error shape when get part render

[zhangzhenyu-zzy]

when i want to training straps,i find a problem,i put the vertices and cam_t in renderer,can not get the true shape ,the shape is not (B,N,W,H)，just a image(3,256,256),your code wirte that parts, _, mask = self.renderer(vertices, self.faces, self.textures, t=cam_ts),but i can not get three value,just one value which shape is 3,256,256