I Built a JS WebGL Engine: My 2025 Verdict Is Shocking

Introduction: The Allure of the Abyss

Every seasoned JavaScript developer has had the thought. You're working with a powerful library like Three.js or Babylon.js, and a little voice whispers, "I could build this. But... better. Leaner. Faster. Perfectly tailored to my needs." For years, I ignored that voice. I told myself it was hubris, a colossal waste of time, a path to madness. But the allure of crafting a JS WebGL engine from the ground up—of truly understanding the graphics pipeline from vertex buffer to final pixel—was too strong to resist.

So, I did it. I spent the better part of a year architecting, coding, and debugging my own 3D engine, codenamed 'Helios'. Now, in early 2025, I'm emerging from the abyss of GLSL shaders and matrix transformations to deliver my verdict. And trust me, it’s not what you think. It's a shocking revelation about performance, learning, and the future of 3D on the web.

The "Why": Genesis of a Crazy Idea

Why embark on such a seemingly redundant quest? The web is graced with mature, feature-rich, and brilliantly maintained libraries. My reasons were threefold:

1. The Black Box Problem: While I was proficient with Three.js, I felt like I was operating a complex machine without understanding its inner workings. I could make things appear on screen, but I couldn't intuitively debug performance bottlenecks or grasp why certain rendering techniques worked the way they did. I wanted to shatter the black box.
2. The Performance Obsession: For a specific project involving thousands of independently moving objects, I was hitting performance ceilings. I hypothesized that a hyper-specialized, tree-shakable engine with a minimal core could outperform a general-purpose library by shedding the weight of features I didn't need.
3. The Ultimate Learning Challenge: More than anything, I saw building a JS WebGL engine as the final frontier of my front-end development journey. It was a personal Everest, a challenge that would force me to master linear algebra, low-level APIs, and performance optimization in a way no tutorial ever could.

The Build: A Journey into the Graphics Pipeline

The process was both exhilarating and humbling. It began not with fancy 3D models, but with a single, colored triangle on a black canvas—the "Hello, World!" of graphics programming. From there, I built layer upon layer of abstraction.

Laying the Foundation: The Renderer and Scene Graph

The core of Helios is its renderer. This module is responsible for communicating with the WebGL API. It manages the WebGL context, compiles shaders, creates buffers (for vertices, indices, normals), and uploads data to the GPU. This was where I first wrestled with the verbosity of WebGL. Setting up attributes and uniforms felt like performing a complex ritual just to get data from my JavaScript code into a shader.

Next came the scene graph—a tree data structure that organizes all the objects in the 3D world. Each node in the tree has a transformation (position, rotation, scale), and these transformations are combined as you traverse down the tree. This is where the matrix math became very, very real. Debugging a `mat4.multiply()` error that results in a smeared, unrecognizable mess on screen is a unique form of character development.

Wrestling with Shaders (GLSL)

If the renderer is the engine's skeleton, shaders are its soul. Writing GLSL (OpenGL Shading Language) was a completely different paradigm. It's a C-style language that runs directly on the GPU. The vertex shader manipulates vertex positions, and the fragment shader determines the final color of each pixel. My first attempt at a simple lighting model, implementing the Blinn-Phong reflection model, took days of tweaking, reading, and debugging. But when that first light hit my 3D model, casting a specular highlight, the feeling was pure magic.

Performance is a Feature, Not an Afterthought

This was my chance to implement optimizations from the ground up. I focused heavily on minimizing draw calls, the most expensive operation in WebGL. This involved techniques like:

• Geometry Instancing: Drawing thousands of identical objects (like trees or asteroids) in a single draw call.
• Vertex Buffer Batching: Combining multiple smaller meshes into a single large vertex buffer to reduce state changes.
• Manual Memory Management: Carefully creating and reusing buffers to avoid garbage collection pauses during the render loop.

The control was immense, but so was the responsibility. One memory leak in the render loop could crash the browser tab in seconds.

The Reality Check: Custom Engine vs. The Giants

After months of work, Helios was capable. It could load models, apply textures, and implement basic lighting. But how did it stack up against the titans of the industry? I ran a series of benchmarks.

The results were sobering. While my bundle size was impressively small, my performance in standard scenarios was, at best, on par with the established engines. Their teams of brilliant engineers had already implemented nearly every optimization I could think of, and they had done it better and more robustly. My engine was fast for its specific use case, but it was brittle and lacked the vast ecosystem of loaders, helpers, and post-processing effects that make Three.js and Babylon.js so powerful for general development.

The Elephant in the Room: What About WebGPU?

Here's where we get to the truly shocking part of the verdict. As I was deep in my WebGL journey, the industry was steadily marching towards WebGPU. By 2025, WebGPU is no longer a futuristic dream; it's a stable, powerful reality in major browsers, offering lower-level access to the GPU and a more modern API design inspired by Vulkan, Metal, and DirectX 12.

Did building a WebGL engine in the age of WebGPU make my entire project obsolete? No. It did the exact opposite. It was the perfect preparation.

WebGL, with its legacy OpenGL ES 2.0 design, hides a lot of the modern GPU architecture. WebGPU exposes concepts like pipeline state objects, bind groups, and explicit command queues. Because I had built a WebGL engine from scratch—because I had wrestled with state management, data binding, and shader compilation manually—these new WebGPU concepts immediately clicked. The mental model was already there. My painful journey through WebGL's quirks had given me a deep, fundamental understanding that made the transition to the more logical, albeit verbose, WebGPU API feel like a natural evolution, not a daunting rewrite.

The 2025 Verdict: Was It Worth It?

So, was building a JS WebGL engine from scratch worth it? Yes, absolutely. But not for the reason I started.

My initial goal was to build a smaller, faster engine for production. I failed. The reality is that for 99% of projects, the performance, stability, and feature set of Three.js or Babylon.js are insurmountable. The years of community contributions, bug fixes, and edge-case handling they possess are invaluable.

The shocking truth is that the project's real value wasn't the final code. The value was the journey.

• I am now a fundamentally better graphics programmer. I can debug performance issues in *any* 3D application because I understand what's happening at the lowest levels.
• I can read the source code of Three.js and understand not just *what* it's doing, but *why* it's designed that way.
• I am uniquely positioned to leverage WebGPU to its full potential because I have a rock-solid foundation in the core principles of GPU communication.

Building my own engine didn't give me a better tool; it made me a master craftsman who can now wield any tool, including the most advanced ones, with expert precision.

Conclusion: Should *You* Build a WebGL Engine?

My advice to fellow developers is this: do not build a JS WebGL engine to replace Three.js. You won't. Instead, build one to replace the mystery. Build one to transform your understanding of how 3D graphics truly work.

• For Learning: 100% yes. It is one of the most rewarding and educational projects a web developer can undertake. Follow a guide like WebGL2Fundamentals and build from the ground up.
• For a Production App: Almost certainly no. Unless you have an extremely niche, performance-critical use case and a team of experts, you are better off leveraging the incredible work of the open-source community. Your time is better spent building your application's features on top of a stable, mature foundation.

In 2025, the best reason to build a WebGL engine is not for the destination, but for the profound and transformative journey it takes you on. It's a rite of passage that will leave you a more capable and insightful engineer, ready for whatever comes next—be it WebGL, WebGPU, or the future of the interactive web.