base/aabb_collision.lua

   1 --these are functions for doing collision detection
   2
   3 --unless one wants to write their own routines, then the
   4 -- collide_Object_bounds() and collide_Object_Rects() shouldn't be used
   5 --
   6 -- Instead, please use the check_collisions_*() functions
   7
   8
   9 function collide_Object_bounds(a, b)
  10   --this is provided as a convenience so that one can make objects invisible to collisions
  11   if a.death_anim == true or b.death_anim == true then return false end
  12
  13   local x1, x2, y1, y2, x3, x4, y3, y4 = a.x, a.x + a.w, a.y, a.y + a.h, b.x, b.x + b.w, b.y, b.y + b.h
  14
  15   --fully contained
  16   if ((x1 >= x3 and x2 <= x4) and (y1 >= y3 and y2 <= y4)) or
  17     ((x3 >= x1 and x4 <= x2) and (y3 >= y1 and y4 <= y2)) then
  18     return true
  19   end
  20
  21   --top left corner
  22   if ((x1 >= x3 and x1 <= x4) and (y1 >= y3 and y1 <= y4)) or
  23     ((x3 >= x1 and x3 <= x2) and (y3 >= y1 and y3 <= y2)) then
  24     return true
  25   end
  26
  27   --top right corner
  28   if ((x2 >= x3 and x2 <= x4) and (y1 >= y3 and y1 <= y4)) or
  29     ((x4 >= x1 and x4 <= x2) and (y3 >= y1 and y3 <= y2)) then
  30     return true
  31   end
  32
  33   --bottom left corner
  34   if ((x1 >= x3 and x1 <= x4) and (y2 >= y3 and y2 <= y4)) or
  35     ((x3 >= x1 and x3 <= x2) and (y4 >= y1 and y4 <= y2)) then
  36     return true
  37   end
  38
  39   --bottom right corner
  40   if ((x1 >= x3 and x1 <= x4) and (y2 >= y3 and y2 <= y4)) or
  41     ((x3 >= x1 and x3 <= x2) and (y4 >= y1 and y4 <= y2)) then
  42     return true
  43   end
  44
  45   --top
  46   if ((x1 <= x3 and x2 >= x4) and (y1 >= y3 and y1 <= y4)) or
  47     ((x3 <= x1 and x4 >= x2) and (y3 >= y1 and y3 <= y2)) then
  48     return true
  49   end
  50
  51   --left
  52   if ((x1 <= x3 and x1 >= x4) and (y1 >= y3 and y2 <= y4)) or
  53     ((x3 <= x1 and x3 >= x2) and (y3 >= y1 and y4 <= y2)) then
  54     return true
  55   end
  56
  57   --right
  58   if ((x2 <= x3 and x2 >= x4) and (y1 >= y3 and y2 <= y4)) or
  59     ((x4 <= x1 and x4 >= x2) and (y3 >= y1 and y4 <= y2)) then
  60     return true
  61   end
  62
  63   --bottom
  64   if ((x1 <= x3 and x2 >= x4) and (y2 >= y3 and y2 <= y4)) or
  65     ((x3 <= x1 and x4 >= x2) and (y4 >= y1 and y4 <= y2)) then
  66     return true
  67   end
  68
  69   return false
  70 end
  71
  72
  73 function collide_Object_Rects(a, b)
  74   if a.death_anim or b.death_anim then return false end
  75
  76   local a_ids = ObjectList:new()
  77   local b_ids = ObjectList:new()
  78
  79   for r1 in a.rects:iterator() do
  80     for r2 in b.rects:iterator() do
  81
  82       local flag = false
  83
  84       local x1, x2, y1, y2, x3, x4, y3, y4 = r1.x+a.x, r1.x+a.x+a.w, r1.y+a.y, r1.y+a.y+a.h, r2.x+b.x, r2.x+b.x+b.w, r2.y+b.y, r2.y+b.y+b.h
  85
  86       --fully contained
  87       if ((x1 >= x3 and x2 <= x4) and (y1 >= y3 and y2 <= y4)) or
  88             ((x3 >= x1 and x4 <= x2) and (y3 >= y1 and y4 <= y2)) then
  89             flag = true
  90             if a_ids:exists(r1.id) == false then a_ids:push_back(r1.id) end
  91             if b_ids:exists(r2.id) == false then b_ids:push_back(r2.id) end
  92       end
  93
  94       --top left corner
  95       if flag == false and ((x1 >= x3 and x1 <= x4) and (y1 >= y3 and y1 <= y4)) or
  96             ((x3 >= x1 and x3 <= x2) and (y3 >= y1 and y3 <= y2)) then
  97             flag = true
  98             if a_ids:exists(r1.id) == false then a_ids:push_back(r1.id) end
  99             if b_ids:exists(r2.id) == false then b_ids:push_back(r2.id) end
 100       end
 101
 102       --top right corner
 103       if flag == false and ((x2 >= x3 and x2 <= x4) and (y1 >= y3 and y1 <= y4)) or
 104             ((x4 >= x1 and x4 <= x2) and (y3 >= y1 and y3 <= y2)) then
 105             flag = true
 106             if a_ids:exists(r1.id) == false then a_ids:push_back(r1.id) end
 107             if b_ids:exists(r2.id) == false then b_ids:push_back(r2.id) end
 108       end
 109
 110       --bottom left corner
