float frustum_w = frustum_h*aspect;
float left = frustum_w*(frustum_x-1.0f);
float right = frustum_w*(frustum_x+1.0f);
float bottom = frustum_h*(frustum_y-1.0f);
float top = frustum_h*(frustum_y+1.0f);
float frustum_w = frustum_h*aspect;
float left = frustum_w*(frustum_x-1.0f);
float right = frustum_w*(frustum_x+1.0f);
float bottom = frustum_h*(frustum_y-1.0f);
float top = frustum_h*(frustum_y+1.0f);