Add animated sprite example

examples/animated_sprite.cr

@@ -0,0 +1,36 @@
+require "../src/game"
+require "../src/sprite"
+require "../src/pixel_text"
+
+module PF
+  class SpriteExample < Game
+    @text : PixelText = PixelText.new("assets/pf-font.png")
+
+    @tiles : Array(Sprite)
+    @frame = 0
+    @sub_frame = 0.0
+    @frame_time = 0.1
+
+    def initialize(*args, **kwargs)
+      super
+      @tiles = Sprite.load_tiles("assets/walking.png", 32, 64)
+    end
+
+    def update(dt, event)
+      @sub_frame += dt
+      if @sub_frame > @frame_time
+        @sub_frame = @sub_frame % @frame_time
+        @frame = (@frame + 1) % @tiles.size
+      end
+    end
+
+    def draw
+      clear(60, 120, 200)
+      @text.draw_to(screen, "Frame: #{@frame}", 5, 5)
+      @tiles[@frame].draw_to(screen, (viewport // 2) - @tiles[@frame].size // 2)
+    end
+  end
+end
+
+game = PF::SpriteExample.new(120, 80, 5)
+game.run!