# smooth.ludic — a synthetic 2 km test ground for the terrain renderer.
#
# The valley scene stands on a real survey (Copernicus GLO-30 resampled to a 4 m grid),
# which carries its own resampling lattice and quantisation. This scene carries none:
# the height field is an analytic function (see SMOOTH in heightgen.frag), so anything
# that still looks like a grid here belongs to the renderer, not the data.
#
#   bin/ludic build examples/rendering/smooth.ludic && ./build/smooth
program Smooth {
  numbers float
  import "ludic.render3d/r3d.ludic"

  property Marker { on: int = 1 }
  model Anchor { Marker }

  var frame: int = 0
  var shot_at: int = 40
  var walk: bool = false
  var spin: bool = false
  var l_blades: Layer = null
  var l_grass_a: Layer = null
  var l_grass_b: Layer = null
  var s_blades: Stream = null
  var s_cards_a: Stream = null
  var s_cards_b: Stream = null
  var l_trees: Layer = null

  function rnd() -> float { return float(rng_range(0, 9999)) / 10000.0 }
  function rnd_range(a: float, b: float) -> float { return Math.lerp(a, b, rnd()) }
  function smooth(a: float, b: float, x: float) -> float {
    let t = Math.clamp((x - a) / (b - a), 0.0, 1.0)
    return t * t * (3.0 - 2.0 * t)
  }
  function slope_at(x: float, z: float) -> float {
    let e = 2.0
    let dx = terrain_height(x + e, z) - terrain_height(x - e, z)
    let dz = terrain_height(x, z + e) - terrain_height(x, z - e)
    let ny = 4.0 / Math.sqrt(dx * dx + dz * dz + 16.0)
    return 1.0 - ny
  }
  function noise01(x: float, z: float, scale: fixed) -> float {
    let n = Noise.fbm2(fixed(x) * scale, fixed(z) * scale, 0, 4)
    return float(n * 0.5 + 0.5)
  }

  # grass only where the ground is grassy: gentle, above the water, below the mountain
  function stream_fill(s: Stream, cx: int, cz: int, band: int) -> void {
    seed((cx * 73856093) ^ (cz * 19349663) ^ (band * 83492791) ^ (s.kind * 2654435761))
    let size = s.size
    let x0 = float(cx) * size;  let z0 = float(cz) * size
    # Candidate spacing. These are metres between attempts, so halving one quadruples the
    # work and the instance count: the first pass here was dense enough to bury the scene
    # and cost most of the frame. Blades are only placed close to the eye, where they read
    # as individual grass; past that the cards carry the cover.
    var step = 1.0
    if s.kind == 0 { if band == 0 { step = 0.22 } else if band == 1 { step = 0.45 } else { step = 1.1 } }
    else { if band == 0 { step = 0.9 } else if band == 1 { step = 1.8 } else { step = 4.0 } }
    var z = z0
    while z < z0 + size {
      var x = x0
      while x < x0 + size {
        let px = x + rnd() * step
        let pz = z + rnd() * step
        let h = terrain_height(px, pz)
        # Grassy ground only: above the water, off the steep parts, below the rim. Every
        # test is a smooth ramp — a hard height cut carves the cover into contour rings,
        # because the cut lands on a line of constant elevation.
        var keep = smooth(0.2, 1.6, h)                       # out of the water
        keep = keep * smooth(90.0, 45.0, h)                # below the mountain
        keep = keep * smooth(0.42, 0.16, slope_at(px, pz))
        keep = keep * (0.25 + 0.9 * noise01(px, pz, 0.02))
        keep = keep * 0.75
        var sc = rnd_range(0.16, 0.4)
        if s.kind != 0 { sc = rnd_range(1.5, 2.5) * (1.0 + 0.5 * float(band)) }
        if rnd() < keep {
          stream_emit(s, px, h - 0.03, pz, sc, rnd() * (2.0 * PI), rnd(), rnd_range(0.6, 1.0))
        }
        x = x + step
      }
      z = z + step
    }
  }

  function scene_draw() -> void { scatter_draw() }
  function scene_draw_casters(light_vp: floats) -> void { scatter_draw_casters(light_vp) }

  handler Boot phase Start {
    spawn Anchor {}
    r3d_on_draw(fn scene_draw)
    r3d_on_casters(fn scene_draw_casters)
    r3d_on_stream_fill(fn stream_fill)
    # 2 km square, generated analytically
    TERRAIN_HALF = 1000
    ter_smooth = true
    if not r3d_init(1920, 1080, "Smooth") {
      quit()
      return
    }
    walk = Os.has_env("R3D_WALK")
    spin = Os.has_env("R3D_SPIN")
    if Os.has_env("R3D_SHOT") { shot_at = Text.to_int(Os.env("R3D_SHOT")) }

    var cx = 0.0;  var cz = 260.0
    if Os.has_env("R3D_CAM_X") { cx = float(Text.to_int(Os.env("R3D_CAM_X"))) }
    if Os.has_env("R3D_CAM_Z") { cz = float(Text.to_int(Os.env("R3D_CAM_Z"))) }
    var ch = 1.8;  var cp = -3.0;  var cy = 180.0
    if Os.has_env("R3D_CAM_H") { ch = float(Text.to_int(Os.env("R3D_CAM_H"))) }
    if Os.has_env("R3D_CAM_PITCH") { cp = float(Text.to_int(Os.env("R3D_CAM_PITCH"))) }
    if Os.has_env("R3D_CAM_YAW") { cy = float(Text.to_int(Os.env("R3D_CAM_YAW"))) }
    cam_set(cx, terrain_height(cx, cz) + ch, cz, cy, cp)

