ludic/docs/language/screen/screen-show.md

id	name	category	kind	tokens	sig	tip	order	ns	member
screen-show	Screen.show	screen	namespace-method	Screen.show	Screen.show()	Present the finished frame — copy everything drawn this frame to the window.	6	Screen	show

Presents the frame: it copies everything you have drawn into the framebuffer this pass onto the visible window all at once. Call it exactly once, as the very last statement of your Render handler, after every Screen.clear, fill_rectangle, draw_text, and other draw call. Because drawing happens off-screen and only show makes it visible, the player never sees a half-drawn frame (no flicker or tearing). Forgetting to call it means your drawing never appears; it takes no arguments.

program PresentFrame {
  property Position { column: int = 0, row: int = 0 }
  model Player { Position }

  const TILE_SIZE: int = 16

  handler SpawnPlayer phase Start {
    spawn Player { Position { column: 5, row: 5 } }
  }

  handler DrawWorld phase Render {
    Screen.clear(Color.MidnightBlue)
    for (Position) in query [Position, {Player}] {
      Screen.fill_rectangle(
        x: Position.column * TILE_SIZE,
        y: Position.row * TILE_SIZE,
        width: TILE_SIZE,
        height: TILE_SIZE,
        color: Color.LimeGreen)
    }
    Screen.show()
  }
}