From 5c936df3f65b3f647f04ffda8c94eb0cd9b0c98c Mon Sep 17 00:00:00 2001
From: ari melody <ari@arimelody.me>
Date: Fri, 30 Aug 2024 12:30:53 +0100
Subject: [PATCH] (hopefully) improved reconciliation

---
 client/js/main.js | 127 +++++++++++++++++++++++++++++++++-------------
 server/ws.js      |   4 ++
 2 files changed, 95 insertions(+), 36 deletions(-)

diff --git a/client/js/main.js b/client/js/main.js
index de9d254..4325f9d 100644
--- a/client/js/main.js
+++ b/client/js/main.js
@@ -109,23 +109,32 @@ function start() {
                 break;
             case "update": {
                 server_tick = data.tick;
+                var prediction = predictions[data.tick];
+                if (prediction) {
+                    Object.keys(predictions).forEach(tick => {
+                        if (tick < data.tick) delete predictions[tick];
+                    });
+                    server_ping = new Date() - prediction.time;
+                }
                 Object.keys(data.players).forEach(id => {
                     const player = players[id];
                     const update = data.players[id];
-                    // this should never be true, but just in case
-                    if (!player) return;
                     if (id == client_id) {
-                        // clear all predictions prior to this tick
-                        Object.keys(predictions).forEach(tick => {
-                            if (tick < data.tick) delete predictions[tick];
-                        });
-                        var prediction = predictions[data.tick];
                         if (!prediction) return;
-                        server_ping = new Date() - prediction.time;
-                        if (Math.abs(prediction.x - update.x) > 1)
-                            players[client_id].x = update.x;
-                        if (Math.abs(prediction.y - update.y) > 1)
-                            players[client_id].y = update.y;
+                        const predicted = prediction.player;
+                        // clear all predictions prior to this tick
+                        if (predicted != update) {
+                            var diff_x = predicted.x - update.x;
+                            var diff_y = predicted.y - update.y;
+                            // apply difference to all predictions
+                            Object.values(predictions).forEach(p => {
+                                p.x -= diff_x;
+                                p.y -= diff_y;
+                            });
+                            // update client state to reflect
+                            player.x -= diff_x;
+                            player.y -= diff_y;
+                        }
                         delete predictions[data.tick];
                     } else {
                         player.x = update.x;
@@ -135,9 +144,33 @@ function start() {
                 Object.keys(data.props).forEach(id => {
                     const prop = props[id];
                     const update = data.props[id];
+                    if (!prediction) {
+                        prop.x = update.x;
+                        prop.y = update.y;
+                        prop.xv = update.xv;
+                        prop.yv = update.yv;
+                        return;
+                    }
 
-                    prop.x = update.x;
-                    prop.y = update.y;
+                    const predicted = prediction.props[id];
+                    if (predicted != update) {
+                        var diff_x = predicted.x - update.x;
+                        var diff_y = predicted.y - update.y;
+                        var diff_xv = predicted.xv - update.xv;
+                        var diff_yv = predicted.yv - update.yv;
+                        // apply difference to all predictions
+                        Object.values(predictions).forEach(p => {
+                            p.x -= diff_x;
+                            p.y -= diff_y;
+                            p.xv -= diff_xv;
+                            p.yv -= diff_yv;
+                        });
+                        // update client state to reflect
+                        prop.x -= diff_x;
+                        prop.y -= diff_y;
+                        prop.xv -= diff_xv;
+                        prop.yv -= diff_yv;
+                    }
                 });
                 break;
             }
@@ -211,6 +244,10 @@ function start() {
 
 canvas.addEventListener("keypress", event => {
     switch (event.key.toLowerCase()) {
+        case 'i':
+            enable_interpolation.update(val => !val);
+            interpolationToggle.checked = enable_interpolation.get();
+            break;
         case 'p':
             console.log(predictions);
             break;
@@ -288,31 +325,49 @@ function sendChat(msg) {
 }
 
 function update(delta) {
+    const prediction = {
+        time: new Date(),
+        player: {},
+        props: {},
+    };
+
     const clientPlayer = players[client_id];
-    if (clientPlayer) {
-        clientPlayer.in_x = input.move_right - input.move_left;
-        clientPlayer.in_y = input.move_down - input.move_up;
+    if (!clientPlayer) return;
 
-        clientPlayer.update(delta);
+    clientPlayer.in_x = input.move_right - input.move_left;
+    clientPlayer.in_y = input.move_down - input.move_up;
 
-        // insert prediction for the next server tick
-        predictions[ticks] = {
-            time: new Date(),
-            x: clientPlayer.x,
-            y: clientPlayer.y,
+    clientPlayer.update(delta);
+
+    // insert prediction for the next server tick
+    prediction.player = {
+        x: clientPlayer.x,
+        y: clientPlayer.y,
+    };
+
+    var t = ticks;
+    setTimeout(() => {
+        if (!ws) return;
+        ws.send(JSON.stringify({
+            type: "update",
+            tick: t,
+            x: input.move_right - input.move_left,
+            y: input.move_down - input.move_up,
+        }));
+    }, fake_ping.get() / 2);
+
+    Object.keys(props).forEach(id => {
+        const prop = props[id];
+        prop.update(delta, Object.values(players));
+        prediction.props[id] = {
+            x: prop.x,
+            y: prop.y,
+            xv: prop.xv,
+            yv: prop.yv,
         };
+    });
 
-        var t = ticks;
-        setTimeout(() => {
-            if (!ws) return;
-            ws.send(JSON.stringify({
-                type: "update",
-                tick: t,
-                x: input.move_right - input.move_left,
-                y: input.move_down - input.move_up,
-            }));
-        }, fake_ping.get() / 2);
-    }
+    predictions[ticks] = prediction;
 
     ticks++;
 }
@@ -337,8 +392,8 @@ function draw() {
         const server_state = Object.values(predictions)[0];
         ctx.fillStyle = "#208020";
         ctx.beginPath();
-        ctx.rect(server_state.x - Player.SIZE / 2,
-            server_state.y - Player.SIZE / 2,
+        ctx.rect(server_state.player.x - Player.SIZE / 2,
+            server_state.player.y - Player.SIZE / 2,
             Player.SIZE, Player.SIZE);
         ctx.stroke();
     }
diff --git a/server/ws.js b/server/ws.js
index a387592..f383cb5 100644
--- a/server/ws.js
+++ b/server/ws.js
@@ -88,6 +88,8 @@ export function init(http_server) {
                                 name: prop.name,
                                 x: prop.x,
                                 y: prop.y,
+                                xv: prop.xv,
+                                yv: prop.yv,
                                 col: prop.colour,
                                 sprite: prop.sprite,
                             }
@@ -193,6 +195,8 @@ function update() {
         frame_props[id] = {
             x: prop.x,
             y: prop.y,
+            xv: prop.xv,
+            yv: prop.yv,
         }
     });