CC Creation Tutorial: Smooth Seams in Blender
In this tutorial, I will show you how to make your mesh seams smooth inside Blender (no Milkshape required!) and walk you through the process step by step. We will make a perfectly smooth mesh and transfer the normal data from that mesh to our main mesh using the Data Transfer modifier.
I am using Blender 3.6 in this tutorial (though you should be able to follow along using other versions as well)
You do not need to have much previous knowledge to follow this tutorial, but I assume you know some basics in Blender like how to select, things, navigate around, etc, and know how to import the meshes and put them into Blender.
For this tutorial, I exported the Sims 3 afbodyEP4DressPromBigBow mesh with TSR Workshop. You can use any clothing mesh you like though, and works on any meshes, not just Sims 3 ones.
This is our mesh. You can already tell that it has the dreaded seams on the neck and the rest of the body.
First, we need to make a copy of the mesh (in Object mode, select the mesh and hit Ctrl+D Shift+D to duplicate it, then hit Esc to stop it from moving around).
Rename the mesh (I added Seamless to the mesh name).
Make sure the original mesh is hidden (click the eye symbol) and select the Seamless mesh.
Press the Tab key to go into Edit Mode.
Now we select the parts that we want to have smooth seams. Let's select everything that is skin (you can select a litte piece of the mesh and then press Ctrl+L to select the entire piece)!
Now, press M and in the menu, choose By Distance. (in older versions, this is called Remove Doubles).
This will remove all double vertices at the seams on the selection we made.
It will show you how many vertices it removed. The skin looks nice and smooth!
Let's switch back to our original mesh: Make sure you deactivate the eye on the Seamless mesh and activate the eye again on the main mesh. Then, select the main mesh.
Now, let's add a data modifier to our main mesh. Click the blue wrench icon in the vertical list of the properties panel and then onto Add Modifier, then choose Data Transfer from the list.
As the source, we choose our Seamless mesh.
Also toggle on Face Corner Data and click the Custom Normals button.
Hold on, there is a message saying that we should enable Auto Smooth in Object Data Properties. Let's do that next! (if the message does not appear for you, maybe Auto Smooth is already on).
Click the green inverted triangle button and in the Normals section, toggle on Auto Smooth.
Now we can switch back to the modifier tab by clicking the blue wrench icon again.
But hang on, what happened to our mesh? There are now black spots over the dress and shadows on the legs!
This is due to the Data transfer modifier's Mapping setting. If we change it to Topology, our mesh goes back to normal again. Phew!
Now that the normals look good, we can start the transfer of our new smooth normals from the seamless mesh to our main mesh. To do that, we hit the Generate Data Layers button. This button works destructively, so you cannot undo what it did, just FYI.
Note: On newer versions of Blender, Generate Data Layers may not be enough to transfer the normals and you may need to apply the modifier instead.
You can toggle the modifier's visuals on and off with the little screen icon to see the results after you click Generate Data Layers to see if it stuck. If it did not (and you see the seams of your base mesh when toggling it off), try to apply it instead.
I switched from textured to solid shading because the differences are just more noticeable in this mode. This is how our mesh looks now with the modifier turned off.
Because we clicked the transfer button, the normals have been permanently applied to our mesh. The skin is smooth now, and so is the dress (even though we did not smooth that one, hmm...)
If we toggle the modifier back on, suddenly the dress has seams again! What's going on there? I'm not exactly sure why, but Auto Smooth seems to be doing some smoothing on the dress mesh as well.
I am not sure if this is normal behavior or not, but let's pretend that this did not happen and the modifier in fact did not smooth the dress.
Maybe we just forgot to smooth some areas on the Seamless mesh that we noticed only later on. That's no problem. We simply modify our Seamless mesh again!
So let's swap back to the seamless mesh and select it (remember to click the eye icons so only the Seamless mesh is visible).
Let's select the main dress parts and press M -> merge by distance on them. We cannot smooth the whole dress all at once, because then that would remove some seams that we want (like those for the backfaces and the middle section of the dress where the bow is attached).
If we remove the wrong seams, we ruin our normals and will have black splotches.
Now, let's select the backfaces and areas we left out before and repeat this process: M -> merge by distance.
Look at how perfect our Seamless mesh is looking now! Now, let's transfer those beautiful normals to our main mesh.
Select the main mesh and toggle the eye icons again, to hide our Seamless mesh and reveal our main mesh.
Once again, we will use the Generate Data Layers button in our Data Transfer modifier. If you have previously applied the modifier, just add the modifier again to the main mesh and use the settings shown here.
And that's it, you are done! You have a perfectly smoothed mesh that you can export now.
Final Note: it is best to transfer the normals at the very end of your meshing process because any action that recalculates the normals can reset our custom-made smooth normals again.
Of course, you can simply use the Generate Data Layers button again to re-add them, but it saves you time to only do this step at the end.
I almost forgot to say: You still have to use Mesh Toolkit to fix the seams on the edges of your mesh and do the usual shenanigans.
