dragonruby

# DragonRuby Game Toolkit

This skill provides comprehensive guidance for building 2D games with DragonRuby Game Toolkit (DRGTK). Use for game loop implementation, sprite rendering, input handling, collision detection, animation, and scene management.

## Quick Reference

### Basic Game Structure

```ruby
def boot args
  args.state = {}
end

def tick args
  # Called 60 times per second
  args.state.player ||= { x: 640, y: 360, w: 50, h: 50, path: 'player.png' }

  # Handle input
  args.state.player.x += 5 if args.inputs.right
  args.state.player.x -= 5 if args.inputs.left

  # Render
  args.outputs.sprites << args.state.player
end
```

### Key Concepts

| Concept | Purpose |
|---------|---------|
| `def tick(args)` | Main game loop (60 FPS) |
| `args.outputs` | Render sprites, labels, primitives |
| `args.state` | Persistent game data storage |
| `args.inputs` | Keyboard, mouse, controller input |
| `args.grid` | Screen dimensions (1280x720) |
| `Geometry` | Collision detection helpers |

### Coordinate System

- **Screen**: 1280x720 pixels
- **Origin**: Bottom-left (0, 0)
- **Y-axis**: Increases upward

```
(0, 720) ─────────────── (1280, 720)
    │                        │
    │     1280 × 720         │
    │                        │
(0, 0) ─────────────── (1280, 0)
```

## Rendering Primitives

Use `args.outputs.primitives` for FIFO (first-in, first-out) render order control.

### Sprites (Images)

```ruby
args.outputs.primitives << {
  x: 100, y: 100, w: 64, h: 64,
  path: 'sprites/player.png',
  angle: 45,
  anchor_x: 0.5, anchor_y: 0.5,
  r: 255, g: 255, b: 255, a: 255,
  flip_horizontally: false
}
```

### Labels (Text)

```ruby
args.outputs.primitives << {
  x: 640, y: 360,
  text: "Score: #{args.state.score}",
  size_px: 22,
  anchor_x: 0.5, anchor_y: 0.5,
  r: 255, g: 255, b: 255
}
```

### Solids and Borders

```ruby
# Filled rectangle (use primitive_marker: :solid)
args.outputs.primitives << {
  x: 0, y: 0, w: 100, h: 100,
  r: 255, g: 0, b: 0,
  primiti