// 凹みのある箱(Zバッファで隠面除去) [Box4.java] 
 public class Box4 { 
    final double L=60, L2=L/2.0, RH=40; 
    double [][] x={{0,0,L,L},   {L,L,L,L}, 
                   {0,0,0,0},   {0,L,L,0}, {0,L,L,0}, 
                   {0,0,L2,L2}, {L,L2,L2,L}}; // 凹み 
    double [][] y={{0,L,L,0},   {0,L,L,0}, 
                   {0,0,L,L},   {0,0,0,0}, {0,0,L,L}, 
                   {L,L,RH,RH}, {L,RH,RH,L}}; // 凹み 
    double [][] z={{0,0,0,0},   {0,0,L,L}, 
                   {0,L,L,0},   {0,0,L,L}, {L,L,L,L}, 
                   {0,L,L,0},   {0,0,L,L}};   // 凹み 
 }//end Box4