Add examples catalog with subcommand dispatch

- Extract game engine from package main to engine/ library package
- Create examples/ package with registry, Entry type, and BuilderDeps
- Register default world as an example (moved from main())
- Add combat example: two teams of units facing each other
- Rewrite main.go as thin dispatch: go run . example [name]
- Update README with examples catalog one-liner

1 files changed, 36 insertions, 0 deletions

diff --git a/engine/input.go b/engine/input.go
new file mode 100644
index 0000000..5d03b08
--- /dev/null
+++ b/engine/input.go
@@ -0,0 +1,36 @@
+package engine
+
+import (
+	"age_of_empires/physics"
+
+	"github.com/hajimehoshi/ebiten/v2"
+	"github.com/hajimehoshi/ebiten/v2/inpututil"
+)
+
+type Input struct {
+	Cursor       physics.Point
+	ScreenCursor physics.Point
+
+	EscapePressed bool
+	PatrolPressed bool
+
+	LeftMouseDown bool
+	LeftMouseUp   bool
+	RightMouseUp  bool
+
+	SpawnPressed bool
+}
+
+func CollectInput(camera *Camera) Input {
+	sx, sy := ebiten.CursorPosition()
+	return Input{
+		Cursor:        camera.ScreenToWorld(sx, sy),
+		ScreenCursor:  physics.Point{X: sx, Y: sy},
+		EscapePressed: inpututil.IsKeyJustReleased(ebiten.KeyEscape),
+		PatrolPressed: inpututil.IsKeyJustReleased(KeyPatrolRequest),
+		LeftMouseDown: inpututil.IsMouseButtonJustPressed(ebiten.MouseButtonLeft),
+		LeftMouseUp:   inpututil.IsMouseButtonJustReleased(ebiten.MouseButtonLeft),
+		RightMouseUp:  inpututil.IsMouseButtonJustReleased(ebiten.MouseButtonRight),
+		SpawnPressed:  inpututil.IsKeyJustReleased(KeySpawnRequest),
+	}
+}