What is glTF: A Complete Guide

GLTF (GL Transmission Format) comes into play whether you're designing an intricate 3D product configurator or building immersive virtual experiences.

This blog will break down everything you need to know about GLTF, explaining what it is, why it's important, and how it's transforming the 3D landscape.

What is glTF? 

GLTF, short for GLTransmission Format, is an open-standard file format developed by the Khronos Group.  

It's specifically designed for the efficient transmission and loading of 3D models in web applications. 

Unlike some other 3D model formats, glTF is optimized for the web, making it lightweight and fast to load, which is critical for modern digital experiences.

Key Features of glTF

Compactness

GLTF files are designed to be compact, making them ideal for web and mobile applications where loading times are crucial.

The format supports binary data storage, which means that models can be loaded quickly without sacrificing quality.

PBR Material Support

Physically Based Rendering(PBR) enables models to appear more realistic by simulating how light interacts with surfaces. 

This makes glTF a preferred choice for applications that require high visual quality, such as 3D product visualization, Virtual Reality(VR), and Augmented Reality (AR).

Cross-Platform Compatibility

glTF is highly compatible across different platforms and devices. Whether you're using a desktop, mobile device, or VR headset, GLTF files can be rendered consistently, providing a seamless user experience.

Interoperability

One of the significant advantages of glTF is its interoperability with various 3D tools and engines.

It's supported by popular platforms like Blender, Unity, and Sketchfab, making it easy to incorporate GLTF models into your workflow.

How gLTF Works

GLTF files are a collection of data describing 3D models, including their geometry, textures, and animations. There are two primary versions of GLTF files:

GLTF (.gltf)

This version uses JSON to store information about the 3D model, with separate files for geometry, materials or textures, and binary data. It's human-readable and easier to debug but involves multiple files.

GLB (.glb)

The GLB format is a binary version of glTF. It packs all the model's data into a single file, which makes it more efficient for transmission and loading. The GLB format is typically preferred for web use because of its simplicity and speed.

Applications of glTF

GLTF's versatility and efficiency make it an ideal choice for a wide range of applications across various industries. Here are some of the most impactful uses of GLTF:

3D Product Configuration

One of the most significant applications of glTF is in 3D product configurators.

These tools allow customers to configure and customize products in real-time, such as choosing different models, colors, materials, or features, and seeing those changes instantly in a 3D view. 

GLTF's lightweight and fast-loading characteristics ensure that these configurators offer a seamless, high-quality experience across all devices. 

The format's support for PBR (Physically Based Rendering) ensures that the visual representations of the products are highly realistic, which is crucial for making confident purchasing decisions.

eCommerce and Retail

Beyond product configurators, glTF is widely used in eCommerce and retail to visualize products in 3D.

Retailers can showcase their products from every angle, giving customers a more interactive and engaging shopping experience. 

This not only enhances customer satisfaction but also increases conversion rates by providing a clearer understanding of the product.

Gaming Industry 

In the gaming industry, glTF is used to create detailed 3D assets that can be easily integrated into game engines.

The format's efficiency ensures that these assets load quickly, while its support for PBR allows for high-quality, realistic visuals.

This combination makes glTF a popular choice for game developers looking to optimize performance without sacrificing quality.

Metaverse, Virtual and Augmented Reality

glTF's compact size and support for realistic rendering make it ideal for use in the metaverse, as well as in Virtual reality (VR )and Augmented reality (AR) applications.

In these immersive environments, performance and visual fidelity are crucial, and GLTF delivers on both fronts. 

This makes it easier to create convincing virtual experiences, whether for gaming, training, or marketing.

Architectural 3D Visualization

Architects and designers use GLTF to create detailed 3D models of buildings and spaces.

These models can be shared with clients or stakeholders for interactive walkthroughs, allowing them to explore and experience the design before construction begins. 

The ability to load and manipulate these models quickly is particularly valuable in presentations and collaborative settings.

3D Product Configurators and glTF

3D product configurators have become a game-changer, allowing consumers to personalize products in real-time. Here's why GLTF is the go-to format for these applications:

Efficient Web Integration

One of the main challenges with 3D content on the web is balancing quality with performance. glTF addresses this by offering a format that is both lightweight and capable of delivering high-quality visuals. ‍

This efficiency ensures that product configurators are quick to load and responsive, minimizing friction for the user.

Enhanced User Experience

The realism that glTF brings through PBR materials is vital for product configurators.

When customers can see a product in a realistic 3D environment, including how different materials and colors will look in various lighting conditions, they feel more confident in their choices. This can lead to higher conversion rates and reduced return rates.‍

Scalability

As businesses grow and expand their product lines, the ability to quickly update and scale their 3D assets becomes essential.

GLTF's interoperability with major 3D software tools simplifies this process, allowing companies to keep their configurators up-to-date with the latest products and features.‍

Future-Proofing

GLTF is designed with future advancements in mind. Its support for emerging technologies like VR and AR positions it as a future-proof format that will likely remain relevant as these technologies evolve.

glTF Extensions and Enhanced Capabilities 

Since its initial release, GLTF has continuously evolved, becoming even more versatile and powerful, thanks to various extensions introduced through a process governed by the Khronos Group.  

