From c13e5a684814d717a4a48f3babf84a7b5aa86868 Mon Sep 17 00:00:00 2001
From: "A.Olokhtonov" <a.olokhtonov@norsi-trans.ru>
Date: Sun, 5 May 2024 01:09:15 +0300
Subject: [PATCH] Smooth zooming

---
 README.txt                |  6 ++++--
 client/index.js           |  2 ++
 client/webgl_draw.js      | 20 ++++++++++++++++++++
 client/webgl_listeners.js | 20 +++++---------------
 4 files changed, 31 insertions(+), 17 deletions(-)

diff --git a/README.txt b/README.txt
index 8e8197f..7a99dad 100644
--- a/README.txt
+++ b/README.txt
@@ -17,6 +17,7 @@ Release:
         + Stroke previews get connected when drawn without panning on touch devices
         + Redraw HTML (cursors) on local canvas moves
         + New strokes dissapear on the HMH desk 
+        - Color picker misses on strange line endings
     - Debug
         - Restore ability to limit event range
     * Listeners/events/multiplayer
@@ -24,6 +25,7 @@ Release:
         + Fix blinking own stroke inbetween SYN->server and SYN->client
         + Drag with mouse button 3
         + Investigate skipped inputs on mobile (panning, zooming) [Events were not actually getting skipped. The stroke previews were just not being drawn]
+        + Smooth zoom
         - Be able to have multiple "current" strokes per player. In case of bad internet this can happen!
         - Do NOT use session id as player id LUL
         - Save events to indexeddb (as some kind of a blob), restore on reconnect and page reload
@@ -35,7 +37,7 @@ Release:
         + Follow player
         + Color picker (or at the very least an Open Color color pallete)
         + EYE DROPPER!
-        - Dynamic svg cursor to represent the brush
+        * Dynamic svg cursor to represent the brush
         - Eraser
         - Line drawing
         - Undo/redo
@@ -46,7 +48,7 @@ Release:
         - Set up VAOs
         - We are calling "geometry_prepare_stroke" twice for some reason
     - Presentation / "marketing"
-        - Title
+        - Title (InfiNotes?)
         - Icon
         - Product page (github readme, demo videos)
 
diff --git a/client/index.js b/client/index.js
index 0d220d8..6b23fe6 100644
--- a/client/index.js
+++ b/client/index.js
@@ -142,6 +142,8 @@ async function main() {
             'offset': { 'x': 0, 'y': 0 },
             'zoom_level': 0,
             'zoom': 1.0,
+            'target_zoom': 1.0,
+            'zoom_screenp': {'x': 0, 'y': 0},
         },
 
         'cursor': {
diff --git a/client/webgl_draw.js b/client/webgl_draw.js
index 2ff67a4..fddde52 100644
--- a/client/webgl_draw.js
+++ b/client/webgl_draw.js
@@ -289,4 +289,24 @@ async function draw(state, context) {
             schedule_draw(state, context);
         }
     }
+
+    if (state.canvas.target_zoom != state.canvas.zoom) {
+        update_canvas_zoom(state, state.canvas.zoom, state.canvas.target_zoom);
+        schedule_draw(state, context);
+    }
+}
+
+function update_canvas_zoom(state, current, target) {
+    if (Math.abs(1.0 - current / target) > 0.01) {
+        state.canvas.zoom = current + (target - current) * 0.2;
+    } else {
+        state.canvas.zoom = target;
+    }
+
+    // https://gist.github.com/aolo2/a373363419bd5a9283977ab9f8841f78
+    const zc = state.canvas.zoom_screenp;
+    state.canvas.offset.x = zc.x - (zc.x - state.canvas.offset.x) * state.canvas.zoom / current;
+    state.canvas.offset.y = zc.y - (zc.y - state.canvas.offset.y) * state.canvas.zoom / current;
+
+    update_cursor(state);
 }
diff --git a/client/webgl_listeners.js b/client/webgl_listeners.js
index 816058b..7b3d0a6 100644
--- a/client/webgl_listeners.js
+++ b/client/webgl_listeners.js
@@ -393,8 +393,6 @@ function update_cursor(state) {
 
 function wheel(e, state, context) {
     const screenp = {'x': window.devicePixelRatio * e.clientX, 'y': window.devicePixelRatio * e.clientY};
-    const canvasp = screen_to_canvas(state, screenp);
-
     const zooming_in = e.deltaY < 0;
     const zoom_level = zooming_in ? state.canvas.zoom_level + 1 : state.canvas.zoom_level - 1;
 
@@ -402,24 +400,16 @@ function wheel(e, state, context) {
         return;
     }
 
-    state.canvas.zoom_level = zoom_level;
-
     const dz = (zoom_level > 0 ? config.zoom_delta : -config.zoom_delta);
-    const old_zoom = state.canvas.zoom;
-    const new_zoom = Math.pow(1.0 + dz, Math.abs(zoom_level))
-
+    state.canvas.zoom_level = zoom_level;
+    state.canvas.target_zoom = Math.pow(1.0 + dz, Math.abs(zoom_level))
+    state.canvas.zoom_screenp = screenp;
+    
     // If we are moving our canvas, we don't need to follow anymore
     if (state.following_player !== null) {
         toggle_follow_player(state, state.following_player);
     }
-
-    // https://gist.github.com/aolo2/a373363419bd5a9283977ab9f8841f78
-    state.canvas.offset.x = screenp.x - (screenp.x - state.canvas.offset.x) * new_zoom / old_zoom;
-    state.canvas.offset.y = screenp.y - (screenp.y - state.canvas.offset.y) * new_zoom / old_zoom;
-
-    state.canvas.zoom = new_zoom;
-
-    update_cursor(state);
+   
     fire_event(state, movecanvas_event(state));
     schedule_draw(state, context);
 }