PixiJS autoDetectRenderer inconsistency between WebGL1 and Canvas fallback

Documented fallback priority

PixiJS’s autoDetectRenderer (and the detection used by Application) follows a fixed priority list: first try WebGL2, if unavailable try WebGL1, and finally fall back to the Canvas renderer. This order is defined in the source code and is not configurable via the auto‑detect API.

Why the fallback matters for tests

In headless CI or browsers with limited GPU support the WebGL1 context may fail silently, causing the detector to skip to Canvas. Because the choice depends on runtime WebGL support detection, the same test suite can see different renderers across environments, leading to flaky assertions about shader precision or performance.

Forcing a specific renderer in integration tests

To obtain deterministic behavior you must bypass the auto‑detect logic and instantiate the renderer (or Application) with an explicit preference.

PixiJS v6/v7 (autoDetectRenderer with force flags)

import { autoDetectRenderer } from 'pixi.js';

// Force WebGL1 (will throw if WebGL not supported)
const renderer = autoDetectRenderer({ width: 800, height: 600, forceWebGL: true });

// Force Canvas (always works)
const canvasRenderer = autoDetectRenderer({ width: 800, height: 600, forceCanvas: true });

After creation verify the choice:

console.log(renderer.type); // PIXI.RENDERER_TYPE.WEBGL or PIXI.RENDERER_TYPE.CANVAS

PixiJS v8+ (Application preference)

import { Application } from 'pixi.js';

// Force WebGL (will error if unavailable)
const app = new Application({ width: 800, height: 600, preference: 'webgl', backgroundColor: 0x1099bb });

// Force Canvas
const canvasApp = new Application({ width: 800, height: 600, preference: 'canvas', backgroundColor: 0x1099bb });

Check the active renderer:

console.log(app.renderer.type); // same constants as above

Verification steps for CI

1. Log PIXI.VERSION at the start of each test run.
2. After creating the renderer/Application, log renderer.type or app.renderer.type.
3. Run the test suite twice – once with the WebGL‑forcing option and once with the Canvas‑forcing option – and confirm the logged type matches the expectation.
4. If you need to observe the auto‑detect fall‑through, temporarily delete the force/preference flags and run in a headless environment; the log will show the switch from WebGL1 to Canvas when WebGL1 creation fails.

Note: forcing WebGL in an environment without GPU support will throw an error; therefore your test setup should first verify PIXI.utils.isWebGLSupported() (or try/catch) before forcing.

Please confirm which PixiJS version you are using (v6/v7 or v8+) so I can confirm the exact forcing syntax.