Quick answer: A scroll-driven 3D website is built by rendering a Three.js scene on a fixed canvas behind your HTML content, then using GSAP’s ScrollTrigger plugin to sync the scene’s camera position, object transforms, and material effects to the user’s scroll progress. As the user scrolls, ScrollTrigger reports a progress value (0 to 1) that drives the 3D animation in real time — turning ordinary scrolling into a cinematic, choreographed experience. A solid first build typically takes 16-40+ hours depending on complexity.
If you’ve landed on a site where scrolling feels like watching a movie — camera moves, objects morphing, lighting shifting — that effect almost always comes from one specific technical combination. Here’s exactly how it works.
The Core Technique: Progress-Driven Animation
The fundamental mechanic is simpler than it looks. For each section of the page, a GSAP ScrollTrigger instance is created, and it reports a “progress” value on an onUpdate callback, where 0 is the start of the section, 0.5 is the middle, and 1 is the end — that progress number is then used to drive the Three.js scene. Firebase
The Three.js canvas itself sits independently from the scrollable content: Three.js is initialized so its canvas is fixed and positioned behind all the HTML content, staying visible on screen at all times, while the scene updates based on each section’s scroll progress inside the render loop. Firebase
The Build Process, Step by Step
A widely-used practical breakdown of this workflow looks like this: set up the Three.js scene as usual, add the GSAP and ScrollTrigger npm packages, define a master GSAP timeline with tweens for camera position, mesh transforms, and material uniforms, wrap that timeline in a ScrollTrigger with scrub set to true so scroll directly scrubs the timeline, add Lenis for smooth scroll feel, then test thoroughly on mobile since scroll-driven sites can feel sluggish without real optimization work. Medium
For asset-based projects specifically, the flow typically runs: scaffold the project (commonly Vite + Three.js), get a basic scene rendering with camera, light, and geometry, load the actual 3D asset as a glTF file, hook up the animation timeline using GSAP or Three’s built-in animation system, add interactivity for clicks and scroll, optimize for mobile with device-tier checks and asset compression, then deploy. Medium
Smooth Scrolling: The Detail That Makes It Feel Premium
Native browser scroll feels noticeably rougher than what you see on award-winning 3D sites. The fix is a smooth-scroll library paired directly into the render loop: a smooth-scroll library like Lenis is initialized, its scroll event is wired to update ScrollTrigger, and then GSAP’s own ticker drives both the Lenis raf loop and the Three.js renderer on every tick — GSAP ends up driving everything through its ticker, Lenis updates the scroll feel, and the scene renders on each frame. 200oksolutions
Beyond Simple Scrubbing: Pinning and Scene Transitions
More advanced scroll-driven sites don’t just move a camera — they pin sections in place while a full scene transition plays out. One real implementation pattern: a GSAP timeline is set up with ScrollTrigger configured to pin a hero section in place while scrubbing, then chains multiple animations together — text blurring and fading out, camera pulling back and reframing the scene — so the pinned section feels like a cinematic sequence rather than a plain scroll. 200oksolutions
For a deeper hands-on build, a recent published tutorial from Codrops walks through combining several of these techniques at once: syncing WebGL and the DOM so Three.js planes perfectly match HTML image positions, smooth scrolling that plays nicely with a render loop, and scroll-triggered shader animation that reveals images as they enter the viewport. The full walkthrough is available in Codrops’ scroll-revealed WebGL gallery tutorial, which is one of the most detailed public resources on this exact technique. Wix
An Alternative Technique: Image Sequences
Not every scroll-driven 3D effect is a live-rendered scene. Many of the most famous examples (including Apple’s product pages) actually use a different, lighter-weight approach: the effect is powered by GSAP plus ScrollTrigger and a numbered sequence of images rendered to a canvas — as the user scrolls, the animation scrubs through frame numbers and draws the corresponding image, creating the illusion of a real-time 3D render without the GPU cost. Medium
This comes with real best practices worth following: place this lower on the page rather than in the hero, so there’s time to preload the image sequence and the first view isn’t a blank canvas; never scroll-jack — let native scroll drive the scrub instead of overriding it; and add a fallback for slower devices and small screens, similar to how major brands serve a static image on mobile instead of the full sequence. Medium
Cleanup: The Part Most Tutorials Skip
This matters enormously for any site with page transitions or a single-page app structure, and it’s the detail that separates a demo from a production-ready build. GSAP plugins like ScrollTrigger and SplitText create instances and DOM wrappers that don’t automatically disappear when a page changes, so triggers and tweens need to be killed and SplitText reverted before leaving a route, then re-initialized after entering the next one. Wix
The same discipline applies to the 3D layer itself: removing a mesh from the scene isn’t enough — if WebGL objects are recreated per page, geometries, materials, and textures for unused assets need to be explicitly disposed of, or GPU memory will creep up after multiple page transitions. Wix
What This Actually Costs in Time and Money
Realistic expectations matter here, since this style of build is genuinely more involved than a standard website. A first scroll-driven 3D build typically takes 16-40 hours, and for a personal portfolio, self-learning the whole stack is feasible with effort — but for a commercial site with real deadlines and conversion goals, self-learning to commercial-quality 3D work can take 6-12 months, which usually makes hiring an experienced developer the more practical route. Medium
This tracks with what we’ve found scoping real client projects — a properly planned scroll-driven 3D site is a multi-week engagement, not a quick add-on, once you factor in asset preparation, performance optimization across devices, and the animation choreography itself.
Performance: Don’t Skip This for the Sake of the Effect
A visually stunning 3D scroll site that performs badly defeats its own purpose — poor Core Web Vitals scores directly hurt both user experience and search visibility, something we cover in full in our Core Web Vitals 2026 guide. Test on real mid-range mobile devices early, not just on a development machine, since 3D rendering performance varies dramatically across hardware.
Frequently Asked Questions
Do I need to know Three.js and GSAP both, or is one enough?
Both, for a true scroll-driven 3D effect. Three.js renders the 3D scene; GSAP’s ScrollTrigger drives that scene’s state based on scroll position. They’re complementary tools solving different halves of the problem.
Is an image-sequence approach easier than a live 3D render?
Generally yes, and it’s lighter on GPU resources — it’s how many large-scale product sites achieve a “3D” feel without real-time rendering overhead, at the cost of losing true interactivity.
How long does it realistically take to build one of these sites?
A first build for a portfolio project runs roughly 16-40 hours. A polished, production-ready commercial site with multiple scenes and full mobile optimization typically takes several weeks.
Will a scroll-driven 3D site hurt my Core Web Vitals scores?
It can, if not optimized carefully — asset compression, lazy loading of 3D assets below the fold, and proper WebGL memory cleanup are essential to keep loading speed and responsiveness in good standing.
Can this be built as a single-page site, or does it work with multi-page navigation too?
Both are possible, but multi-page setups require extra care — ScrollTrigger instances and WebGL resources must be properly disposed of between page transitions to avoid memory leaks and lingering animations.
For how a project like this fits into overall budgeting, see our complete website development cost guide.
Want a scroll-driven 3D experience built for your brand? Contact us with your reference sites and goals for a scoped quote.