# Tetris (C + SDL3)

A small Tetris clone written in C using SDL3 for rendering/input and SDL3_ttf for text.

## Build

Requirements:
- CMake (3.7+)
- SDL3
- A C compiler (gcc/clang)

Configure and build:

```bash
cmake -S . -B build
cmake --build build
```

Run:

```bash
./build/tetris
```

## Controls

- Move left: `Left` or `A`
- Move right: `Right` or `D`
- Rotate: `Up` or `W`
- Soft drop: `Down` or `S`
- Quit: `Q` or `Esc`

## Gameplay Notes

- The board is `10 x 16` (`include/grid.h`).
- Shapes are stored as an origin block plus 3 relative offsets (`src/shape.c`).
- Rotation uses a 90-degree transform around the origin: `(x, y) -> (-y, x)` (`src/game.c`).
- Collision checks allow negative `y` values so pieces can spawn/rotate partly above the visible top (`src/grid.c`).
- Line clear logic re-checks the same row index after a clear, because rows above are shifted down (`src/grid.c`).

## Debug Logging

Debug logs are compiled in when `APP_DEBUG` is enabled (for example in Debug builds through CMake).