From 1074ece0c638abee35384cef513017af3651c8e0 Mon Sep 17 00:00:00 2001
From: Nils Pukropp <nils@narl.io>
Date: Sun, 1 Nov 2026 21:13:55 +0100
Subject: [PATCH] added debug

---
 web/src/blob/blob.ts | 20 +++++++++++++++++++-
 web/src/debug.ts     | 17 ++++++++++++++++-
 web/src/style.css    |  2 ++
 web/src/visual.ts    | 12 +++++++++---
 4 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/web/src/blob/blob.ts b/web/src/blob/blob.ts
index 83d0aa9..bc7a8fc 100644
--- a/web/src/blob/blob.ts
+++ b/web/src/blob/blob.ts
@@ -65,6 +65,8 @@ export interface DropState {
 }
 
 export class LiquidBlob {
+  /// Why the last `create` gave up, for `?debug=drop`.
+  static failure = "";
   readonly canvas = document.createElement("canvas");
   /// Called if the GPU drops the context; the page shows plain art until `onRestored`.
   onLost: (() => void) | null = null;
@@ -113,7 +115,8 @@ export class LiquidBlob {
     try {
       return new LiquidBlob(touch);
     } catch (err) {
-      console.warn("liquid visuals off:", (err as Error).message);
+      LiquidBlob.failure = (err as Error).message;
+      console.warn("liquid visuals off:", LiquidBlob.failure);
       return null;
     }
   }
@@ -391,6 +394,21 @@ export class LiquidBlob {
     );
   }
 
+  /// What `?debug=drop` shows: the GPU, and how far the drop got.
+  describe(): string {
+    const gl = this.gl;
+    const info = gl.getExtension("WEBGL_debug_renderer_info");
+    const gpu = info ? gl.getParameter(info.UNMASKED_RENDERER_WEBGL) : gl.getParameter(gl.RENDERER);
+    const hp = gl.getShaderPrecisionFormat(gl.VERTEX_SHADER, gl.HIGH_FLOAT);
+    return [
+      `gpu ${gpu}`,
+      `vertex highp ${hp ? hp.precision : "?"} bits`,
+      `ready ${this.ready} · lost ${gl.isContextLost()} · error ${gl.getError()}`,
+      `morph ${this.morph.toFixed(2)} · quality ${this.quality} · canvas ${this.canvas.width}x${this.canvas.height}`,
+      `in page ${this.canvas.isConnected} · css ${this.canvas.clientWidth}x${this.canvas.clientHeight}`,
+    ].join("\n");
+  }
+
   /// Stepped down to the lowest quality: the GPU had trouble keeping up.
   get struggling(): boolean {
     return this.quality === QUALITY.length - 1;
diff --git a/web/src/debug.ts b/web/src/debug.ts
index 3894e91..607fe6b 100644
--- a/web/src/debug.ts
+++ b/web/src/debug.ts
@@ -1,5 +1,6 @@
 // `?debug=audio`: live bars of what features.ts hears, for tuning its constants by
-// ear. Loaded only when asked for.
+// ear. `?debug=drop`: why the liquid drop does or does not show, readable on a
+// phone without remote dev tools. Loaded only when asked for.
 
 import type { Features } from "./features";
 
@@ -36,3 +37,17 @@ export function audioDebug(): (f: Features) => void {
     });
   };
 }
+
+/// A box of text, rewritten at most a few times a second.
+export function dropDebug(): (text: string) => void {
+  const el = document.createElement("pre");
+  el.className = "audio-debug drop-debug";
+  document.body.append(el);
+  let at = 0;
+  return (text) => {
+    const now = performance.now();
+    if (now - at < 250) return;
+    at = now;
+    el.textContent = text;
+  };
+}
diff --git a/web/src/style.css b/web/src/style.css
index 100d21e..dfabb50 100644
--- a/web/src/style.css
+++ b/web/src/style.css
@@ -482,6 +482,8 @@ button.danger:not(.link) { background: var(--accent); border: none; color: #fff;
   pointer-events: none;
 }
 
+.drop-debug { margin: 0; padding: 0.4rem 0.5rem; max-width: calc(100vw - 1.4rem); font: 10px/1.35 ui-monospace, monospace; color: #fffc; white-space: pre-wrap; }
+
 .card.paused .art { transform: scale(0.96); filter: brightness(0.7); }
 .paused-badge {
   position: absolute;
diff --git a/web/src/visual.ts b/web/src/visual.ts
index 520ee4e..1b210e3 100644
--- a/web/src/visual.ts
+++ b/web/src/visual.ts
@@ -68,6 +68,7 @@ export class Visualizer {
   private reduced = matchMedia("(prefers-reduced-motion: reduce)");
   private setting: VisualsSetting = localStorage.getItem(VISUALS_KEY) === "simple" ? "simple" : "liquid";
   private debug: ((f: Features) => void) | null = null;
+  private dropDebug: ((text: string) => void) | null = null;
   /// A press on the drop; `on` once it moved enough to turn it.
   private grab: { id: number; x: number; y: number; on: boolean } | null = null;
   private spun = false;
@@ -103,9 +104,9 @@ export class Visualizer {
       if (this.spun) e.stopPropagation();
       this.spun = false;
     }, true);
-    if (new URLSearchParams(location.search).get("debug") === "audio") {
-      import("./debug").then((m) => { this.debug = m.audioDebug(); });
-    }
+    const debug = new URLSearchParams(location.search).get("debug");
+    if (debug === "audio") import("./debug").then((m) => { this.debug = m.audioDebug(); });
+    if (debug === "drop") import("./debug").then((m) => { this.dropDebug = m.dropDebug(); this.start(); });
   }
 
   get visuals(): VisualsSetting {
@@ -529,6 +530,11 @@ export class Visualizer {
         ? this.features.fromAnalyser(an, now / 1000, dt)
         : this.features.fromLoudness(card.loudnessAt(progress), now / 1000, dt);
     this.debug?.(f);
+    this.dropDebug?.([
+      `setting ${this.setting} · reduced motion ${this.reduced.matches} · touch ${this.touch} · mixing ${mixed}`,
+      `blob ${this.blob === undefined ? "not asked" : this.blob === null ? `failed: ${LiquidBlob.failure}` : "made"} · card liquid ${!!card.el?.classList.contains("liquid")}`,
+      this.blob?.describe() ?? "",
+    ].join("\n"));
     let busy = this.shine(now, dt, f.kick) || playing;
     const liquid = !!this.blob && !!card.el?.classList.contains("liquid");
     if (!this.reduced.matches) {