OpenGL4.x不支持gluPerspective函数。故备份之

template <typename type>
inline mat4<type> mat4<type>::perspectiveProjection(type fovy, type aspect, type zNear, type zFar)
{
    type f = (type)  / tan(radians(fovy) / );
    return mat4<type>(f / aspect, , ,                         ,
                      ,        f, ,                         ,
                      ,        , (zFar + zNear) / (zNear - zFar), (*zFar*zNear) / (zNear - zFar),
                      ,        , -,                        );
}

template <typename type>
inline mat4<type> mat4<type>::orthoProjection(type xRight, type xLeft, type yTop, type yBottom, type zNear, type zFar)
{
    type tx, ty, tz;
    tx = - (xRight + xLeft) / (xRight - xLeft);
    ty = - (yTop + yBottom) / (yTop - yBottom);
    tz = - (zFar + zNear) / (zFar - zNear);
    return mat4<type>( / (xRight - xLeft), ,                  ,                tx,
                       ,                   / (yTop - yBottom), ,                ty,
                       ,                  ,                 - / (zFar - zNear), tz,
                       ,                  ,                  ,                );
}