Supported model formats

The following 3D and 2D model formats are supported by Castle Game Engine. They can be loaded e.g. using the TCastleScene.Load method. You can also open them in view3dscene.

1. Best formats to use

1.1. glTF 2.0

An efficient, modern format, developed by Khronos. Resources:

Supported features of glTF models in our engine:

  • Meshes (polygons, lines), transformation hierarchy.

  • Materials (with physically-based or unlit shading), alpha mode, double-sidedness, per-vertex colors.

  • Texturing (for base color, normal maps, emissive, material-roughness).

  • Cameras (perspective and orthogonal).

  • Animating transformations (position, rotation, scale) and using skin ("armature" in Blender). They can be played using standard CGE PlayAnimation method (or other means, e.g. to play multiple animations from one model simultaneously).

  • Both .glb and .gltf extensions are supported. Textures can be provided in separate files or embedded inside the GLTF stream.

  • It is integrated in our engine as X3D nodes graph. This means that you can include a glTF model inside larger X3D file using the Inline node, you can modify the glTF scene graph at runtime (e.g. modify material color, show/hide something etc.) and you can serialize the scene graph to an X3D file.

  • We use PasGLTF, a great open-source library for reading glTF by Benjamin "Bero" Rosseaux.

TODO: Main missing feature is morph targets.

1.2. Spine JSON

Spine is a powerful program for 2D game skeletal animations. Dragon Bones can also export to this format.

We have a big support for Spine JSON features, and our friendly game studio Cat-astrophe Games is using Spine for all 2D games.

1.3. X3D and VRML

X3D and VRML is a flexible and powerful format for 3D models and a basis of our scene graph.

The following extensions are recognized:

  • X3D in classic and XML encoding: .x3d, .x3dz, .x3d.gz, .x3dv, .x3dvz, .x3dv.gz

  • VRML 1.0 and 2.0: .wrl, .wrz and .wrl.gz.

We have a great support for X3D and VRML, and handle rendering, animation, interaction, scripts, shaders and more features of these formats. An entire section of this website, Scene Graph (X3D), documents all the features we support (from the X3D and VRML standard, and many of our own extensions).

1.4. Castle Animation Frames (castle-anim-frames) format

Castle Animation Frames (castle-anim-frames) format, formerly known as kanim.

This is a simple format for animations, used to export animated models from Blender. It supports animating of everything in Blender (transformations, skin, shape keys, materials, particles, physics...), although it is somewhat memory-hungry.

2. Other formats you can use

2.1. Animation through a series of static models

Animation through a series of static models like xxx000.obj, xxx001.obj, xxx002.obj....

This is useful if you have files named like:

xxx001.obj
xxx002.obj
xxx003.obj
...

You can load such animation from a sequence of files using the URL [email protected](3).obj. It's exactly how you can load a movie from a sequence of images. See demo-models/.../wavefront_obj_animation for an example, you would load them by [email protected](6).obj.

It's not an efficient way to store the animation in a file (or to load it). It is much better to export to X3D or glTF animation, if you can. But it may be useful when you have no other option to export.

Blender exporter to Wavefront OBJ with "Animation" checkbox generates such animation. Hint: uncheck "Write Normals" and check "Keep Vertex Order" in the exporting dialog box, to make sure models are "structurally equal" which allows CGE to merge the animation nicely (even produce more intermediate animation frames, if needed). This also means that CGE will recalculate normals by itself (unfortunately this isn't always desired, because Blender doesn't pass the creaseAngle information to CGE, so CGE cannot smooth the normals as in Blender -- it doesn't know when it should).

The animation is played and smoothed following the same logic as castle-anim-frames format. In a way, using URL [email protected](4).obj is just a shortcut for creating a xxx.castle-anim-frames file that would list the appropriate static frames using XML elements.

2.2. Collada

Collada (.dae extension). We support a lot of Collada features — geometry with materials, textures, cameras, lights. Tested on many Collada examples, like Collada Test Model Bank and Collada models exported from various Blender versions. All modern Collada versions (1.3, 1.4, 1.5) are handled.

Animations in Collada files are not handled yet. If you need animations, we advise to use glTF instead. glTF is newer and has similar feature set. Khronos provides a converter from Collada to glTF.

2.3. OpenInventor

OpenInventor 1.0 ASCII files (.iv extension) are handled. Inventor 1.0 and VRML 1.0 are very similar formats, we also handle some additional Inventor-specific nodes.

2.4. 3DS

3d Studio 3DS format. We support most important things: meshes, cameras, materials, textures.

2.5. MD3

MD3. This is the format used for models in Quake 3 and derivatives (Tremulous etc.). Almost everything useful from MD3 file is supported: geometry with texture (coordinates, and texture filename from associated xxx_default.skin file), animation is also read and played.

2.6. Wavefront OBJ

Wavefront OBJ files. We support most important things: geometry (with texture coords, normal vectors), materials (colors, opacity, texture filenames).

2.7. STL

STL (Standard Triangle Language, aka STereoLithography). STL is a simple popular 3D format used in 3D printing. We support both ASCII and binary formats.

2.8. Videoscape GEO

Videoscape GEO (.geo extension). Very basic support for this very old 3D format.