With the expansion of the web and the emergence of technologies like WebGL, the desire to enable interactive 3D content on websites and web applications has increased dramatically. This requires a format that can seamlessly integrate with web technologies. Many existing formats are either too large or not well-suited for real-time rendering and web delivery.
Khronos Group, a consortium of companies focused on creating open standards for the graphics and multimedia industry, developed GLTF to overcome this requirement.
GLTF, short for "GL Transmission Format," is an open standard file format for 3D graphics that is designed to be compact and efficient for transmitting and rendering 3D scenes and models.
The first mention of this file format dates back to SIGGRAPH 2012 and was originally referred to as WebGL Transmissions Format (WebGL TF), and then came into use from October 19, 2015, along with the announcement of the glTF 1.0 specification. At the moment, the 2nd version of the specification (glTF 2.0) is in use, which was released on March 3, 2017. For the purpose of this article, we will only focus on glTF 2.0.
Nowadays glTF and GLB formats are used on Sketchfab (autoconverting), Facebook (3D posts), Microsoft, Oculus, Unreal Engine and others.
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Most Popular Formats of Different Media
Binary and JSON Formats: GLTF files can be stored in two primary formats: binary (.glb) and JSON (.gltf). The binary format (.glb) is typically more compact and efficient for runtime use, while the JSON format (.gltf) is more human-readable and can be useful for debugging and editing.
Efficiency: GLTF is designed to be efficient in terms of file size and loading times. It achieves this by using techniques like data compression, texture and geometry optimizations, and a binary format that reduces file size.
Interoperability: GLTF is designed to work seamlessly with various 3D software tools, game engines, and web browsers. It is supported by a wide range of 3D modeling and animation software and has become a popular format for sharing 3D assets.
PBR Materials: GLTF supports Physically-Based Rendering (PBR) materials, which allow for more realistic and consistent rendering of materials and lighting across different platforms and applications.
Animation: GLTF can store animations, including skeletal animations and morph target animations, making it suitable for character animations and dynamic scenes.
Geometry and Scene Hierarchy: GLTF can represent complex 3D scenes with multiple objects, hierarchies, and transformations.
Texture Support: GLTF can include textures and supports various texture types, including diffuse maps, normal maps, and specular maps.
Extensions: GLTF supports extensions, which allow for additional features and custom data to be included in the format. This makes it extensible and adaptable to different use cases.
WebGL and WebVR: GLTF is well-suited for use in web applications and virtual reality (VR) experiences, as it can be easily loaded and rendered using WebGL and WebVR technologies.
Cross-Platform: GLTF is designed to be platform-agnostic, meaning that it can be used on a variety of operating systems and devices, including desktop computers, mobile devices, and augmented reality (AR) and virtual reality (VR) headsets.
Open Standard: GLTF is an open standard maintained by the Khronos Group, promoting transparency and preventing vendor lock-in. It encourages collaboration and the development of a healthy ecosystem around the format.
GLTF has gained widespread adoption in the 3D graphics and game development industries due to its efficiency and compatibility. It is commonly used for sharing 3D models on the web, in video games, virtual reality experiences, and other 3D applications.
glTF 2.0 Scene Description Structure
GLTF: Real Time Applications
GLTF (GL Transmission Format) is particularly well-suited for real-time applications in various domains due to its efficiency and versatility. The following are some commonly used real-time applications of GLTF:
Web-Based 3D Content: GLTF is widely used for creating interactive 3D content on websites and web applications. It can be loaded and rendered efficiently in web browsers using WebGL, making it ideal for web-based product configurators, e-commerce product visualization, educational simulations, and more.
Gaming: GLTF is commonly used in the gaming industry. Game engines such as Unity and Unreal Engine support GLTF, allowing game developers to use it for character models, environments, assets, and animations. Real-time rendering in games benefits from GLTF's efficiency and PBR (Physically-Based Rendering) materials support.
Virtual Reality (VR) and Augmented Reality (AR): GLTF is employed in VR and AR applications for rendering 3D objects and scenes. It enables realistic and immersive experiences by efficiently loading 3D models and animations in real-time. AR applications, in particular, use GLTF for displaying 3D objects in the real world through a mobile device's camera.
Architectural Visualization: Architects and designers use GLTF to create interactive 3D models of buildings and interior spaces. These models can be explored in real-time, providing clients and stakeholders with immersive virtual tours and visualizations of architectural designs.
Education and Training: GLTF is used in educational applications for interactive 3D simulations and training scenarios. It allows users to explore complex 3D environments and objects in real-time, enhancing learning experiences.
Product Design and Prototyping: GLTF is valuable for product design and prototyping in industries such as automotive and manufacturing. Designers can visualize and interact with 3D models of products in real-time, facilitating design reviews and iterations.
Medical and Scientific Visualization: GLTF can be used to visualize complex medical data, such as 3D scans and simulations. Real-time 3D rendering of medical models aids in diagnosis, treatment planning, and educational purposes.
Retail and E-Commerce: GLTF is used in online retail to showcase products in 3D. Customers can rotate and interact with 3D models of products, helping them make more informed purchasing decisions.
Simulations and Training: GLTF is employed in various simulation applications, including flight simulators, military training, and simulations for emergency responders. Realistic 3D models and environments are crucial for effective training.
Entertainment and Animation: GLTF can be used in real-time animation applications, such as animated storytelling and interactive experiences. It allows for the efficient display of 3D characters and scenes in real-time environments.
In these real-time applications, GLTF's compact file size, support for animations and materials, cross-platform compatibility, and ease of integration with web technologies and game engines make it a popular choice for developers and content creators aiming to deliver compelling 3D experiences to users in real-time.