code: public Matrix4 setToRotation (float angle, float x, float y, float z) {
          float c = FloatMath.cos(angle), s = FloatMath.sin(angle), omc = 1f - c;
          float xs = x*s, ys = y*s, zs = z*s, xy = x*y, xz = x*z, yz = y*z;
          return set(x*x*omc + c, xy*omc - zs, xz*omc + ys, 0f,
                     xy*omc + zs, y*y*omc + c, yz*omc - xs, 0f,
                     xz*omc - ys, yz*omc + xs, z*z*omc + c, 0f,
                     0f, 0f, 0f, 1f);
      }
docs: Sets this to a rotation matrix. The formula comes from the OpenGL documentation for the
  glRotatef function.
  
  @return a reference to this matrix, for chaining.