    # a small pond in the middle of the meadow — the plane self-clips to the basin, so
    # its extent only has to cover the hollow, not the map
    water_init(4.0, 0.0, 0.0, 200.0, 200.0)
    sky_set_yaw(Math.deg_to_rad(120.0))

    # grass: blades underfoot, cards beyond
    let dir = r3d_assets + "/models/grass_medium_01"
    let ga = gltf_load(dir, "grass_medium_01_1k.gltf", "grass_medium_01_tall_a_LOD0")
    let gb = gltf_load(dir, "grass_medium_01_1k.gltf", "grass_medium_01_mid_a_LOD0")
    if ga == null or gb == null { print("smooth: no grass models");  return }
    # blades are the expensive layer: keep them near, and cap them low
    l_blades = layer_new(model_blade(), 400000, true, 3.0, 0.0, 70.0)
    l_blades.blade = true
    l_grass_a = layer_cards(ga, 200000, 0.3, 260.0)
    l_grass_b = layer_cards(gb, 200000, 0.3, 260.0)
    v3_set(l_grass_a.tint, 0.95, 1.0, 0.85)
    v3_set(l_grass_b.tint, 0.9, 0.98, 0.8)
    l_grass_a.rough = 1.6;  l_grass_b.rough = 1.6
    s_blades = stream_new(l_blades, 8.0, 60.0, 12.0, 28.0, 60.0, 60.0)
    s_cards_a = stream_new(l_grass_a, 32.0, 240.0, 45.0, 110.0, 240.0, 240.0)
    s_cards_b = stream_new(l_grass_b, 32.0, 240.0, 45.0, 110.0, 240.0, 240.0)
    s_blades.kind = 0;  s_cards_a.kind = 1;  s_cards_b.kind = 2
    place_trees()
  }

  # scattered firs on the gentle ground, thinning toward the pond and the rim
  function place_trees() -> void {
    let model = gltf_load(r3d_assets + "/models/fir_tree_01", "fir_tree_01_1k.gltf", "fir_tree_01_c_LOD0")
    if model == null { print("smooth: no fir model");  return }
    l_trees = layer_new(model, 20000, false, 0.0, 90.0, 0.0)
    layer_set_impostor(l_trees, impostor_bake(model, 12, 512, 1024))
    v3_set(l_trees.tint, 0.9, 1.0, 0.85)
    seed(4242)
    var z = -900.0
    while z < 900.0 {
      var x = -900.0
      while x < 900.0 {
        let px = x + rnd() * 14.0;  let pz = z + rnd() * 14.0
        let h = terrain_height(px, pz)
        var keep = smooth(7.0, 14.0, h)                 # above the pond shore
        keep = keep * smooth(120.0, 60.0, h)      # below the rim
        keep = keep * smooth(0.45, 0.2, slope_at(px, pz))
        keep = keep * smooth(0.45, 0.75, noise01(px, pz, 0.004))
        if rnd() < keep * 0.5 {
          let sc = rnd_range(0.7, 1.35)
          layer_add(l_trees, px, h - 0.2, pz, sc, rnd() * (2.0 * PI), rnd(), 0.0)
        }
        x = x + 14.0
      }
      z = z + 14.0
    }
  }

  handler Fly phase Input {
    if walk { cam_move(1.0, 0.0, 0.0, 0.003, 0.0);  return }
    if spin { cam_move(0.0, 0.0, 0.0, 0.02, 0.0);  return }
    if not is_windowed() { return }
    Input.poll()
    var fwd = 0.0;  var side = 0.0;  var up = 0.0
    let speed = 0.6
    if Input.key_down(key: 'w') { fwd = speed }
    if Input.key_down(key: 's') { fwd = -speed }
    if Input.key_down(key: 'd') { side = speed }
    if Input.key_down(key: 'a') { side = -speed }
    if Input.key_down(key: 'e') { up = speed }
    if Input.key_down(key: 'q') { up = -speed }
    var dyaw = 0.0;  var dpitch = 0.0
    if Input.mouse_down(button: 0) {
      dyaw = float(Input.mouse_dx()) * -0.004
      dpitch = float(Input.mouse_dy()) * -0.004
    }
    if fwd != 0 or side != 0 or up != 0 or dyaw != 0 or dpitch != 0 { cam_move(fwd, side, up, dyaw, dpitch) }
    if Input.key_pressed(key: 'p') {
      let gy = terrain_height(cam_pos[0], cam_pos[2])
      print(`R3D_CAM_X={string(int(cam_pos[0]))} R3D_CAM_Z={string(int(cam_pos[2]))} R3D_CAM_H={string(int(cam_pos[1] - gy))} R3D_CAM_YAW={string(int(cam_yaw * (180.0 / PI)))} R3D_CAM_PITCH={string(int(cam_pitch * (180.0 / PI)))}`)
    }
  }

  handler Draw phase Render {
    r3d_frame(float(Time.elapsed()))
    frame += 1
    if frame == shot_at { Gl.screenshot(path: "build/smooth.ppm") }
    Gl.swap()
  }
}