ludic/examples/library/sprite_render.ludic

# sprite_render.ludic — the engine-owned sprite-render system (#85). Declare a
# Sprite component (from ludic.core) on an entity with a Position and the engine
# draws it each Render frame — no hand-written Render handler querying positions
# and calling draw_sprite per entity. A `hidden` sprite is skipped. Verified by
# pixel readback after one frame.
#
# Driven headless by one stdin key ('q' quits after the frame renders).
#   printf 'q' | LUDIC_MODULES=packages bin/ludic examples/library/sprite_render.ludic  ->  1 0
program SpriteRender {
  import "ludic.core/components.ludic"

  state SpriteRenderState {
    HERO: int = 0
  }

  @OnStart handler Boot(sprite_render_st: mut SpriteRenderState) {
    sprite_render_st.HERO = png_load("assets/kenney/tiny-dungeon/Tiles/tile_0096.png")
    spawn Shown  { Position { x: 40, y: 40 },  Sprite { id: sprite_render_st.HERO } }
    spawn Hidden { Position { x: 100, y: 40 }, Sprite { id: sprite_render_st.HERO, hidden: 1 } }
  }

  # An empty Render handler: the engine sprite system draws the Sprite entities.
  handler Draw phase Render { }

  @OnQuit handler Report {
    var drew = 0
    for yy in 40 .. 56 { for xx in 40 .. 56 { if Screen.pixel(xx, yy) != 0 { drew = 1 } } }
    print(drew)                          # 1 — the engine drew the shown sprite

    var hid = 0
    for yy in 40 .. 56 { for xx in 100 .. 116 { if Screen.pixel(xx, yy) != 0 { hid = 1 } } }
    print(hid)                           # 0 — the hidden sprite was skipped
  }
}