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#include <assert.h>
#include <stdbool.h>
#include <stdlib.h>
#include "../include/body.h"
typedef struct node{
int x;
int y;
struct node *next;
} NODE;
typedef struct snake{
NODE *head; //"head" will be the physical tail of the snake
NODE *tail; //"tail" will be the physical head of the snake
int length;
} SNAKE;
//private prototypes
NODE *makeNode(int x, int y);
void deleteNode(NODE *np);
void increaseSnake(SNAKE *sp);
//public functions
SNAKE *makeSnake(int startx, int starty, int len){
SNAKE *new = malloc(sizeof(SNAKE));
NODE *np;
assert(new != NULL);
new->length = len;
new->head = makeNode(startx-len+1, starty);
np = new->head;
len--;
while(len > 0){
np->next = makeNode(startx-len+1, starty);
np = np->next;
len--;
}
new->tail = np;
return new;
}
void deleteSnake(SNAKE *sp){
NODE *hold;
if(sp != NULL){
while(sp->head != NULL){
hold = sp->head;
sp->head = sp->head->next;
deleteNode(hold);
}
}
free(sp);
return;
}
void updateSnake(SNAKE *sp, int dir, int maxx, int maxy, bool *collision, int *fruit_loc, bool *fruit, int *score){
NODE *np;
if(sp == NULL) return;
//move the "back" to the "front" (note that sp->tail will not be set until after np->x and np->y are set)
np = sp->head;
sp->head = sp->head->next;
sp->tail->next = np;
np->next = NULL;
//dir decides direction the snake is moving
switch(dir){
case(0): //snake is moving up
np->x = sp->tail->x;
np->y = sp->tail->y-1;
break;
case(1): //snake is moving right
np->x = sp->tail->x+1;
np->y = sp->tail->y;
break;
case(2): //snake is moving down
np->x = sp->tail->x;
np->y = sp->tail->y+1;
break;
case(3): //snake is moving left
np->x = sp->tail->x-1;
np->y = sp->tail->y;
}
//update tail pointer
sp->tail = np;
//check if eating fruit
if(*fruit && sp->tail->x == *fruit_loc && sp->tail->y == *(fruit_loc + 1)){
*fruit = false;
(*score)++;
//need to increase snake size
increaseSnake(sp);
}
//check collision
*collision = checkSnake(sp, maxx, maxy);
return;
}
//true = collision, false = no collision
bool checkSnake(SNAKE *sp, int maxx, int maxy){
NODE *np;
if(sp == NULL) return true;
//check if oob
if(sp->tail->x < 0 || sp->tail->x >= maxx || sp->tail->y < 0 || sp->tail->y >= maxy) return true;
//check if collision with body (check each cell)
np = sp->head;
while(np != sp->tail && np != NULL){
if(sp->tail->x == np->x && sp->tail->y == np->y) return true;
np = np->next;
}
return false;
}
int getSnakeTailx(SNAKE *sp){
if(sp != NULL && sp->tail != NULL) return sp->tail->x;
return -1;
}
int getSnakeTaily(SNAKE *sp){
if(sp != NULL && sp->tail != NULL) return sp->tail->y;
return -1;
}
int getSnakeHeadx(SNAKE *sp){
if(sp != NULL && sp->head != NULL) return sp->head->x;
return -1;
}
int getSnakeHeady(SNAKE *sp){
if(sp != NULL && sp->head != NULL) return sp->head->y;
return -1;
}
//private functions
NODE *makeNode(int x, int y){
NODE *new = malloc(sizeof(NODE));
assert(new != NULL);
new->x = x;
new->y = y;
new->next = NULL;
return new;
}
void deleteNode(NODE *np){
if(np != NULL) free(np);
return;
}
void increaseSnake(SNAKE *sp){
int xdiff = sp->head->next->x - sp->head->x;
int ydiff = sp->head->next->y - sp->head->y;
NODE *new = makeNode(sp->head->x - xdiff, sp->head->y - ydiff);
new->next = sp->head;
sp->head = new;
sp->length++;
return;
}
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