Building SDL2 from a Subdirectory (CMake)

Implementing a Basic Game Loop with SDL2

The lesson's example code uses a simple while loop for the main game loop. What does a more complete game loop look like in SDL2?

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A typical game loop in SDL2 consists of three main parts: handling events, updating the game state, and rendering the game.

Here's a basic structure:

#include <SDL.h>

const int FPS = 60;
const int DELAY_TIME = 1000.0f / FPS;

int main(int argc, char** argv) {

  SDL_Window* window{SDL_CreateWindow(
    "Game Loop Example",
    800, 600, SDL_WINDOW_SHOWN

  SDL_Renderer* renderer{SDL_CreateRenderer(
    window, -1, 0)};

  Uint32 frameStart, frameTime;

  bool quit{false};
  while (!quit) {
    frameStart = SDL_GetTicks();  

    // 1. Handle events
    SDL_Event e;
    while (SDL_PollEvent(&e)) {
      if (e.type == SDL_QUIT) {
        quit = true;

    // 2. Update game state
    // ...

    // 3. Render
      renderer, 0, 0, 0, 255);

    // Render game objects
    // ...


    frameTime = SDL_GetTicks() - frameStart;  

    if (frameTime < DELAY_TIME) {
      SDL_Delay((int)(DELAY_TIME - frameTime));  


  return 0;

This game loop:

  1. Handles events (such as user input) with SDL_PollEvent
  2. Updates the game state (e.g., positions of game objects) based on the events and game logic
  3. Renders the current game state using the SDL rendering functions

Additionally, it measures the time taken by each frame using SDL_GetTicks(), and if the frame time is less than the desired delay time (1000 / FPS), it delays the loop using SDL_Delay() to maintain a consistent frame rate.

This prevents the game from running too fast on high-performance machines and helps to decouple the game logic from the rendering speed.

Of course, this is just a basic structure, and real-world game loops can be much more complex, incorporating fixed time steps, interpolation, and other advanced techniques for smoother gameplay.

Answers to questions are automatically generated and may not have been reviewed.

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