 111       if flag == false and ((x1 >= x3 and x1 <= x4) and (y2 >= y3 and y2 <= y4)) or
 112             ((x3 >= x1 and x3 <= x2) and (y4 >= y1 and y4 <= y2)) then
 113             flag = true
 114             if a_ids:exists(r1.id) == false then a_ids:push_back(r1.id) end
 115             if b_ids:exists(r2.id) == false then b_ids:push_back(r2.id) end
 116       end
 117
 118       --bottom right corner
 119       if flag == false and ((x1 >= x3 and x1 <= x4) and (y2 >= y3 and y2 <= y4)) or
 120             ((x3 >= x1 and x3 <= x2) and (y4 >= y1 and y4 <= y2)) then
 121             flag = true
 122             if a_ids:exists(r1.id) == false then a_ids:push_back(r1.id) end
 123             if b_ids:exists(r2.id) == false then b_ids:push_back(r2.id) end
 124       end
 125
 126       --top
 127       if flag == false and ((x1 <= x3 and x2 >= x4) and (y1 >= y3 and y1 <= y4)) or
 128             ((x3 <= x1 and x4 >= x2) and (y3 >= y1 and y3 <= y2)) then
 129             flag = true
 130             if a_ids:exists(r1.id) == false then a_ids:push_back(r1.id) end
 131             if b_ids:exists(r2.id) == false then b_ids:push_back(r2.id) end
 132       end
 133
 134       --left
 135       if flag == false and ((x1 <= x3 and x1 >= x4) and (y1 >= y3 and y2 <= y4)) or
 136             ((x3 <= x1 and x3 >= x2) and (y3 >= y1 and y4 <= y2)) then
 137             flag = true
 138             if a_ids:exists(r1.id) == false then a_ids:push_back(r1.id) end
 139             if b_ids:exists(r2.id) == false then b_ids:push_back(r2.id) end
 140       end
 141
 142       --right
 143       if flag == false and ((x2 <= x3 and x2 >= x4) and (y1 >= y3 and y2 <= y4)) or
 144             ((x4 <= x1 and x4 >= x2) and (y3 >= y1 and y4 <= y2)) then
 145             flag = true
 146             if a_ids:exists(r1.id) == false then a_ids:push_back(r1.id) end
 147             if b_ids:exists(r2.id) == false then b_ids:push_back(r2.id) end
 148       end
 149
 150       --bottom
 151       if flag == false and ((x1 <= x3 and x2 >= x4) and (y2 >= y3 and y2 <= y4)) or
 152             ((x3 <= x1 and x4 >= x2) and (y4 >= y1 and y4 <= y2)) then
 153             flag = true
 154             if a_ids:exists(r1.id) == false then a_ids:push_back(r1.id) end
 155             if b_ids:exists(r2.id) == false then b_ids:push_back(r2.id) end
 156       end
 157
 158     end
 159   end
 160
 161   return a_ids, b_ids
 162 end
 163
 164
 165 --checks for collisions between two lists and calls the collide() function of each
 166 function check_collisions_lists(list1, list2)
 167   local id1, id2
 168   for obj1 in list1:iterator() do
 169     for obj2 in list2:iterator() do
 170       if obj1 ~= obj2 and collide_Object_bounds(obj1, obj2) then
 171         id1, id2 = collide_Object_Rects(obj1, obj2)
 172         obj1:collide(id1, obj2.type)
 173         obj2:collide(id2, obj1.type)
 174       end
 175     end
 176   end
 177 end
 178
 179 --checks for collisions between an object and a list
 180 function check_collisions_obj_list(obj, list2)
 181   local id1, id2
 182   for obj2 in list2:iterator() do
 183     if obj1 ~= obj2 and collide_Object_bounds(obj, obj2) then
 184       id1, id2 = collide_Object_Rects(obj, obj2)
 185       obj:collide(id1, obj2.type)
 186       obj2:collide(id2, obj.type)
 187     end
 188   end
 189 end
 190
 191 --checks for collisions between two objects
 192 function check_collisions_obj_obj(obj1, obj2)
 193   local id1, id2
 194   if obj1 ~= obj2 and collide_Object_bounds(obj1, obj2) then
 195     id1, id2 = collide_Object_Rects(obj1, obj2)
 196     obj1:collide(id1, obj2.type)
 197     obj2:collide(id2, obj1.type)
 198   end
 199 end
 200
 201 --checks for collisions between an object and a list. returns true or false.
 202 function check_collisions_any(obj, list)
 203   local id1, id2
 204   for obj2 in list2:iterator() do
 205     if collide_Object_bounds(obj, obj2) then
 206       id1, id2 = collide_Object_Rects(obj, obj2)
 207       if id1.size > 0 and id2.size > 0 then
 208         return true
 209       else
 210         return false
 211       end
 212     end
 213   end
 214 end