Find unattached bubbles and make them fall

main.lua

@@ -132,6 +132,45 @@ local function find_matches(start_index)
   return matches
 end
 
+local function find_unattached_bubbles()
+  local to_check = {}
+  local visited = {}
+  local attached = {}
+  local unattached = {}
+
+  -- start with top row bubbles attached to the ceiling
+  for i = 1, #game.levels[game.current_level][1] do
+    if game.bubble_slots[i].bubble_type ~= 0 then
+      to_check[#to_check+1] = i
+      attached[i] = true
+    end
+    visited[i] = true
+  end
+
+  while #to_check > 0 do
+    local current_index = table.remove(to_check)
+    local slot = game.bubble_slots[current_index]
+
+    for i = 1, #slot.neighbours do
+      local neighbour_index = slot.neighbours[i]
+      local neighbour = game.bubble_slots[neighbour_index]
+      if not visited[neighbour_index] and neighbour.bubble_type ~= 0 then
+        attached[neighbour_index] = true
+        to_check[#to_check+1] = neighbour_index
+      end
+      visited[neighbour_index] = true
+    end
+  end
+
+  for i = 1, #game.bubble_slots do
+    if game.bubble_slots[i].bubble_type ~= 0 and not attached[i] then
+      unattached[#unattached+1] = i
+    end
+  end
+
+  return unattached
+end
+
 function love.load(arg)
   if arg[#arg] == "debug" then require("lldebugger").start() end
 
@@ -229,6 +268,7 @@ function love.load(arg)
   }
 
   game.bursting_bubbles = {}
+  game.falling_bubbles = {}
 end
 
 function love.update(dt)
@@ -298,6 +338,8 @@ function love.update(dt)
 
       local matches = find_matches(nearest_slot_index)
       if #matches >= 3 then
+        game.next_bubble = nil
+
         -- remove matches
         for i = 1, #matches do
           local index = matches[i]
@@ -310,7 +352,20 @@ function love.update(dt)
           }
           game.bubble_slots[index].bubble_type = 0
         end
-        game.next_bubble = nil
+
+        -- remove unattached bubbles
+        local unattached = find_unattached_bubbles()
+        for i = 1, #unattached do
+          local index = unattached[i]
+          game.falling_bubbles[#game.falling_bubbles+1] = {
+            x = game.bubble_slots[index].x,
+            y = game.bubble_slots[index].y,
+            velocity_x = i % 2 == 0 and -2 or 2,
+            velocity_y = love.math.random(-2.0, -5.0),
+            bubble_type = game.bubble_slots[index].bubble_type
+          }
+          game.bubble_slots[index].bubble_type = 0
+        end
       end
 
       -- calculate remaining bubble types
@@ -352,6 +407,23 @@ function love.update(dt)
     end
   end
 
+  if #game.falling_bubbles > 0 then
+    for i = #game.falling_bubbles, 1, -1 do
+      local bubble = game.falling_bubbles[i]
+      bubble.x = bubble.x + bubble.velocity_x
+      bubble.y = bubble.y + bubble.velocity_y
+      bubble.velocity_x = bubble.velocity_x * 0.99
+      bubble.velocity_y = bubble.velocity_y + 0.3 -- gravity 0.3
+      if bubble.x - game.bubble_radius <= game.level_left or
+         bubble.x + game.bubble_radius >= game.level_right then
+        bubble.velocity_x = -bubble.velocity_x
+      end
+      if bubble.y - game.bubble_radius > game.window_height then
+        table.remove(game.falling_bubbles, i)
+      end
+    end
+  end
+
   if game.frame_by_frame then
     game.paused = true
     game.frame_by_frame = false
@@ -414,6 +486,7 @@ function love.draw(alpha)
     game.launcher_offset_y
   )
 
+  -- draw bursting bubbles
   if #game.bursting_bubbles > 0 then
     for i = 1, #game.bursting_bubbles do
       local bubble = game.bursting_bubbles[i]
@@ -431,6 +504,24 @@ function love.draw(alpha)
     end
   end
 
+  -- draw falling bubbles
+  if #game.falling_bubbles > 0 then
+    for i = 1, #game.falling_bubbles do
+      local bubble = game.falling_bubbles[i]
+      love.graphics.setColor(1, 1, 1, bubble.alpha)
+      love.graphics.draw(
+        game.bubble_images[bubble.bubble_type],
+        bubble.x + bubble.velocity_x * alpha,
+        bubble.y + bubble.velocity_y * alpha,
+        0,
+        bubble.scale,
+        bubble.scale,
+        game.bubble_radius,
+        game.bubble_radius
+      )
+    end
+  end
+
   -- draw next bubble
   -- if moving, extrapolate position based on alpha value from love.run
   if game.next_bubble then