public Matrix4f initRotation(float x, float y, float z) {

        Matrix4f mx = new Matrix4f();
        Matrix4f my = new Matrix4f();
        Matrix4f mz = new Matrix4f();

        x = (float) Math.toRadians(x);
        y = (float) Math.toRadians(x);
        z = (float) Math.toRadians(x);

        mx.m[0][0] = (float) Math.cos(z);   mx.m[0][1] = (float) - Math.sin(z); mx.m[0][2] = 0;                     mx.m[0][3] = 0;
        mx.m[1][0] = (float) Math.sin(z);   mx.m[1][1] = (float) + Math.cos(z); mx.m[1][2] = 0;                     mx.m[1][3] = 0;
        mx.m[2][0] = 0;                     mx.m[2][1] = 0;                     mx.m[2][2] = 1;                     mx.m[2][3] = 0;
        mx.m[3][0] = 0;                     mx.m[3][1] = 0;                     mx.m[3][2] = 0;                     mx.m[3][3] = 1;

        my.m[0][0] = 1;                     my.m[0][1] = 0;                     my.m[0][2] = 0;                     my.m[0][3] = 0;
        my.m[1][0] = 0;                     my.m[1][1] = (float) Math.cos(x);   my.m[1][2] = (float) - Math.sin(x); my.m[1][3] = 0;
        my.m[2][0] = 0;                     my.m[2][1] = (float) Math.sin(x);   my.m[2][2] = (float) + Math.cos(x); my.m[2][3] = 0;
        my.m[3][0] = 0;                     my.m[3][1] = 0;                     my.m[3][2] = 0;                     my.m[3][3] = 1;

        mz.m[0][0] = (float) Math.cos(y);   mz.m[0][1] = 0;                     mz.m[0][2] = (float) - Math.sin(y); mz.m[0][3] = 0;
        mz.m[1][0] = 0;                     mz.m[1][1] = 1;                     mz.m[1][2] = 0;                     mz.m[1][3] = 0;
        mz.m[2][0] = (float) Math.sin(y);   mz.m[2][1] = 0;                     mz.m[2][2] = (float) + Math.cos(y); mz.m[2][3] = 0;
        mz.m[3][0] = 0;                     mz.m[3][1] = 0;                     mz.m[3][2] = 0;                     mz.m[3][3] = 1;

        m = mz.mul(my.mul(mx)).getM();

        return this;
    }