little birdy moves

data/scripts/game.lua

@@ -1,8 +1,14 @@
+local Vector2 = require "types.vector2"
+local player = require "player"
+
 -- called every frame, with constant delta time
 function game_tick()
   -- ctx.initialization_needed is true first frame and every time dynamic reload is performed
   if ctx.initialization_needed then
-    -- ctx.udata persists on reload
+    player:init()
     ctx.udata = {}
   end
+
+  draw_camera_2d{}
+  player:tick(ctx)
 end

data/scripts/player.lua

@@ -0,0 +1,64 @@
+local Vector2 = require "types.vector2"
+local util = require "util"
+
+local SPR = {
+  "sprites/bird1.png",
+  "sprites/bird2.png",
+}
+
+local TERMINAL_V_VEL = 25
+
+local p = {
+  position = Vector2(0, 50),
+  velocity = Vector2(),
+  size = Vector2(64, 64),
+  spr_idx = 1,
+  flip = false,
+}
+
+function p:rect()
+  return {x = self.position.x, y = self.position.y, w = self.size.x, h = self.size.y}
+end
+
+function p:init()
+  self.position.y = 50
+  self.position.x = ctx.resolution.x / 2
+end
+
+function p:is_on_ground()
+  return self.position.y >= ctx.resolution.y - 64
+end
+
+function p:tick(ctx)
+  input_action{name = "left", control = "LEFT"}
+  input_action{name = "right", control = "RIGHT"}
+
+  input_action{name = "jump", control = "SPACE"}
+
+  self.velocity.x = util.lerp(self.velocity.x, 0, 0.14)
+
+  if not self:is_on_ground() then
+    self.velocity.y = math.min(self.velocity.y + 1, TERMINAL_V_VEL)
+  else
+    self.position.y = ctx.resolution.y - 64
+  end
+
+  local movement = util.b2n(input_action_just_pressed{name = "right"}) - util.b2n(input_action_just_pressed{name = "left"})
+  if movement ~= 0 then
+    self.flip = movement < 0
+  end
+
+  if movement ~= 0 then
+    self.velocity.y = -10
+    self.velocity.x = movement * 20
+  end
+
+  if self.velocity.x < -0.1 or self.velocity.x > 0.1 then
+    self.spr_idx = (math.floor(ctx.frame_number / 11) % 2) + 1
+  end
+
+  self.position = self.position + self.velocity
+  draw_sprite{rect = self:rect(), texture = SPR[self.spr_idx], flip_x = self.flip}
+end
+
+return p

data/scripts/util.lua

@@ -0,0 +1,12 @@
+local util = {}
+
+function util.b2n(b)
+  return b and 1 or 0
+end
+
+function util.lerp(v1, v2, t)
+  -- return (1 - t) * v1 + t * v2
+  return v1 + t * (v2 - v1)
+end
+
+return util