89 lines
2.8 KiB
Markdown
89 lines
2.8 KiB
Markdown
# Endless Runner
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A 2D side-scrolling endless runner built with Rust and [raylib](https://www.raylib.com/).
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## Gameplay
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Run as far as you can on procedurally generated platforms. The world scrolls faster the longer you survive. Stomp enemies for bonus points, collect power-ups, and don't fall off the screen.
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**Controls**
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| Action | Keys |
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|--------|------|
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| Jump | `Space` / `W` / `↑` |
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| Restart | `Space` / `R` / `Enter` |
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### Power-ups
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| Icon | Name | Effect |
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|------|------|--------|
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| I | **Invincible** | Immune to side hits for 5 s |
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| J | **Jump Boost** | 1.45× jump height for 6 s |
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| 2 | **2× Score** | Double score gain for 8 s |
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### Scoring
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- Passive: 80 pts/s (multiplied by any active score effect)
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- Stomp: 100 pt bonus per enemy (also multiplied)
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## Building
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**Prerequisites:** Rust toolchain, raylib system library, a Wayland compositor.
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```sh
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# debug
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cargo run
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# release (LTO + stripped)
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cargo run --release
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```
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**Tests**
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```sh
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cargo test
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```
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42 unit tests covering physics, collision, effects, and level generation.
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## Architecture
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```
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src/
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main.rs — entry point, 60 fps cap, dt capped at 0.05 s
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config.rs — Config struct (all tunable parameters)
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player.rs — vertical physics, coyote-time jump window
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platform.rs — scrolling platforms
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enemy.rs — scrolling enemies with stomp detection
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pickup.rs — PickupDef (data) + in-world Pickup instance
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effects.rs — ActiveEffect trait + three concrete impls
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level_gen.rs — procedural generation (StdRng, scrolling frontier)
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world.rs — simulation loop, collision resolution, rendering
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game.rs — state machine (Playing / GameOver), HUD
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```
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**Key design decisions**
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- Player x is fixed; only the world scrolls.
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- Speed follows `initial + factor × ln(1 + elapsed / time_scale)` — fast early ramp, logarithmic plateau.
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- Landing detection uses the previous and current bottom-y crossing the platform surface, making it tunnelling-safe at high speeds.
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- Coyote time: the jump window stays open for 120 ms after leaving a platform edge.
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- Power-ups are fully data-driven via `Config::pickup_defs`; adding a new type requires one `PickupDef` entry and one `ActiveEffect` impl.
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## Tuning
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All gameplay parameters live in `Config::default()` in `src/config.rs` — no recompilation of other modules needed when tweaking values.
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```rust
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initial_speed: 280.0, // px/s at t=0
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speed_log_factor: 150.0, // how much speed grows
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speed_time_scale: 30.0, // seconds before growth slows
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gravity: 1900.0, // px/s²
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jump_velocity: -800.0, // px/s (negative = up)
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coyote_time: 0.12, // seconds
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enemy_spawn_chance: 0.35, // per platform
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pickup_spawn_chance: 0.28, // per platform
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```
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