retro3d/examples/billboard_test.ce

// Billboard Test for retro3d
// Usage: cell run examples/billboard_test.ce <sprite_path>
// sprite_path should be without extension, e.g. "assets/goblin"
// Creates two rows of billboards going off into the distance like alongside a road
// Colors shift through hues as they get further away

var time_mod = use('time')
var retro3d = use('core')

var sprite_path = args[0]
if (!sprite_path) {
  log.console("Usage: cell run examples/billboard_test.ce <sprite_path>")
  log.console("  sprite_path: path without extension (e.g. 'assets/goblin')")
  $_.stop()
}

var sprite = null
var last_time = 0
var cam_angle = 0

function hsv_to_rgb(h, s, v) {
  var c = v * s
  var x = c * (1 - Math.abs((h / 60) % 2 - 1))
  var m = v - c
  
  var r = 0, g = 0, b = 0
  if (h < 60) { r = c; g = x; b = 0 }
  else if (h < 120) { r = x; g = c; b = 0 }
  else if (h < 180) { r = 0; g = c; b = x }
  else if (h < 240) { r = 0; g = x; b = c }
  else if (h < 300) { r = x; g = 0; b = c }
  else { r = c; g = 0; b = x }
  
  return [r + m, g + m, b + m, 1]
}

function _init() {
  log.console("retro3d Billboard Test")
  log.console("Loading sprite: " + sprite_path)
  
  retro3d.set_style("ps1")
  
  sprite = retro3d.load_sprite(sprite_path)
  if (!sprite) {
    log.console("Error: Could not load sprite: " + sprite_path)
    $_.stop()
    return
  }
  
  log.console("Sprite loaded: " + text(sprite.width) + "x" + text(sprite.height))
  log.console("Controls:")
  log.console("  A/D - Rotate camera")
  log.console("  ESC - Exit")
  
  retro3d.set_ambient(0.4, 0.4, 0.5)
  retro3d.set_light_dir(0.5, 1.0, 0.3, 1.0, 0.95, 0.9, 1.0)
  
  last_time = time_mod.number()
  frame()
}

function _update(dt) {
  if (retro3d._state.keys_held['escape']) {
    $_.stop()
  }
  
  if (retro3d._state.keys_held['a']) {
    cam_angle = cam_angle - 1.5 * dt
  }
  if (retro3d._state.keys_held['d']) {
    cam_angle = cam_angle + 1.5 * dt
  }
}

function _draw() {
  retro3d.clear(0.2, 0.3, 0.4, 1.0)
  
  if (!sprite) return
  
  // Set up perspective camera
  retro3d.camera_perspective(60, 0.1, 100)
  
  // Camera orbits around origin
  var cam_dist = 8
  var cam_x = Math.sin(cam_angle) * cam_dist
  var cam_z = Math.cos(cam_angle) * cam_dist
  var cam_y = 2
  
  retro3d.camera_look_at(cam_x, cam_y, cam_z, 0, 1, 0)
  
  // Draw ground plane
  retro3d.push_state()
  var ground_mat = retro3d.make_material("lit", {
    color: [0.3, 0.4, 0.3, 1]
  })
  retro3d.set_material(ground_mat)
  var ground = retro3d.make_plane(20, 20)
  var ground_transform = retro3d.make_transform()
  retro3d.draw_model(ground, ground_transform)
  retro3d.pop_state()
  
  // Draw two rows of billboards going into the distance
  // Left row at x = -2, right row at x = 2
  var num_billboards = 10
  var spacing = 2.0
  var start_z = -2
  
  for (var i = 0; i < num_billboards; i++) {
    var z = start_z - i * spacing
    var distance_norm = i / (num_billboards - 1) // 0 to 1
    
    // Hue shifts from 0 (red) to 270 (purple) as distance increases
    var hue = distance_norm * 270
    var color = hsv_to_rgb(hue, 0.9, 1.0)
    
    // Left row
    retro3d.draw_billboard(sprite, -2, 0, z, {
      color: color,
      mode: "cutout",
      face: "y"
    })
    
    // Right row (slightly different hue offset)
    var hue_right = (hue + 30) % 360
    var color_right = hsv_to_rgb(hue_right, 0.9, 1.0)
    
    retro3d.draw_billboard(sprite, 2, 0, z, {
      color: color_right,
      mode: "cutout",
      face: "y"
    })
  }
}

function frame() {
  retro3d._begin_frame()
  
  if (!retro3d._process_events()) {
    log.console("Exiting...")
    $_.stop()
    return
  }
  
  var now = time_mod.number()
  var dt = now - last_time
  last_time = now
  
  _update(dt)
  _draw()
  
  retro3d._end_frame()
  
  $_.delay(frame, 1/60)
}

_init()