Initial Commit

README.md

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+# 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).