WebGL- és 3D-élmények

WebGL & 3D Experiences

Use WebGL, custom shaders, or 3D scenes only when spatial depth, interactive 3D inspection, or shader-driven visual effects deliver clear product value that CSS, SVG, or 2D Canvas cannot achieve at a fraction of the bundle and GPU cost.

Justification & Progressive Enhancement Gate

Before introducing Three.js or a custom WebGL pipeline:

1. Bundle & initialization budget: Lazy-load 3D libraries (await import('three')) behind an IntersectionObserver or route split so initial page load (LCP / TTI) is never blocked by a 150KB+ 3D engine.
2. Capability & fallback check: Gracefully handle missing WebGL contexts, software renderers, low-power devices, and prefers-reduced-motion: reduce by rendering a crisp static image, SVG, or CSS gradient fallback underneath the canvas.
3. On-demand rendering (frameloop="demand"): If the 3D scene only changes when the user drags, hovers, or scrolls, render on demand rather than running a continuous 60fps requestAnimationFrame loop that drains laptop and mobile batteries.

Performance & Fill-Rate Guardrails

• Clamp pixel ratio (Math.min(window.devicePixelRatio, 2)): Rendering a full-viewport fragment shader or 3D scene at devicePixelRatio = 3 or 4 multiplies pixel fill-rate cost by $9\times$–$16\times$ with negligible visual gain and severe thermal throttling.
• Shader & draw-call discipline:
  • Keep draw calls low by merging static geometries or using InstancedMesh for repeated elements.
  • Pre-compile materials and avoid dynamic shader recompilation during user interaction.
  • Keep DOM overlays (text, buttons, tooltips) in standard HTML/CSS above the <canvas> (pointer-events: none on the canvas unless dragging) rather than rendering UI text as 3D textures.

Context Loss & Complete GPU Memory Disposal

Browsers evict WebGL contexts when background tabs accumulate or GPU memory is pressured, and SPA navigation leaks GPU VRAM if resources are not explicitly freed:

// 1. Handle WebGL context loss & restoration without crashing the page
canvas.addEventListener('webglcontextlost', (e) => {
  e.preventDefault(); // Allows context to be restored later
  renderer.setAnimationLoop(null);
});
canvas.addEventListener('webglcontextrestored', () => {
  initSceneResources();
  renderer.setAnimationLoop(animate);
});

// 2. Complete GPU resource disposal on component unmount
function disposeThreeScene(scene: THREE.Scene, renderer: THREE.WebGLRenderer) {
  renderer.setAnimationLoop(null);
  scene.traverse((obj) => {
    if ((obj as THREE.Mesh).isMesh || (obj as THREE.Line).isLine) {
      const mesh = obj as THREE.Mesh;
      mesh.geometry?.dispose();
      const materials = Array.isArray(mesh.material) ? mesh.material : [mesh.material];
      for (const mat of materials) {
        if (!mat) continue;
        for (const value of Object.values(mat)) {
          if (value && typeof (value as THREE.Texture).dispose === 'function') {
            (value as THREE.Texture).dispose();
          }
        }
        mat.dispose();
      }
    }
  });
  renderer.dispose();
}