keyword
layer
layer Name { handlers }
A layer groups handlers inside a scene, and declaration order is draw order: within a phase the active scene's layers run in the order they were written, so a Hud layer declared after a World layer paints its Render output on top. Layers are the natural unit for stacking a heads-up display over the play-field, or a menu over a paused world. A layer handler may use any phase except Start (boot-time setup belongs in the scene's on enter). Handlers that should run in every scene are declared outside any scene rather than in a layer.
Example
program LayerExample {
property Position { column: int = 0, row: int = 0 }
model Player { Position }
var score: int = 0
scene Overworld start {
on enter { spawn Player { Position { column: 6, row: 6 } } }
layer World {
handler DrawWorld phase Render {
Screen.clear(Color.MidnightBlue)
for (current_position) in query [Position, {Player}] {
Screen.fill_rectangle(x: current_position.column * 16, y: current_position.row * 16, width: 16, height: 16, color: Color.LimeGreen)
}
}
}
layer Hud {
handler DrawScore phase Render {
Screen.draw_text(x: 6, y: 4, text: "SCORE", color: Color.White, scale: 1)
Screen.draw_number(x: 52, y: 4, value: score, color: Color.Gold, scale: 1)
Screen.show() # the last layer to draw presents the frame
}
}
}
}