SDL2 Lessons

What SDL Is SDL, the Simple DirectMedia Layer, is a low-level multimedia library used to create windows, capture input. This course takes you from opening a window to structuring. SDL core for initialization, windows, rendering, timing, and input SDL

game/
  src/
    main.cpp
    app.cpp
    player.cpp
  include/
  assets/
    textures/
    audio/
    fonts/
  CMakeLists.txt

Create the Window A stable loop is the backbone of every SDL application. The design goal is not just. Poll all queued events Measure frame delta time SDL_Window* window = SDL_CreateWindow( "CodeByte SDL", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTER

SDL_Window* window = SDL_CreateWindow(
    "CodeByte SDL",
    SDL_WINDOWPOS_CENTERED,
    SDL_WINDOWPOS_CENTERED,
    1280, 720,
    SDL_WINDOW_SHOWN
);

Event Polling Instead of hard-coding gameplay directly to keys, map raw input to named actions such as move_left. Event-based input for one-time actions like pause, jump, menu. State-based input via SDL_GetKeyboardState for continuous movement SDL_Ev

SDL_Event event;
while (SDL_PollEvent(&event)) {
    if (event.type == SDL_QUIT) running = false;
    if (event.type == SDL_KEYDOWN && event.key.keysym.sym == SDLK_ESCAPE)
        running = false;
}

Surfaces vs Textures SDL often loads image data into a surface first, then converts it into a GPU-friendly texture. Load once, reuse many times Store textures in a resource manager SDL_Surface* surface = IMG_Load("assets/textures/player.png"); SDL_Te

SDL_Surface* surface = IMG_Load("assets/textures/player.png");
SDL_Texture* playerTexture = SDL_CreateTextureFromSurface(renderer, surface);
SDL_FreeSurface(surface);

Why Delta Time Matters If one computer renders 144 frames per second and another renders 30, movement must still feel. Animation often advances through frames based on a timer, not. Movement and camera follow Cooldowns and invulnerability windows flo

float delta = currentTime - previousTime;
player.x += player.velocityX * delta;
player.y += player.velocityY * delta;

Axis-Aligned Bounding Boxes In 2D games, the camera is often just an offset. You keep world positions in game. World space for gameplay logic Screen space for final drawing and UI SDL_Rect player{px, py, 32, 48}; SDL_Rect wall{wx, wy, 64, 64}; if (SD

SDL_Rect player{px, py, 32, 48};
SDL_Rect wall{wx, wy, 64, 64};
if (SDL_HasIntersection(&player, &wall)) {
    // resolve collision
}

Audio Layers Treat menus like a separate state with its own input rules, focus handling, and rendering flow. Short sound effects for feedback Looping music for mood and pacing TTF_Font* font = TTF_OpenFont("assets/fonts/jetbrains.ttf", 24); SDL_Surfa

TTF_Font* font = TTF_OpenFont("assets/fonts/jetbrains.ttf", 24);
SDL_Surface* textSurface = TTF_RenderText_Blended(font, "Score: 1250", color);
SDL_Texture* textTexture = SDL_CreateTextureFromSurface(renderer, textSurface);

Core Systems Small prototypes tolerate messy code. Complete games do not. Clean boundaries let you change levels, UI. Push platform details such as SDL window calls to the. App: owns initialization and shutdown State manager: menu, gameplay, pause, g

// State manager simulation
const states = ["boot", "menu", "gameplay", "pause", "gameover"];
let current = states[1];
console.log("current state:", current);
current = "gameplay";
console.log("switch to:", current);
const resources = { textures:3, fonts:1, sounds:5 };
console.log("resource summary:", resources);

Debugging Checklist Finish the course by building a complete 2D action prototype with menus, sprites, sound, collisions, camera. Validate every SDL call that can fail Log file paths and renderer capabilities

// Release checklist
const checklist = [
  "error handling",
  "asset manifest",
  "fixed controls",
  "volume settings",
  "performance pass",
  "export package"
];
checklist.forEach(item => console.log("[ ] " + item));
console.log("Capstone: top-down dungeon prototype");