ludic/examples/snake.ludic

# ============================================================================
# snake.ludic — a second, unrelated game in Ludic, to prove the language is
# general: compiled by the SAME unmodified ludicc + runtime as the JRPG.
# No sprites/assets — pure primitives. Build: ./build.sh examples/snake.ludic
# ============================================================================
program Snake {

  property Pos { x: int = 0, y: int = 0 }
  property Seg { order: int = 0 }

  const GW: int = 20
  const GH: int = 15
  const TS: int = 16

  const R_DIR:   int = 0    # 0 up 1 down 2 left 3 right
  const R_LEN:   int = 1
  const R_TICK:  int = 2
  const R_FX:    int = 3
  const R_FY:    int = 4
  const R_MODE:  int = 5    # 0 play 1 gameover
  const R_SCORE: int = 6
  const R_ATE:   int = 7
  const R_TX:    int = 8
  const R_TY:    int = 9
  const R_ACK:   int = 10

  fn reset(x: int) -> int {
    for (p, s) in query [Pos, Seg] { despawn self() }
    spawn S0 { Seg { order: 0 };  Pos { x: 10, y: 7 } }
    spawn S1 { Seg { order: 1 };  Pos { x: 9,  y: 7 } }
    spawn S2 { Seg { order: 2 };  Pos { x: 8,  y: 7 } }
    set_reg(R_DIR, 3)
    set_reg(R_LEN, 3)
    set_reg(R_TICK, 0)
    set_reg(R_MODE, 0)
    set_reg(R_SCORE, 0)
    set_reg(R_FX, 14)
    set_reg(R_FY, 7)
    return 0
  }

  handler Boot phase Start { reset(0) }

  handler Input phase Input {
    let k = key()
    if reg(R_MODE) == 0 {
      if k == 'w' { if reg(R_DIR) != 1 { set_reg(R_DIR, 0) } }
      if k == 's' { if reg(R_DIR) != 0 { set_reg(R_DIR, 1) } }
      if k == 'a' { if reg(R_DIR) != 3 { set_reg(R_DIR, 2) } }
      if k == 'd' { if reg(R_DIR) != 2 { set_reg(R_DIR, 3) } }
    }
    if reg(R_MODE) == 1 {
      if k == 0 { set_reg(R_ACK, 1) }
      if k != 0 { if reg(R_ACK) == 1 { reset(0) } }
    }
  }

  handler Move phase Update {
    if reg(R_MODE) == 0 {
      set_reg(R_TICK, reg(R_TICK) + 1)
      if reg(R_TICK) >= 6 {
        set_reg(R_TICK, 0)
        let len = reg(R_LEN)
        for (pt, stg) in query [Pos, Seg] {
          if stg.order == len - 1 { set_reg(R_TX, pt.x);  set_reg(R_TY, pt.y) }
        }
        for step in 0 .. len {
          let i = len - 1 - step
          if i >= 1 {
            for (pa, sa) in query [Pos, Seg] {
              if sa.order == i {
                for (pb, sb) in query [Pos, Seg] {
                  if sb.order == i - 1 { pa.x = pb.x;  pa.y = pb.y }
                }
              }
            }
          }
        }
        set_reg(R_ATE, 0)
        for (ph, sh) in query [Pos, Seg] {
          if sh.order == 0 {
            if reg(R_DIR) == 0 { ph.y = ph.y - 1 }
            if reg(R_DIR) == 1 { ph.y = ph.y + 1 }
            if reg(R_DIR) == 2 { ph.x = ph.x - 1 }
            if reg(R_DIR) == 3 { ph.x = ph.x + 1 }
            if ph.x < 0 { set_reg(R_MODE, 1) }
            if ph.x >= GW { set_reg(R_MODE, 1) }
            if ph.y < 0 { set_reg(R_MODE, 1) }
            if ph.y >= GH { set_reg(R_MODE, 1) }
            if ph.x == reg(R_FX) { if ph.y == reg(R_FY) { set_reg(R_ATE, 1) } }
          }
        }
        for (ph, sh) in query [Pos, Seg] {
          if sh.order == 0 {
            for (pb, sb) in query [Pos, Seg] {
              if sb.order > 0 {
                if pb.x == ph.x { if pb.y == ph.y { set_reg(R_MODE, 1) } }
              }
            }
          }
        }
        if reg(R_ATE) == 1 {
          set_reg(R_SCORE, reg(R_SCORE) + 1)
          spawn Body { Seg { order: len };  Pos { x: reg(R_TX), y: reg(R_TY) } }
          set_reg(R_LEN, len + 1)
          set_reg(R_FX, rng_range(0, GW - 1))
          set_reg(R_FY, rng_range(0, GH - 1))
        }
      }
    }
  }

  handler Draw phase Render {
    clear(0x0d1020)
    for gy in 0 .. GH {
      for gx in 0 .. GW {
        var col = 0x141a2e
        if (gx + gy) % 2 == 0 { col = 0x10162a }
        fill_rect(gx * TS, gy * TS, TS, TS, col)
      }
    }
    fill_rect(reg(R_FX) * TS + 3, reg(R_FY) * TS + 3, TS - 6, TS - 6, 0xe0405a)
    for (p, s) in query [Pos, Seg] {
      var col = 0x40c060
      if s.order == 0 { col = 0x9dffb0 }
      fill_rect(p.x * TS + 1, p.y * TS + 1, TS - 2, TS - 2, col)
    }
    text(6, 4, "SCORE", 0xffffff, 1)
    text_int(52, 4, reg(R_SCORE), 0xffe060, 1)
    if reg(R_MODE) == 1 {
      text(112, 104, "GAME OVER", 0xff5555, 2)
      text(84, 140, "PRESS ANY KEY", 0xffffff, 1)
    }
    present()
  }
}