Add simple performance overlay

src/music/features/musicplayer/MusicPlayer.tsx

@@ -7,12 +7,10 @@ import { musicPlayer } from "./musicPlayerSlice";
 function MusicPlayer() {
     return (
         <div className="is-flex-grow-1 is-flex is-flex-direction-column">
-            <div className="is-flex-grow-1 is-overflow-hidden">
-                <Visualizer
-                    audioContext={musicPlayer.audioContext}
-                    audioNode={musicPlayer.audioNode}
-                />
-            </div>
+            <Visualizer
+                audioContext={musicPlayer.audioContext}
+                audioNode={musicPlayer.audioNode}
+            />
             <div className="is-flex-grow-0">
                 <Controls />
             </div>

src/music/features/visualizer/Renderer.ts

@@ -11,11 +11,14 @@ class RendererError extends Error {}
 
 class Renderer {
     private canvas: HTMLCanvasElement;
+    private overlay: HTMLSpanElement;
 
     private analyser: AnalyserNode;
     private analyserData: Uint8Array;
 
-    private time: number;
+    private lastFrameTime: number;
+    private dTime: number;
+
     private buffers: {
         indices?: WebGLBuffer;
         positions?: WebGLBuffer;
@@ -26,7 +29,8 @@ class Renderer {
     constructor(
         context: AudioContext,
         node: AudioNode,
-        canvas: HTMLCanvasElement
+        canvas: HTMLCanvasElement,
+        overlay: HTMLSpanElement
     ) {
         const analyser = context.createAnalyser();
         analyser.fftSize = 2048;
@@ -34,10 +38,12 @@ class Renderer {
         node.connect(analyser);
 
         this.canvas = canvas;
+        this.overlay = overlay;
         this.analyser = analyser;
         this.analyserData = new Uint8Array(analyser.frequencyBinCount);
 
-        this.time = 0;
+        this.lastFrameTime = 0;
+        this.dTime = 0;
         this.buffers = {};
     }
 
@@ -150,7 +156,7 @@ class Renderer {
         mat4.rotateY(
             modelViewMatrix,
             modelViewMatrix,
-            this.time * ROTATION_SPEED
+            this.lastFrameTime * ROTATION_SPEED
         );
         mat4.translate(modelViewMatrix, modelViewMatrix, [-1.0, 0.0, 0.0]);
         gl.uniformMatrix4fv(
@@ -222,6 +228,8 @@ class Renderer {
         gl.vertexAttribDivisor(shader.getAttribute("aHeight"), 1);
         gl.enableVertexAttribArray(shader.getAttribute("aHeight"));
 
+        const cpuTime = Math.round(performance.now() - this.lastFrameTime);
+
         gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
         gl.drawElementsInstanced(
             gl.TRIANGLES,
@@ -231,8 +239,16 @@ class Renderer {
             this.analyser.frequencyBinCount
         );
 
+        const gpuTime = Math.round(performance.now() - this.lastFrameTime);
+
+        this.overlay.innerText = `${Math.round(
+            this.dTime
+        )}ms (${cpuTime}ms / ${gpuTime}ms)`;
+
         requestAnimationFrame((time) => {
-            this.time = time;
+            this.dTime = time - this.lastFrameTime;
+            this.lastFrameTime = time;
+
             this.drawScene(gl, shader);
         });
     }

src/music/features/visualizer/Visualizer.tsx

@@ -11,19 +11,37 @@ function Visualizer({
 }) {
     const [renderError, setRenderError] = useState<JSX.Element | null>(null);
 
-    const canvas = useCallback(
-        (canvas: HTMLCanvasElement | null) => {
+    const visualizer = useCallback(
+        (visualizer: HTMLDivElement | null) => {
             // If we're rendering an error message, we won't be
-            // setting a canvas.
+            // setting up the visualizer.
             //
             // Also, nonintuitively, renderError will be null here on
             // subsequent iterations, so we can't rely on it to
             // identify errors.
-            if (canvas === null) {
+            if (visualizer === null) {
                 return;
             }
 
-            const renderer = new Renderer(audioContext, audioNode, canvas);
+            const canvas = visualizer.children[0];
+            const overlay = visualizer.children[1];
+
+            if (
+                !(canvas instanceof HTMLCanvasElement) ||
+                !(overlay instanceof HTMLSpanElement)
+            ) {
+                throw new Error(
+                    "react did not create our visualizer div correctly"
+                );
+            }
+
+            const renderer = new Renderer(
+                audioContext,
+                audioNode,
+                canvas,
+                overlay
+            );
+
             try {
                 renderer.initializeScene();
             } catch (error) {
@@ -78,7 +96,18 @@ function Visualizer({
     );
 
     if (renderError === null) {
-        return <canvas ref={canvas} style={{ display: "block" }}></canvas>;
+        return (
+            <div
+                ref={visualizer}
+                className="is-flex-grow-1 is-clipped is-relative"
+            >
+                <canvas style={{ display: "block" }}></canvas>
+                <span
+                    className="is-bottom-left"
+                    style={{ display: "relative" }}
+                ></span>
+            </div>
+        );
     } else {
         return renderError;
     }

src/music/music.scss

@@ -3,6 +3,12 @@ $fa-font-path: "npm:@fortawesome/fontawesome-free/webfonts";
 @import "~/node_modules/@fortawesome/fontawesome-free/scss/fontawesome";
 @import "~/node_modules/@fortawesome/fontawesome-free/scss/solid";
 
-.is-overflow-hidden {
-  overflow: hidden !important;
+.is-relative {
+  position: relative !important;
+}
+
+.is-bottom-left {
+  bottom: 0;
+  left: 0;
+  position: absolute !important;
 }