Rpg Maker Developers Group

#---------------------------------------------------------------------
# Line of Sight
#---------------------------------------------------------------------
 
 def lineofsight
 
   #variable names are self explanitory
   distance = $game_variables[43]
   targetx = $game_variables[23]
   targety = $game_variables[24]
   attackerx = $game_variables[6]
   attackery = $game_variables[7]
 
   #dy and dx are deltas used for calculating x's per y or vice versa
   dy = 0
   dx = 0
 
   # x and y are the final values of the coordinates for each grid step
   x = attackerx
   y = attackery
 
   #This first section determines the direction we are moving
   #and is sets our dx and dy values for our delta int he second part
   quadrantx = attackerx - targetx
   quadranty = attackery - targety
 
     #First Quadrant
     if quadrantx < 0 and quadranty < 0
 
       dx = targetx - attackerx
       dy = targety - attackery
   
     #Second Quadrant
     elsif quadrantx < 0 and quadranty > 0
 
       dx = targetx - attackerx
       dy = attackery - targety
   
     #Third Quadrant
     elsif quadrantx > 0 and quadranty > 0
 
       dx = attackerx - targetx
       dy = attackery - targety
   
     #Fourth Quadrant
     elsif quadrantx > 0 and quadranty < 0
 
       dx = attackerx - targetx
       dy = targety - attackery
 
     end
 
 
   delta = 2*dy-dx
 
 
  #This loop calculates the x and y of each square in our line
  #and checks for solid objects
  #delta helps us determine if we have made the right number of x or y steps
  #if we have it swaps the variable we change that time around and resets
  for checked in 1..distance
 
     #First Quadrant
     if quadrantx < 0 and quadranty < 0
 
       if delta > 0
       y = y + 1
       delta = delta - 2*dx
 
       end
 
     checked = checked + 1 # for the for loop
     x = x + 1
     delta = delta + 2*dy
 
     #Second Quadrant
     elsif quadrantx < 0 and quadranty > 0
 
       if delta > 0
       y = y - 1
       delta = delta - 2*dx
 
       end
 
     checked = checked + 1 # for the for loop
     x = x + 1
     delta = delta + 2*dy
 
     #Third Quadrant
     elsif quadrantx > 0 and quadranty > 0
 
       if delta > 0
       y = y - 1
       delta = delta - 2*dx
 
       end
 
     checked = checked + 1 # for the for loop
     x = x - 1
     delta = delta + 2*dy
 
     #Fourth Quadrant
     elsif quadrantx > 0 and quadranty < 0
 
       if delta > 0
       y = y + 1
       delta = delta - 2*dx
 
       end
 
     checked = checked + 1 # for the for loop
     x = x - 1
     delta = delta + 2*dy

     #Vertical down
     elsif quadrantx == 0 and quadranty < 0
 
       y = y + 1
   
     #Vertical up
     elsif quadrantx == 0 and quadranty > 0
   
       y = y - 1
   
     #Horizontal right
     elsif quadrantx < 0 and quadranty == 0
 
       x = x + 1
   
     #Horizontal left
     elsif quadrantx > 0 and quadranty == 0
 
       x = x - 1
   
     end
 
 
 
     #this checks the square to see if a solid object is occupying it
 
      if $game_map.region_id(x, y) == 1 #region one marks a solid object
   
        #this is the switch for the event to tell the player if the shot is valid or not
        $game_switches[19] = true
   
      end

    end
 
 
end