求大神解释一下源码看不懂的四个地方，（贪吃蛇游戏）
#include<stdio.h>
#include<stdlib.h>
#include<windows.h>
#include<time.h>
#include<conio.h>
#define MOD 28 //28种模式
#define SIZE_N 19
#define SIZE_M 12
int cur_x,cur_y;
int score,mark,next,map[SIZE_N][SIZE_M],Gamespeed=300;
int shape[28][6]={//第一个问题，这些坐标什么意思啊，看不懂，能详解吗
{0,-1,0,-2,1,0}, {0,1,1,0,2,0}, {-1,0,0,1,0,2}, {0,-1,-1,0,-2,0},
{0,-1,0,1,-1,0}, {0,1,1,0,-1,0}, {1,0,0,-1,0,1}, {1,0,-1,0,0,-1},
{-1,1,0,1,1,0}, {0,-1,1,0,1,1}, {-1,0,0,-1,1,-1}, {-1,-1,-1,0,0,1},
{-1,0,0,1,1,1}, {0,1,1,-1,1,0}, {-1,0,0,1,1,1}, {0,1,1,-1,1,0},
{-1,0,0,-1,0,-2}, {-1,0,-2,0,0,1}, {0,1,0,2,1,0}, {0,-1,1,0,2,0},
{0,1,1,0,1,1}, {0,-1,1,0,1,-1}, {-1,0,0,-1,-1,-1}, {-1,0,-1,1,0,1},
{0,1,0,2,0,3}, {1,0,2,0,3,0}, {0,-1,0,-2,0,-3}, {-1,0,-2,0,-3,0}
};
void gotoxy(int x,int y){//gotoxy在TC中是在system.h库文件里的一个函
COORD c;
c.X=x-1; c.Y=y-1;
SetConsoleCursorPosition (GetStdHandle(STD_OUTPUT_HANDLE), c);
}
void Gameover()
{/*/游戏结束的判断*/
int i,j,flag=0;
for(j=1;j<SIZE_M-1;j++)
{
if(map[1][j]!=0)
{
flag=1;break;
}
}
if(flag==1)
{
for(i=1;i<SIZE_N-1;i++)
{
gotoxy(2,i+1);
for(j=1;j<SIZE_M-1;j++)
{
printf("，");
}
puts("");
}
gotoxy(7,9);
printf("GAME OVER!");
gotoxy(1,SIZE_N+1);
exit(0);
}
}
void ShowMap(int id)
{
int i,j;
gotoxy(1,1);
if(id!=-1)
{
for(i=0;i<SIZE_N;i++)
{
for(j=0;j<SIZE_M;j++)
{
if(i==0&&j==0 || i==0&&j==SIZE_M-1 || j==0&&i==SIZE_N-1 || j==SIZE_M-1&&i==SIZE_N-1)//第二个，这个又想表达什么意思？
printf(" ");
else
if(i==0 || i==SIZE_N-1)
printf("--");
else
if(j==0 || j==SIZE_M-1)
printf("|");
else
if(map[i][j]==2)
printf("，");
else
if(i==cur_x+shape[id][0] && j==cur_y+shape[id][1] ||
i==cur_x+shape[id][2] && j==cur_y+shape[id][3] ||
i==cur_x+shape[id][4] && j==cur_y+shape[id][5] ||
i==cur_x && j==cur_y)
printf("，");
else
if(map[i][j]==0)
printf(" ");
}
if(i==1)printf(" next:");
if(i==11)printf(" score : %d",score);
if(i==14)printf(" speed : %d",score/100+1);
puts("");
}
}
else {
mark=1;
for(i=0;i<SIZE_N;i++)
{
for(j=0;j<SIZE_M;j++)
{
if(i==0&&j==0 || i==0&&j==SIZE_M-1 || j==0&&i==SIZE_N-1 || j==SIZE_M-1&&i==SIZE_N-1)
printf(" ");
else
if(i==0 || i==SIZE_N-1)
printf("--");
else
if(j==0 || j==SIZE_M-1)
printf("|");
else
if(map[i][j]==2)
printf("，");
else
if(map[i][j]==0)