One of the most important aspects of GLTF is its adaptability. The format was designed with flexibility in mind, allowing it to grow and change as new technological needs arise. This is where extensions come into play.  

Core glTF Extensions

As of 2024, here are the current extensions available:

• KHR_materials_unlit: Supports unlit materials, meaning no shading or lighting is applied, which is useful for flat-shaded or cartoon-style rendering.
• KHR_materials_pbrSpecularGlossiness: Provides an alternative to the default metallic-roughness material model, using a specular-glossiness model instead.
• KHR_draco_mesh_compression: Allows for compression of mesh geometry data, reducing file sizes and improving load times, particularly in web applications.
• KHR_lights_punctual: Adds support for punctual lights (point, spot, and directional lights) in 3D scenes, enhancing realism.
• KHR_materials_clearcoat: Adds a clear coat layer on top of the material, simulating effects like automotive paint finishes.
• KHR_materials_sheen: Adds a sheen layer to materials, useful for rendering fabrics like velvet or satin.
• KHR_materials_transmission: Supports materials that simulate transparent or semi-transparent surfaces, such as glass.
• KHR_materials_volume: Enables volumetric effects within materials, such as subsurface scattering for materials like skin or wax.
• KHR_texture_transform: Allows for the transformation of textures (scaling, rotation, translation) on a material.
• KHR_mesh_quantization: Reduces the precision of mesh attribute data to save space, which is useful for optimizing models.
• KHR_texture_basisu: Allows for the use of Basis Universal compressed textures, which are highly efficient for transmission and rendering.
• KHR_materials_ior: Introduces an index of refraction property, allowing more realistic rendering of materials like glass or water.
• KHR_materials_specular: Adds specular reflection parameters to the material, giving more control over the reflective properties of surfaces.
• KHR_materials_emissive_strength: Enhances emissive materials by allowing control over the intensity of emitted light.
• KHR_mesh_gpu_instancing: Optimizes rendering by allowing multiple instances of a mesh to be drawn with a single draw call.
• KHR_animation_pointer: Facilitates the reuse of animation data across different objects or scenes.

Vendor glTF Extensions

• EXT_lights_image_based: Supports image-based lighting, allowing scenes to be lit using environment maps for more realistic lighting effects.
• EXT_texture_webp: Adds support for WebP textures, which offer better compression and quality compared to traditional formats like JPEG and PNG.
• EXT_mesh_gpu_instancing: Similar to KHR_mesh_gpu_instancing, this extension allows for efficient rendering of many instances of the same mesh.

Community glTF Extensions:

• MSFT_texture_dds: Allows for the use of DirectDraw Surface (DDS) textures, which are commonly used in game development.
• MSFT_lod: Adds support for Level of Detail (LOD), enabling models to display different versions based on the viewer's distance, improving performance.
• AGI_articulations: Allows the definition of articulated objects, which can be useful for robotics or simulations.
• AGI_stk_metadata: Adds metadata to GLTF files, often used for storing additional information relevant to specific applications.

Extensions are optional features that developers can use to enhance the functionality of GLTF files.

They can introduce new ways to compress data, add more complex animations, or even improve the realism of the 3D models.

By using these extensions, developers can tailor GLTF to suit specific needs, ensuring that it remains a cutting-edge tool for creating 3D content.‍

KHR Draco Mesh Compression GLTF Extension

A prime example of a useful GLTF extension is KHR_draco_mesh_compression.

This extension is particularly beneficial for web-based applications, including 3D product configurators, where fast load times are essential.

The KHR_draco_mesh_compression extension allows for up to a 10:1 compression ratio of mesh geometry data.

What this means in simpler terms is that it significantly reduces the size of the 3D model files without sacrificing quality.

Smaller files load faster, which is crucial for keeping users engaged on e-commerce websites.

Imagine a customer configuring a 3D model of a piece of furniture - they can make their selections and see the results almost instantly, without frustrating delays. This quick response time is essential for creating a smooth, enjoyable user experience.

At VividWorks, we understand the importance of these extensions and have fully integrated them into our 3D Product Configurator.

Supporting the KHR_draco_mesh_compression extension is just one example of how we leverage these advancements to enhance our platform's performance.

By using this extension, we ensure that our 3D models not only look great but also load quickly, providing a seamless experience for users across all devices, whether they’re on a desktop, tablet, or smartphone.

But our commitment to enhancing the GLTF experience doesn't stop there. We also support and plan to support many other extensions that add even more capabilities to the GLTF format.

For instance, in our workflow, we use an additional feature to produce precise measurement data from the 3D mesh with 3DS MAX.

The Future of glTF in 3D Product Configurators

The GLTF format is a powerful tool for creating engaging, high-performance 3D experiences across a wide range of applications, with 3D product configurators being one of its most significant uses.

Its efficiency, realism, and flexibility make it an ideal choice for businesses looking to create immersive, interactive shopping experiences that meet the high expectations of today's consumers.

The VividWorks 3D Product Configurator fully supports both GLTF and GLB formats for importing 3D model assets, utilizing GLTF 2.0's separate file format where the data is split into multiple files.

Book your free demo call today and see how we can deliver an interactive, customizable experience that enhances customer satisfaction and drives sales 🚀