Pixijs Custom Rendering

If you're writing custom shaders, filters, or batchers in PixiJS v8, this covers the new dual-renderer API. The big shift is Shader.from with separate gl and gpu paths, typed UniformGroup instead of raw objects, and textures passed as resources rather than uniforms. Filters now expect GLSL ES 3.0 conventions (in/out, finalColor, texture() instead of texture2D). The UBO path is mandatory for WebGPU and needs pixi.js/unsafe-eval in strict CSP environments. Most useful when you need per-pixel effects or custom geometry rendering that built-in filters can't handle. The examples are clear enough to adapt without reading v8 migration docs first.