From 09eb03dad6e05258d578fb14efa4dd7d72559fe5 Mon Sep 17 00:00:00 2001
From: "Eevee (Evelyn Woods)" <eevee.git@veekun.com>
Date: Wed, 21 Oct 2020 21:24:59 -0600
Subject: [PATCH] Iterate actors in reverse order to match Lynx/CC2 (fixes #7)

---
 js/game.js      | 28 ++++++++++++++++------------
 js/main.js      |  1 +
 js/tiletypes.js |  3 ++-
 3 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/js/game.js b/js/game.js
index 38194cd..c7f4ea3 100644
--- a/js/game.js
+++ b/js/game.js
@@ -253,22 +253,18 @@ export class Level {
 
                     if (tile.type.is_player) {
                         // TODO handle multiple players, also chip and melinda both
-                        // TODO complain if no chip
+                        // TODO complain if no player
                         this.player = tile;
-                        // Always put the player at the start of the actor list
-                        // (accomplished traditionally with a swap)
-                        this.actors.push(this.actors[0]);
-                        this.actors[0] = tile;
                     }
-                    else if (tile.type.is_actor) {
+                    if (tile.type.is_actor) {
                         if (has_cloner) {
                             // TODO is there any reason not to add clone templates to the actor
                             // list?
                             tile.stuck = true;
                         }
-                        else {
-                            this.actors.push(tile);
-                        }
+                    }
+                    if (! tile.stuck) {
+                        this.actors.push(tile);
                     }
                     cell._add(tile);
 
@@ -373,7 +369,13 @@ export class Level {
         // immediately), we still want every time's animation to finish, or it'll look like some
         // objects move backwards when the death screen appears!
         let cell_steppers = [];
-        for (let actor of this.actors) {
+        // Note that we iterate in reverse order, DESPITE keeping dead actors around with null
+        // cells, to match the Lynx and CC2 behavior.  This is actually important in some cases;
+        // check out the start of CCLP3 #54, where the gliders will eat the blue key immediately if
+        // they act in forward order!  (More subtly, even the earlier passes do things like advance
+        // the RNG, so for replay compatibility they need to be in reverse order too.)
+        for (let i = this.actors.length - 1; i >= 0; i--) {
+            let actor = this.actors[i];
             // Actors with no cell were destroyed
             if (! actor.cell)
                 continue;
@@ -423,7 +425,8 @@ export class Level {
         }
 
         // Second pass: actors decide their upcoming movement simultaneously
-        for (let actor of this.actors) {
+        for (let i = this.actors.length - 1; i >= 0; i--) {
+            let actor = this.actors[i];
             if (! actor.cell)
                 continue;
 
@@ -592,7 +595,8 @@ export class Level {
         }
 
         // Third pass: everyone actually moves
-        for (let actor of this.actors) {
+        for (let i = this.actors.length - 1; i >= 0; i--) {
+            let actor = this.actors[i];
             if (! actor.cell)
                 continue;
 
diff --git a/js/main.js b/js/main.js
index 81d53a6..819d01a 100644
--- a/js/main.js
+++ b/js/main.js
@@ -1349,6 +1349,7 @@ class Splash extends PrimaryView {
                 continue;
 
             let ext = m[1];
+            // TODO this can't load an individual c2m, hmmm
             if (ext === 'c2g' || ext === 'dat' || ext === 'ccl') {
                 let buf = await source.get(path);
                 await this.conductor.parse_and_load_game(buf, source, path);
diff --git a/js/tiletypes.js b/js/tiletypes.js
index 719c8a3..3e55c8b 100644
--- a/js/tiletypes.js
+++ b/js/tiletypes.js
@@ -882,7 +882,8 @@ const TILE_TYPES = {
             level.sfx.play_once('button-press', me.cell);
 
             // Move all yellow tanks one tile in the direction of the pressing actor
-            for (let actor of level.actors) {
+            for (let i = level.actors.length - 1; i >= 0; i--) {
+                let actor = level.actors[i];
                 // TODO generify somehow??
                 if (actor.type.name === 'tank_yellow') {
                     level.attempt_step(actor, other.direction);