PhysicsSystem grid world (draft)

/*
Github: https://github.com/nezvers
Youtube: https://www.youtube.com/channel/UCb4-Y0E6mmwjtawcitIAzKQ
Twitter: https://twitter.com/NeZversStudio
*/

#include <stdlib.h>
#include <string.h>
#include <stdio.h>


// Physics body
typedef struct{
    int i;
}Body;

typedef struct{
    int count;
    Body *list;
}Cell;

typedef struct{
    int width;
    int height;
    Cell *cell;
}GridMap;

void init_GridMap(GridMap *grid){
    grid->cell = (Cell*)calloc(grid->width *grid->height, sizeof(Cell));
}


Cell* get_cell(GridMap *grid, int x, int y){
    return &grid->cell[x + y*grid->width];
}

void add_body_to_cell(Cell *cell, Body *body, int x, int y){
    cell->count++;
    printf("%d \n", cell->count);
    Body *old = cell->list;
    cell->list = (Body*)calloc(cell->count, sizeof(Body));
    memcpy(cell->list, old, sizeof(Body)*(cell->count -1));
    Body *p = cell->list + cell->count;
    p = body;
    free(old);
}

void add_body_to_grid(GridMap *grid, Body *body, int x, int y){
    Cell *cell = get_cell(grid, x, y);
    add_body_to_cell(cell, body, x, y);
}

void remove_body_from_cell(Cell *cell, Body *body, int x, int y){
    cell->count--;
    Body *old = cell->list;
    cell->list = (Body*)calloc(cell->count, sizeof(Body));
    int j = 0;
    for(int i=0; i < cell->count; i++){
        if(&old[i] != body){
            cell->list[j] = old[i];
            j++;
        }
    }
    free(old);
}

void remove_body_from_grid(GridMap *grid, Body *body, int x, int y){
    Cell *cell = get_cell(grid, x, y);
    remove_body_from_cell(cell, body, x, y);
}

void destroy_GridMap(GridMap *grid){
    for(int y = 0; y<grid->height; y++){
        for(int x=0; x<grid->width; x++){
            Cell *cell = get_cell(grid, x, y);
            if(cell != NULL){
                free(cell->list);
            }
        }
    }
    free(grid->cell);
}




int main(){
    GridMap grid = {0};
    grid.width = 100;
    grid.height = 100;
    init_GridMap(&grid);

    Body body = {0};
    add_body_to_grid(&grid, &body, 25, 40);
    Cell *cell = get_cell(&grid, 25, 40);
    cell->list[0].i = 54;

    printf("body now: %d \n", cell->list[0].i);

    destroy_GridMap(&grid);
    return 0;
}