From 241c7eec0cd379b8a33e82e65b5abbe418daf01a Mon Sep 17 00:00:00 2001
From: Chris Duncan <chris@zoso.dev>
Date: Thu, 12 Dec 2024 15:50:51 -0800
Subject: [PATCH] Try async readPixels from MDN.

---
 src/lib/workers/pow.ts | 82 +++++++++++++++++++++++++++++++-----------
 1 file changed, 62 insertions(+), 20 deletions(-)

diff --git a/src/lib/workers/pow.ts b/src/lib/workers/pow.ts
index b71370e..6425937 100644
--- a/src/lib/workers/pow.ts
+++ b/src/lib/workers/pow.ts
@@ -43,6 +43,47 @@ export class Pow {
 		return out
 	}
 
+	static clientWaitAsync (gl: any, sync: any, flags: any, interval_ms: any): Promise<void> {
+		return new Promise((resolve, reject) => {
+			function test () {
+				const res = gl.clientWaitSync(sync, flags, 0)
+				if (res === gl.WAIT_FAILED) {
+					reject()
+					return
+				}
+				if (res === gl.TIMEOUT_EXPIRED) {
+					setTimeout(test, interval_ms)
+					return
+				}
+				resolve()
+			}
+			test()
+		})
+	}
+
+	static async readPixelsAsync (x: any, y: any, w: any, h: any, format: any, type: any, dest: any) {
+		if (this.gl == null) throw new Error('webgl2_required')
+		const buf = this.gl.createBuffer()
+		this.gl.bindBuffer(this.gl.PIXEL_PACK_BUFFER, buf)
+		this.gl.bufferData(this.gl.PIXEL_PACK_BUFFER, dest.byteLength, this.gl.STREAM_READ)
+		this.gl.readPixels(x, y, w, h, format, type, 0)
+		this.gl.bindBuffer(this.gl.PIXEL_PACK_BUFFER, null)
+
+		const sync = this.gl.fenceSync(this.gl.SYNC_GPU_COMMANDS_COMPLETE, 0)
+		this.gl.flush()
+
+		await this.clientWaitAsync(this.gl, sync, 0, 1)
+		this.gl.deleteSync(sync)
+
+		this.gl.bindBuffer(this.gl.PIXEL_PACK_BUFFER, buf)
+		this.gl.getBufferSubData(this.gl.PIXEL_PACK_BUFFER, 0, dest)
+		this.gl.bindBuffer(this.gl.PIXEL_PACK_BUFFER, null)
+
+		this.gl.deleteBuffer(buf)
+		return dest
+	}
+
+
 	static calculate (hashHex: string, threshold: number | string = '0xFFFFFFF8', callback: (nonce: string | PromiseLike<string>) => any): void {
 		console.log(`start calculate: ${performance.now()}`)
 		if (typeof threshold === 'number') threshold = '0x' + threshold.toString(16)
@@ -300,27 +341,28 @@ export class Pow {
 			this.gl.clear(this.gl.COLOR_BUFFER_BIT)
 			this.gl.drawArrays(this.gl.TRIANGLES, 0, 6)
 			const pixels = new Uint8Array(this.gl.drawingBufferWidth * this.gl.drawingBufferHeight * 4)
-
-			this.gl.readPixels(0, 0, this.gl.drawingBufferWidth, this.gl.drawingBufferHeight, this.gl.RGBA, this.gl.UNSIGNED_BYTE, pixels)
-
-			// Check the pixels for any success
-			for (let i = pixels.length - 4; i >= 0; i -= 4) {
-				if (pixels[i] !== 0) {
+			// this.gl.readPixels(0, 0, this.gl.drawingBufferWidth, this.gl.drawingBufferHeight, this.gl.RGBA, this.gl.UNSIGNED_BYTE, pixels)
+			this.readPixelsAsync(0, 0, this.gl.drawingBufferWidth, this.gl.drawingBufferHeight, this.gl.RGBA, this.gl.UNSIGNED_BYTE, pixels)
+				.then(pixels => {
+					// Check the pixels for any success
+					for (let i = pixels.length - 4; i >= 0; i -= 4) {
+						if (pixels[i] !== 0) {
+							console.log(`frame time: ${performance.now() - start}`)
+							const hex = this.hexify(this.work1) + this.hexify([
+								pixels[i + 2],
+								pixels[i + 3],
+								this.work0[2] ^ (pixels[i] - 1),
+								this.work0[3] ^ (pixels[i + 1] - 1)
+							])
+							// Return the work value with the custom bits
+							typeof callback === 'function' && callback(hex)
+							return
+						}
+					}
 					console.log(`frame time: ${performance.now() - start}`)
-					const hex = this.hexify(this.work1) + this.hexify([
-						pixels[i + 2],
-						pixels[i + 3],
-						this.work0[2] ^ (pixels[i] - 1),
-						this.work0[3] ^ (pixels[i + 1] - 1)
-					])
-					// Return the work value with the custom bits
-					typeof callback === 'function' && callback(hex)
-					return
-				}
-			}
-			console.log(`frame time: ${performance.now() - start}`)
-			// Nothing found yet, try again
-			self.requestAnimationFrame(draw)
+					// Nothing found yet, try again
+					self.requestAnimationFrame(draw)
+				})
 		}
 
 		// Begin generation
-- 
2.34.1