Windows Terminal Cube Bounce

// 2021-11-28
//
// Bounces a square around a windows terminal.
// I had a problem with flicker when trying to use system("cls") to clear the screen (I guess it's too slow?)
// But after some suggestions from some other people, and a bit of copying from stack overflow, it turns out that
// I can easily get any frame rate I could want with my current method, which is to reset the cursor to the top left
// and reprint the whole buffer. It's also possible to update on a per character basis by moving the cursor
// around to only update characters which have changed between two frames, but I like the full reprint method.

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

#define NOMINMAX
#define WIN32_LEAN_AND_MEAN
#include <Windows.h>

#define COLS 60
#define ROWS 40

#define FRAMERATE 24


int ToIndex(int x, int y){ return y * COLS + x; }

char world[COLS*ROWS] = {0};
char buffer[(COLS+1)*ROWS] = {0};

void BufferPrint(char *world);
void WorldClear(char clearCharacter);

void setCursorPosition(int x, int y);
void setCursorVisibility(int isShown);

void PaintRect(int x, int y, int w, int h, char c);

int posX = 20;
int posY = 4;
int width = 10;
int height = 6;
int velX = 1;
int velY = 1;

int main(void){
    setCursorVisibility(FALSE);
    system("cls");
    while(1){
        Sleep(1000/FRAMERATE);
        WorldClear('.');
        PaintRect(posX, posY, width, height, 'O');
        if(posX+width >= COLS-1 || posX <= 0){ velX *= -1; }
        if(posY+height >= ROWS || posY <= 0){ velY *= -1; }
        posX += velX;
        posY += velY;
        BufferPrint(world);
    }
    return 0;
}

void PaintRect(int x, int y, int w, int h, char c){
    for(int i = 0; i < h; ++i){
        for(int j = 0; j < w; ++j){
            world[ToIndex(x+j, y+i)] = c;
        }
    }
}

void WorldClear(char clearCharacter){
    for(int i = 0; i < COLS*ROWS; ++i){
        world[i] = clearCharacter;
    }
}

void BufferPrint(char *world){
    setCursorPosition(0,0);
    for(int i = 0; i < (COLS+1)*ROWS; ++i){
        buffer[i] = world[i];
        if(i % (COLS) == (COLS-1)){
            buffer[i] = '\n';
        }
    }
    buffer[COLS*ROWS] = '\0';
    fprintf(stdout, "%s", buffer);
    fflush(stdout);
    setCursorPosition(0,0);
}

void setCursorPosition(int x, int y){
    const HANDLE hOut = GetStdHandle(STD_OUTPUT_HANDLE);
    fflush(stdout);
    COORD coord = { (SHORT)x, (SHORT)y };
    SetConsoleCursorPosition(hOut, coord);
}

void setCursorVisibility(int isShown){
   HANDLE consoleHandle = GetStdHandle(STD_OUTPUT_HANDLE);
   CONSOLE_CURSOR_INFO info;
   info.dwSize = 100;
   info.bVisible = isShown;
   SetConsoleCursorInfo(consoleHandle, &info);
}