Improved Bomberman movement

game/dim.fnl

@@ -1 +1,5 @@
-{:tilesize 32}
+(local dim {})
+(set dim.tilesize 32)
+(set dim.halftile (/ dim.tilesize 2))
+
+dim

game/entities/bomb.fnl

@@ -28,7 +28,7 @@
 
 (fn Bomb.explode [bomb rules]
   (Bomb.set-state bomb :exploding 0.5)
-  (set bomb.solid nil)
+  (set bomb.bomb nil)
   (set bomb.deadly true)
   (rules.explode-bomb bomb))
 
@@ -40,7 +40,7 @@
       :exploding (rules.clear-bomb bomb))))
 
 (fn Bomb.new []
-  {:state :ticking :timer 3 :solid true :draw #(Bomb.draw $...) :update #(Bomb.update $...)})
+  {:state :ticking :timer 3 :bomb true :draw #(Bomb.draw $...) :update #(Bomb.update $...)})
 
 (fn Bomb.new-explosion []
   {:state :exploding :timer 0.5 :deadly true :draw #(Bomb.draw $...) :update #(Bomb.update $...)})

game/entities/bomberman.fnl

@@ -1,7 +1,7 @@
 (local util (require :lib.util))
 (local dim (require :game.dim))
 (local {: direct : move} (util.require :game.entity))
-(local {: edge : vec*} (util.require :game.helpers))
+(local {: edge : edge-crosses : vec*} (util.require :game.helpers))
 (local map (require :game.tilemap))
 
 (local bomberman (util.hot-table ...))
@@ -11,21 +11,63 @@
   (love.graphics.setColor 0.2 0.2 0.2)
   (love.graphics.circle :fill (. entity.pos 1) (. entity.pos 2) (/ dim.tilesize 2)))
 
-(fn collides? [x y rules]
+(fn tile-at [x y rules]
   (-?> [x y]
     (map.world-to-tile)
-    (rules.tile-at)
+    (rules.tile-at)))
-    (. :solid)))
+
+(fn wall-collides? [x y rules]
+  (-?> (tile-at x y rules)
+    (. :wall)))
+
+(fn bomb-collides? [x y rules]
+  (-?> (tile-at x y rules)
+    (. :bomb)))
+
+(fn bomberman.collides? [[x y] rules]
+  (let [tile (tile-at x y rules)]
+    (and tile (or tile.bomb tile.wall))))
+
+(fn bomberman.tile-edge [c dc]
+  (let [tc (math.floor (/ c dim.tilesize))
+        cfloor (* tc dim.tilesize)]
+    (if (= dc 0) c
+        (> dc 0) (- cfloor dim.halftile)
+      (+ cfloor dim.tilesize dim.halftile))))
+
+; Collision model for Bomberman works like this (in order):
+; * if the moving edge is NOT crossing over a tile boundary, allow the movement
+; * if there is no solid tile in in front of Bomberman, allow the movement
+; * if there are two solid tiles in front of Bomberman, push Bomberman back onto
+;   the tile boundary
+; * if there is one solid and one empty tile in front of Bomberman, push Bomberman
+;   back onto the tile boundary, and push Bomberman towards the empty tile in the
+;   other axis
+; repeat for both x and y axis
+; TODO: do we add the two vectors? is it acceptable that diagonal movement is faster?
+(fn horizontal [x y] (fn [dx dy] [(+ x dx) (+ y dy)]))
+(fn vertical [x y]   (fn [dy dx] [(+ x dx) (+ y dy)]))
+(fn bomberman.axis-movement [off c copp dc rules]
+  (let [d (fn [cnew] (- cnew c))
+       (edge-prev edge-next) (edge c dc dim.halftile)
+        crosses (edge-crosses edge-prev edge-next dim.tilesize)
+        neg-collides (bomberman.collides? (off (d edge-next) (- dim.halftile)) rules)
+        pos-collides (bomberman.collides? (off (d edge-next) (- dim.halftile 0.01)) rules)
+        dc-edge (d (bomberman.tile-edge edge-next dc))
+        dcopp (math.abs dc)]
+    (if (not crosses) [dc 0]
+        (and (not neg-collides) (not pos-collides)) [dc 0]
+        (and neg-collides pos-collides) [dc-edge 0]
+        neg-collides [dc-edge (math.min dcopp (- (bomberman.tile-edge (+ copp dim.tilesize (- dim.halftile 0.01)) 1) copp))]
+        pos-collides [dc-edge (math.max (- dcopp) (- (bomberman.tile-edge (- copp dim.tilesize dim.halftile) -1) copp))])))
 
 (fn bomberman.update [entity dt rules]
   (set entity.vel (direct bomberman.keymap (* dim.tilesize 3)))
   (local [x y] entity.pos)
   (local [dx dy] (vec* entity.vel dt))
-  (let [xedge (edge x dx (/ dim.tilesize 2))
+  (let [[dx1 dy1] (bomberman.axis-movement (horizontal x y) x y dx rules)
-        xn (if (collides? xedge y rules) x (+ x dx))
+        [dy2 dx2] (bomberman.axis-movement (vertical x y) y x dy rules)]
-        yedge (edge y dy (/ dim.tilesize 2))
+    (set entity.pos [(+ x dx1 dx2) (+ y dy1 dy2)]))
-        yn (if (collides? x yedge rules) y (+ y dy))]
-    (set entity.pos [xn yn]))
   (when (love.keyboard.isDown bomberman.keymap.bomb)
     (rules.place-bomb (map.world-to-tile entity.pos))))
 

game/helpers.fnl

@@ -34,8 +34,13 @@
 
 (fn edge [c dc neg-offset ?pos-offset]
   (local pos-offset (if (= ?pos-offset nil) neg-offset ?pos-offset))
-  (if (= dc 0) c
+  (if (= dc 0) (values c c)
-      (< dc 0) (+ c dc (- neg-offset))
+      (< dc 0) (values (- c neg-offset) (+ c dc (- neg-offset)))
-    (+ c dc pos-offset)))
+    (values (+ c pos-offset) (+ c dc pos-offset))))
 
-{: dir-from-key : vec* : vec+ : vec-op : all-coordinates : edge}
+(fn edge-crosses [c1 c2 width]
+  (if (= c1 c2) false
+      (or (= (% c1 width) 0) (= (% c2 width) 0)) true
+    (not= (math.floor (/ c1 width)) (math.floor (/ c2 width)))))
+
+{: dir-from-key : vec* : vec+ : vec-op : all-coordinates : edge : edge-crosses}

game/tilemap.fnl

@@ -67,11 +67,6 @@
   (-> vec
     ((vec-op #(math.floor (/ $1 dim.tilesize))))))
 
-(fn colliding-tile-xy [vec dir]
-  (-> vec
-    (world-to-tile)
-    (vec+ dir)))
-
 {: new-tilemap : itile-at :   tile-at : set-itile-at : tile-at-overlay : draw-tilemaps
  : new-entitymap : set-entity-at : remove-entity : update-entitymap
  : world-to-tile}

game/tiles.fnl

@@ -29,9 +29,9 @@
   [{:name :empty
     :empty true}
    {:name :strongwall
-    :solid true}
+    :wall true}
    {:name :weakwall
-    :solid true
+    :wall true
     :breakable true}
    {:name :dot
     :edible true}