/// <summary>
///
/// </summary>
/// <param name="v"></param>
public vec2(vec4 v)
{
this.x = v.x;
this.y = v.y;
}
/// <summary>
///
/// </summary>
/// <param name="v"></param>
public vec3(vec4 v)
{
this.x = v.x;
this.y = v.y;
this.z = v.z;
}