Sketchfab => Blender =>Unreal Engine

By: Melvin He, Spring 2023

Overview

Exporting Exporting textures and models to other programs is a big benefit of Blender. Render

However, one issue that is regularly encountered, is that not all of the materials are translated over correctly in the new program. Baking is a solution to this issue! Texture baking takes the current state of a material overlaid on an item, and exports it as an image, usuable for materials on other programs. It's far less dynamic, and if you want to change it you'll need to come back to Blender and remake it, but it allows things to translate over correctly. Here's what I mean:

Installation

To install the addon, just download the sketchfab-x-y-z.zip file attached to the latest release, and install it as a regular blender addon (User Preferences -> Addons -> Install from file).

After installing the addon, two optional settings are available:

• Download history: path to a .csv file used to keep track of your downloads and model licenses

• Download directory: use this directory for temporary downloads (thumbnails and models). By default, OS specific temporary paths are used, but you can set this to a different directory if you encounter errors linked to write access.

Note to Blender 2.79 OSX/Linux users: The addon uses an embedded version of the SSL library. Do not hesitate to report an issue if you encounter any issue related to SSL.

Login

After installation, the addon is available in the 3D view in the tab 'Sketchfab' in the Properties panel (shortcut N) for Blender 2.80 and after, and in the Tools panel (shortcut T) for Blender 2.79.

Login (mandatory to import or export models) can be achieved through using the email and password associated to your Sketchfab account, or by using your API token, available in the settings of your Sketchfab account:

Your Sketchfab username should then be displayed upon successful login, and you will gain access to the full import and export capabilities of the addon.

Please note that your login credentials are stored in a temporary file on your local machine (to automatically log you in when starting Blender). You can clear it by simply logging out of your Sketchfab account through the Log Out button.

Organization members

If you are a member of a Sketchfab organization, you will be able to select the organization you belong to in the "Sketchfab for Teams" dropdown. Doing so will allow you to browse, import and export models from and to specific projects within your organization.

Import a model from Sketchfab

Once logged in, you should be able to easily import any downloadable model from Sketchfab.

To do so, run a search query and adapt the search options in the Search filters menu. The dropdown located above the search bar lets you specify the type of models you are browsing through:

• All site : downloadable models available under Creative Commons licenses on sketchfab.com

• Own models: PRO users can directly download models they have uploaded to their account

• Store purchases: models you have purchased on the Sketchfab Store

• Organization members can specify a specific project to browse

Clicking the Search Results thumbnail allows to navigate through the search results, and selecting a thumbnail gives you details before import:

If this fits your usecase better, you can also select the "Import from url" option to import a downloadable model through its full url, formatted as "http://sketchfab.com/3d-models/model-name-XXXX" or "https://sketchfab.com/orgs/OrgName/3d-models/model-name-XXXX" for organizations' models:

Export a model to Sketchfab

You can choose to either export the currently selected model(s) or all visible models, and set some model properties, such as its title, description and tags.

You can also choose to keep the exported model as a draft (unchecking the checkbox will directly publish the model), but only PRO users can set their models as Private, and optionnaly protect them with a password.

Finally, an option is given to reupload a model by specifying the model's full url, formatted as "http://sketchfab.com/3d-models/model-name-XXXX" (or "https://sketchfab.com/orgs/OrgName/3d-models/model-name-XXXX" for organizations' models). Make sure to double check the model link you are reuploading to before proceeding.

A note on material support

Not all Blender materials and shaders will get correctly exported to Sketchfab. As a rule of thumb, avoid complex node graphs and don't use "transformative" nodes (Gradient, ColorRamp, Multiply, MixShader...) to improve the chances of your material being correctly parsed on Sketchfab.

The best material support comes with the Principled BSDF node, having either parameters or image textures plugged into the following channels:

• Base Color

• Roughness

• Metallic

• Normal map

• Alpha

• Emission

Note that Opacity and Backface Culling parameters should be set in the Options tab of the material's Properties panel in order to be directly activated in Sketchfab's 3D settings.

Here is an example of a compatible node graph with backface culling and alpha mode correctly set (Blender 2.80 - Eevee renderer):

Known Issues

If none of the following description matches your problem, please feel free to report an issue.

Animation (import and export)

Although simple skeletal or keyframed animations should work fine, more complex animations could cause unexpected behaviour.

There is no "quick fix" for those kinds of behaviours, which are actively being worked on on our side.

Import

Here is a list of known issues on import, as well as some possible fixes.

Please note that the materials are being converted from Sketchfab to Cycles in Blender 2.79, and Eevee in Blender 2.80. If a material looks wrong, using the Node editor could therefore help you fixing possible issues.

Mesh not parented to armature

Until Blender 3.0, rigged meshes did not get parented correctly to their respective armatures, resulting in non-rigged models. This behaviour is fixed by using the plugin with a version of Blender after 3.0.

Empty scene after import

Scale can vary a lot between different models, and models origins are not always correctly centered. As imported models are be selected after import, you can try to scale them in order to make them visible (most often, the model will need to be scaled down).

If it's not enough, try to select a mesh in the Outliner view and use numpad '.' (View to selected operator) to center the view on it. Modifying the range of the clip ("Clip start" and "Clip end") in the "View" tab of the Tools panel can also help for models with high scale.

Unexpected colors (vertex colors)

If your model displays strange color artifacts which don't seem to be caused by textures, you can try checking the model's vertex colors information (Properties area -> Object data tab -> Vertex Colors layer), and delete the data if present.

Vertex colors are indeed always exported in glTF files (to allow edition), and always loaded in Blender. It is possible that this data is corrupted or useless - but disabled on Sketchfab - explaining why the online render looked fine.

Export

Transparency

Some transparency settings might not be processed correctly, and just using a Transparent BSDF shader or linking a texture to the Alpha input of a Principled BSDF node might not be sufficient: try to set the opacity settings in the Properties Panel of the Node editor, under the Options tab by setting the Blend Mode to Alpha Clip or Alpha Blend.

High Resolution textures

In some very specific cases, the processing of your model can crash due to "heavy" textures.

If your model does not process correctly in Sketchfab and that you are using multiple high resolution textures (for instance materials with 16k textures or multiple 8k textures), you can either try to reduce the original images size or upload your model without texture and add them later in Sketchfab's 3D settings.

Texture Colorspace

As of now, textures colorspace set in Blender are not automatically converted to Sketchfab, and although normal maps, roughness, metalness and occlusion textures should be processed correctly, setting a diffuse texture's colorspace in Blender as "Non-Color Data" or a metalness map as "Color" (sRGB in 2.80) will be ignored.