printf(" ");
}
if(i==1)
printf(" next:");
if(i==11)
printf(" score : %d",score);
if(i==14)
printf(" speed : %d",score/100+1);
puts("");
}
}
/*对于 next 方块的处理，先擦除再画图*/
gotoxy(30,6);
printf(" ");
for(i=0;i<6;i=i+2)
{
gotoxy(30+2*shape[id][i+1],6+shape[id][i]); //还有这个，第三个???3
printf(" ");
}
gotoxy(30,6);
printf("，");
for(i=0;i<6;i=i+2)
{
gotoxy(30+2*shape[next][i+1],6+shape[next][i]);
printf("，");
}
Sleep(Gamespeed);
}
void init(int id)
{/*/初始化函数，cur_x，cur_y是全局变量，标记了移动方块的位置*/
int i,j;
memset(map,0,sizeof(map));
for( i=0;i<SIZE_N;i++)
{
for( j=0;j<SIZE_M;j++)
if(i==SIZE_N-1 || j==0 || j==SIZE_M-1)
map[i][j]=-1;
}
cur_x=0; cur_y=5;
ShowMap(id);
}
int judge_in(int x,int y,int id){/*/判断是否出界，或者说是否合法*/
int i;
if(map[x][y]!=0)
return 0;
for( i=0;i<6;i=i+2)
{
if(map[ x+shape[id][i] ][ y+shape[id][i+1] ]!=0)
return 0;
}
return 1;
}
void fun_score()
{
/*/得分，擦除行的闪烁，还有图形的向下平移*/
int i,j,flag=0;
int k,ii,jj;
for( i=1;i<SIZE_N-1;i++)
{
flag=0;
for(j=1;j<SIZE_M-1;j++)
{
if(map[i][j]!=2)
{
flag=1;
break;
}
}
if(flag==0)
{
k=3;
while(k--)
{
gotoxy(2,i+1);
for( ii=1;ii<SIZE_M-1;ii++)
{
if(map[i][ii]==2)
{
if(k%2==1)
printf(" ");
else printf("，");
}
}
Sleep(100);
}
for( ii=i;ii>1;ii--)
{
for(jj=1;jj<SIZE_M-1;jj++)
map[ii][jj]=map[ii-1][jj];
}
ShowMap(-1);
score+=10;
if(score%100==0 && score!=0)
Gamespeed-=50;
}
}
}
int main(){
int i,id,set=1;
srand(time(NULL));
id=rand()%MOD; //id=(id+MOD)%MOD;
next=rand()%MOD; //next=(next+MOD)%MOD;
init(id);
while(1)
{
Here: mark=0;
if(set==0)
{
id=next;
next=rand()%MOD;
next=(next+MOD)%MOD;
cur_x=0;cur_y=5;
set=1;
}
while(!kbhit())
{
Gameover();
if(judge_in(cur_x+1,cur_y,id)==1)
cur_x++;
else
{
map[cur_x][cur_y]=2;
for(i=0;i<6;i=i+2)
map[ cur_x+shape[id][i] ][ cur_y+shape[id][i+1] ]=2;
fun_score();
set=0;
}
if(mark!=1)
ShowMap(id);
goto Here;
}/*/end of while(!kbhit())*/
char key;
key=getch();
if(key==72){
int tmp=id;
id++;
if( id%4==0 && id!=0 )
id=id-4;
if(judge_in(cur_x,cur_y,id)!=1)
id=tmp;
}
else if(key==80 && judge_in(cur_x+1,cur_y,id)==1)cur_x++; //第四个
else if(key==75 && judge_in(cur_x,cur_y-1,id)==1)cur_y--;
else if(key==77 && judge_in(cur_x,cur_y+1,id)==1)cur_y++;
else if(key==27){gotoxy(1,SIZE_N+1);exit(0);}
}
system("pause");
return 0;
}
