C3B File

What are C3B files and how to open them

Are you having problems opening a C3B file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your C3B files.

What is a C3B file?

A .C3B file is a Cocos2d-x 3D Object file.

Cocos2d-x's Cocos2d-x 3D Object format is a proprietary format for storing fully featured 3D model assets and their associated data for use in the Cocos2d-x game engine. It is designed for binary storage of meshes, textures, materials, skeletal animations, and other scene graph components. Developers create these files using the official fbx-conv tool, which imports standard 3D format files like FBX and exports them in this format for efficient use in applications and games. The format is good for optimizing performance in production, particularly on devices where loading speed, memory footprint, and rendering efficiency matter.

Files written in this format contain data used at runtime by Cocos2d-x, including meshes, textures, normals, UV coordinates, materials (with properties like diffuse textures and texture wrapping modes), nodes, and support for skeletal animation via a single skeleton. The engine reads these files to recreate 3D sprites or scene objects, enabling the application of actions such as animations (via Animation3D and Animate3D) and transformations. The binary format is preferred for production builds, while a corresponding text variant (with a .c3t extension) is used for debugging or version control.

Binary signature details include an initial ASCII signature of bytes "C3B\0" at the beginning of the file, and the presence within the file of keywords such as VERTEX_ATTRIB_POSITION, VERTEX_ATTRIB_NORMAL, VERTEX_ATTRIB_TEX_COORD, GL_FLOAT, MATERIAL, DIFFUSE, REPEAT, .JPG, NODE, and MESH. These strings identify parts of the data structure, including vertex attributes, material properties, texture references, mesh definitions, and node hierarchy.

How to open C3B files

Important: Different programs may use files with the C3B file extension for different purposes, so unless you are sure which format your C3B file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: August 25, 2026

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