如何通过鼠标点击获得鼠标点的三维世界坐标呢?OPENGL

void UnProject(float mouse_x,float mouse_y) //鼠标位置{double modelview[16],projection[16];int viewport[4];float winX,winY,winZ;double object_x = 0,object_y = 0,object_z = 0; //3D坐标glGetDoublev(GL_MODELVIEW_MATRIX,modelview);glGetDoublev(GL_PROJECTION_MATRIX,projection);glGetIntegerv(GL_VIEWPORT,viewport);winX=(float)mouse_x;winY=(float)viewport[3]-(float)mouse_y;glReadPixels(mouse_x,int(winY),1,1,GL_DEPTH_COMPONENT,GL_FLOAT,&winZ);gluUnProject((GLdouble)winX,(GLdouble)winY,(GLdouble)winZ,modelview,projection,viewport,&object_x,&object_y,&object_z);}