core: manual buffer sync with sync-rows, reuse unchanged buffers and pipelines across activations

Also lets the screenshot suite point at another reference directory and settle longer.

Amp-Thread-ID: https://ampcode.com/threads/T-01a0b2dd-db32-712d-99ce-12ce4a86d979
Co-authored-by: Heaust Azure <heaust.azure@gmail.com>

addons/handles/src/ComputePass.ts

@@ -4,7 +4,7 @@ export type GraphBuffer = {
   id: string;
   array: string;
   usage?: string[];
-  sync?: "frame" | "loadout";
+  sync?: "frame" | "manual";
 };
 
 export type GraphTexture = {

addons/handles/src/Scene.ts

@@ -990,6 +990,7 @@ export class Scene {
       this.#geometry.get(geometry) ??
       this.#geometry.set(geometry, new Map()).get(geometry)!
     ).set(kind, data);
+    await this.core.syncRows(name, 0, rowCount);
     if (updateGraph) await this.updateRenderGraph();
   }
 
@@ -1248,7 +1249,7 @@ export class Scene {
           id: vertex,
           array: `geometry.${mesh.geometryId}.positions`,
           usage: ["vertex"],
-          sync: "loadout",
+          sync: "manual",
         });
         const normal = `geometry-${mesh.geometryId}-normals`;
         const uv = `geometry-${mesh.geometryId}-uvs`;
@@ -1272,7 +1273,7 @@ export class Scene {
               id,
               array: `geometry.${mesh.geometryId}.${kind}`,
               usage: ["vertex"],
-              sync: "loadout",
+              sync: "manual",
             });
         const indexed = mesh.indexCount > 0;
         if (indexed)
@@ -1280,7 +1281,7 @@ export class Scene {
             id: `geometry-${mesh.geometryId}-indices`,
             array: `geometry.${mesh.geometryId}.indices`,
             usage: ["index"],
-            sync: "loadout",
+            sync: "manual",
           });
         const draws =
           indexed && mesh.faceMaterials.size

addons/handles/test/core-mock.ts

@@ -184,6 +184,10 @@ export class YawnCore {
     return Promise.resolve();
   }
 
+  syncRows() {
+    return Promise.resolve();
+  }
+
   array(name: string) {
     const rows = this.#arrays.get(name);
     if (!rows) throw new Error(`UNKNOWN_ARRAY: ${name}`);

addons/handles/test/screenshots/README.md

@@ -9,6 +9,11 @@ uses headed Chromium on a private Xvfb display and SwiftShader WebGPU at a fixed
 The first run downloads roughly 215 MB of GLBs into
 `~/.cache/yawn/gltf-sample-models`. Set `YAWN_GLTF_FIXTURES` to use another
 cache directory, or `YAWN_SCREENSHOT_MODELS=Box,BoomBox` to run a subset.
+`YAWN_SCREENSHOT_BASELINES` points at another reference directory (for example
+one captured from a known-good commit on a machine whose software renderer does
+not match the reviewed references), and `YAWN_SCREENSHOT_SETTLE_MS` (default
+1200) is how long the viewer gets to settle after the model loads before the
+capture; raise it on slow software renderers.
 Failed full-size captures and visual diffs are written to `output/`.
 
 To intentionally replace references after reviewing full-size renders, run:

addons/handles/test/screenshots/run.mjs

@@ -25,7 +25,10 @@ import { promisify } from "node:util";
 const execute = promisify(execFile);
 const directory = dirname(fileURLToPath(import.meta.url));
 const root = resolve(directory, "../../../..");
-const baselines = join(directory, "baselines");
+const baselines = resolve(
+  process.env.YAWN_SCREENSHOT_BASELINES ?? join(directory, "baselines"),
+);
+const settleMilliseconds = Number(process.env.YAWN_SCREENSHOT_SETTLE_MS ?? 1200);
 const output = resolve(
   process.env.YAWN_SCREENSHOT_OUTPUT ?? join(directory, "output"),
 );
@@ -44,7 +47,7 @@ const update = process.env.UPDATE_SCREENSHOTS === "1";
 const session = `yawn-gltf-screenshots-${process.pid}`;
 const temporary = await mkdtemp(join(tmpdir(), "yawn-gltf-screenshots-"));
 const imageSize = { width: 250, height: 180 };
-const allModels = (await readdir(baselines))
+const allModels = (await readdir(join(directory, "baselines")))
   .filter((name) => name.endsWith(".png") && name !== "initial.png")
   .map((name) => basename(name, ".png"))
   .sort()
@@ -366,7 +369,7 @@ for (const model of models) {
         );
         await browser("upload", "#file-picker", model.path);
         await browser("wait", "--fn", "window.__yawnScreenshotReady === true");
-        await browser("wait", "1200");
+        await browser("wait", String(settleMilliseconds));
 
         const state = await browser(
           "eval",