set4(a,x,y,z,w){
    a[0] = x;
    a[1] = y;
    a[2] = z;
    a[3] = w;
    return a;
}

export function fromVec3(a,b){
    a[0] = b[0];
    a[1] = b[1];
    a[2] = b[2];
    return a;
}

export function copy(a, out){
    if(out !== undefined){
        out[0] = a[0];
        out[1] = a[1];
        out[2] = a[2];
        out[3] = a[3];
        return out;
    }
    return a.slice(0);
}

export function multMat4(a,m){
    var x = a[0];
    var y = a[1];
    var z = a[2];
    var w = a[3];
    a[0] = m[ 0] * x + m[ 4] * y + m[ 8] * z + m[12] * w;
    a[1] = m[ 1] * x + m[ 5] * y + m[ 9] * z + m[13] * w;
    a[2] = m[ 2] * x + m[ 6] * y + m[10] * z + m[14] * w;
    a[3] = m[ 3] * x + m[ 7] * y + m[11] * z + m[15] * w;
    return a;
}

export function multedMat4(a,m){
    return multMat4(copy(a),m);
}

export function lerp(a,b,n){
    var x = a[0];
    var y = a[1];
    var z = a[2];
    var w = a[3];

    a[0] = x + (b[0] - x) * n;
    a[1] = y + (b[1] - y) * n;
    a[2] = z + (b[2] - z) * n;
    a[3] = w + (b[3] - w) * n;

    return a;
}

export function lerped(a,b,n){
    return lerp(copy(a),b,n);
}