# Build one room

A level has a manifest, world geometry, and its own textures. Create
`levels/room/`, add a tileable `surface.png`, and save this as `level.toml`:

```toml
[level]
name = "levels.room"
kind = "world"

[world]
source = "world.yaml"

[[textures]]
name = "surface"
source = "surface.png"
profile = "environment"
```

Save this as `world.yaml`. X/Y describe the floor plan; Z is height. These
coordinates make an eight-metre square room with a three-metre ceiling.

```yaml
version: 19
rooms:
  - id: room
    rect: {width: 8, depth: 8, material: surface}
    floor: {c: 0}
    ceiling: {c: 3}
    floor_material: surface
    ceiling_material: surface
```

The build expands `rect` into four counterclockwise edges named `south`, `east`,
`north` and `west`. Use those names for connections. For an irregular room or
individual wall settings, use an explicit `boundary` instead of `rect`.
Run `karty schema` for editor suggestions, or `karty schema --check` to check
the world before processing assets.

Replace `src/main.go` with this room viewer. Change the import if your project
has a different name. The camera starts at `(2, 2, 1.7)`; the text shows loading
errors above the scene. The CLI generates `assets.LevelRoom` from the manifest's logical
name; the callback supplied to `LoadLevel` receives only that load's ready result.

```go
package main

import (
	"example.com/my-game/.karty/assets"
	"example.com/my-game/.karty/engine"
)

type Game struct {
	engine.Game
	camera *engine.Camera3D
	label  *engine.Text2D
}

//go:wasmexport karty_register
func main() {
	game := &Game{}
	engine.Run(engine.Hooks{
		OnStart: func() {
			game.label = game.NewText2D("Loading room...", engine.NewVec2(24, 24))
			game.LoadLevel(assets.LevelRoom, func(event engine.LevelReady) {
				game.camera = game.NewCamera3D(event.Handle, engine.Camera3DSettings{
					Projection: engine.CameraProjectionPerspective, Output: engine.CameraOutputFull,
					Position: engine.NewVec3(2, 2, 1.7), VerticalFOV: 1.05,
					NearClip: 0.05, FarClip: 100, OrthoHeight: 10,
					ViewportWidth: 960, ViewportHeight: 540,
				})
				game.camera.SetLayer(-1)
				game.label.SetText("")
			})
		},
		OnLevelFailed: func(event engine.LevelFailed) {
			game.label.SetText(event.Diagnostic)
		},
	})
}
```

Run `karty dev` to view the room. Match the viewport to your `karty.toml`
resolution if you change it. This camera stays still. Add [first-person
controls](fps.html) to walk around, or an [isometric camera](isometric.html) to
view the room from above.

![Hangar connects industrial rooms with open passages.](assets/hangar.jpg)

Add a second room only after you can explore the first. A connection names an
edge in each room and opens a portal between them; see Hangar
for complete connections, including a non-Euclidean portal loop.