MODULO PI

GLTF

Description

GLTF is a file format for 3D scenes developped and published by the Khronos Group and described on their official site as such :

glTF™ is a royalty-free specification for the efficient transmission and loading of 3D scenes and models by engines and applications.
glTF minimizes the size of 3D assets, and the runtime processing needed to unpack and use them.
glTF defines an extensible, publishing format that streamlines authoring workflows and interactive services by enabling the interoperable use of 3D content across the industry.

Export from C4D

The following parameters have been tested under version 2024.3.1 of Maxon Cinema 4D.

Materials

If your texture contains alpha the texture should be set in the Color and Alpha channels of the material.

Currently using textures in the Luminance channel breaks alpha and should be avoided.

GLTF using alpha and color channels in a C4D Material

UV Mapping

Projection should be set to UVW Mapping

Setting the Projection mode for UV Mapping in C4D for GLTF

The GLTF exporter ignores the Front / Back / Both option of the Side property.

If your texture is meant to be mapped on both sides of the mesh, you can force it by enabling the Double Sided option in the exporter settings.

Tiling

The Tile property is also ignored in the GLTF export.

Setting tiles in Cinema 4D

In Kinetic the wrap mode should be set on the corresponding material :

  • To conserve tiling, the material’s Wrap S and Wrap T should be set to Repeat (Default option)

Setting Wrap modes to Repeat in Kinetic

  • To deactivate tiling, the material’s Wrap S and Wrap T should be set to Clamp to Edge

Setting Wrap modes to Clamp to Edge in Kinetic

Animations

When using spline type key interpolations all keyframes must have the Automatic weighting option enabled. This will constrain the keyframes on the time axis to have a length of 1/3 of the time to the next keyframe in both directions.

C4D Option for Automatic Weighting

When a property (position, rotation, scale) is animated, all the X/Y/Z components must be keyframed together.

Takes

Takes are currently not supported by Cinema 4D’s GLTF exporter.

Only the animations in the Main Take will be exported in the final GLTF.

Morph Animations

Morph animations are currently not supported by Kinetic Designer.

Rotation Order

Rotation Order must be set to HBP.

Setting the rotation order to HPB in C4D for a GLTF export

Exporter options

Take care that the following options are set when exporting :

  • Bake Animation disabled (the export will resample all animations with additional keyframes)
  • Flip Z enabled

Regardless of your project scale, export your GLTF format with 1 unit for 1 meter.

GLTF export settings in Cinema 4D

Maxon’s GLTF Exporter Documentation

Kinetic guidelines

At the moment, keyframe interpolation using splines made of Bezier curves only works if the tangents are weighted to exactly 1/3 and 2/3 along the x axis between two keyframes.

Ressources

GLTF is meant to be lightweight and special care should be taken to keep polygon counts low and skeletons as simple as possible.

Here are some guidelines to keep polygon counts low in meshes.

This guide lists helpful tips when exporting to GLTF from Cinema4D

Windows 3D Viewer can be used to preview GLTF files.

Alternatively, the official Kronos GLTF Viewer can be used as a standalone viewer.

Babylon JS is another online viewer.

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