When I view my 3D models in the Fab 3D Viewer, the wireframe view automatically quadrifies all triangles on the mesh. I have observed this behavior with all models that I have uploaded, as well as those migrated from Sketchfab. Typically, I manually triangulate my meshes because the normal map depends on this configuration. It appears that the viewer visually displays quads, but this causes the topology of some models to look unusual.
I have not yet been able to test whether the downloaded models from the store will also be quadrified (hopefully not). Is there any way to avoid this quadrification?
What type of bug are you experiencing?
UI/Tools
Steps to Reproduce
Viewing a mesh in the 3D viewer
Expected Result
The wireframe of the mesh should display the correct triangles assigned to the model.
Observed Result
The wireframe view automatically quadrifies all triangles on the mesh
Why/how is Fabs 3D viewer showing a different wireframe to what the model actually looks like?
This problem below, to my mind, is the most important part of selling a model.
I have just checked some of my models and to my horror the wireframe is different to the models I uploaded.
I, like many others, take so much care to make sure my models are a good topology and all quads, it’s shocking to see what the viewer is showing.
I wouldn’t buy a model with topology like it is showing. It wasn’t created with A.I, with the sludge like topology A.I creates, my models are created with care.
So…the first 3D view is Fabs viewer, with the terrible wireframe. The second is Sketchfabs 3D viewer.
The model is exactly the same.
Below are Screen shots I have just taken of one of my models.
Surely this can’t be just my models doing this.
If you’re still reading this and it is happening to your models please vote this up. The wireframe can make or break a sale.
On Sketchfab, we generate and load the original wireframe. In the Fab viewer, we took a different approach where we infer the quads from the processed triangle mesh. This was to reduce the amount of data downloaded by the viewer, which can be quite a lot for large meshes.
We will consider reverting back to the Sketchfab viewer approach, where the real wireframe is “lazy loaded” after the rest of the resources.
I have to add, as I’m really worried about the decision that will be made…
If the decision is to keep the Fab viewer could there be a notice/disclaimer that states…
…the wireframe shown is not a true representation of the models topology.
Also, could a link to the model on Sketchfab be made available so that anyone wishing to see what the models true topology looks like can view it there.
Lastly, will we be informed when the decision is made?
We decided to drop the generated quad wireframe, and download the original wireframe when it’s available. You should be able to see the exact topology you crafted when it’s released.
It should be available in a couple of weeks.
For you to understand the rationale behind how the feature was implemented, here are some explanations:
In sketchfab some wireframes were very heavy and were taking time / bandwidth to download (mostly for big scans or sculpts). Also it was not really lazy loaded. It was downloaded once the model was finished downloading. But we were loading it everytime for every model, and it was a waste most of the time as users don’t always display the wireframe.
Another problem is that not all uploadable formats supports quad wireframes, only fbx, obj and blend files. Gltf for example doesn’t support it.
We wanted to explore generating quads from triangulated meshes so that users could have the same experience whatever the upload format.
We had good results with the algorithm we use, however, as you noted it had some weaknesses:
There could be some shift on some edges that could make the topology look wrong.
We didn’t think of people triangulating their mesh on purpose to be perfectly honest.
There was a debate in the team whether it was an important issue or not and we ultimately decided to ship with this feature.
Well, your comments helped to close that debate.
We’re doing like in Sketchfab, but with real lazy loading this time.
