Fix can_move constants to remove path dependence

previous attempt tried to use shifts to get 0.4 to 0.2 or 0.8 and multiplication to get -0.8, forgetting that the multiplication would also turn 0.4 into 0 along the way. oops. I got ratholed on the mathematical approach, but a very straightforward lookup table can get more done.

Reviewed-on: pyrex/chameleonic#14
Co-authored-by: Kistaro Windrider <kistaro@gmail.com>
Co-committed-by: Kistaro Windrider <kistaro@gmail.com>

chameleonic.p8

@@ -531,6 +531,8 @@ function level:get_latch(dx,dy,px,py)
 	end
 end
 
+ropecheck=split"-0.6,0.4,0.4"
+
 function level:can_move(
  is_player,
  mx0,my0,dmx,dmy,exclude_src,exclude_dst
@@ -542,17 +544,9 @@ function level:can_move(
  if (self:mcoll(mx1,my1) or player.x==mx1 and player.y==my1) return false
 
  if player.rope then
-  local chk=false
+  local w,h=1.2,0.2
-  local w,h=1.6,0.2
+  if (dmx==0) w,h=0.2,1.2
-  if (dmx==0) w,h=0.2,1.6
+  if (player.rope:collide_mrect(mx0+ropecheck[dmx+2],my0+ropecheck[dmy+2],w,h,exclude_src,exclude_dst)) return false
-
-  local rectx,recty
-  if (dmy==-1) rectx,recty=0.4,-0.8
-  if (dmy==1) rectx,recty=0.4,0.2
-  if (dmx==-1) rectx,recty=-0.8,0.4
-  if (dmx==1) rectx,recty=0.2,0.4
-
-  if (player.rope:collide_mrect(mx0+rectx,my0+recty,w,h,exclude_src,exclude_dst)) return false
  end
  
  return true