This tutorial shows you what to do if you accidentally removed double vertices or if your creation does not have proper double vertices to begin with. I work with Blender and Milkshape. It is for somewhat advanced meshers that know the basic concepts of meshing already. Image 1: This is a mesh with edges that are properly split (has double vertices at the seams.)
Image 2: Ideally, a mesh has double vertices at a seam. This ensures that the uvmap is split properly. if I select this edge on the uvmap, only one side gets selected. The other side is connected to the other row of vertices. Every vertex has one uv coordinate. Image 3: I went and removed all double vertices for the sake of this tutorial. Notice how the vertex count went down? My creation has no sharp edges anymore, but the uvmap is still looking normal. Hey that's great, you might say. I can save vertices that way! We'll see...
Image 4: But If I try to select one edge of the uvmap, another edge gets selected with it - because they are not separated anymore. So I have two uvmap coordinates for only one set of vertices... That will cause trouble! Let's go ahead though and use this mesh like this to see what happens. Image 5: I assigned bones with the Mesh Toolkit and loaded the creation into TSR Workshop, clicking NO on the popup. The effects aren't pretty... the mesh has black areas (these are the normals that try to smoothen the mesh, because it has no defined hard edges anymore). The textures are stretched and form weird lines.
Image 6: Now let's do an experiment. Re-export that mesh out of TSR Workshop (red export button). Now open that up in Milkshape and view it in the Texture Coordinate Editor. You see that the coordinates are all connected to each other... no wonder we saw wonky textures! so how do we fix that? Well, we'll go back to our other mesh before we imported it into TSR Workshop (this mesh we just exported is beyond saving, so throw that away).
Image 7: We now use the model cleaner on our mesh. Click NO on the popup! Very important!!! No export that and reassign the bones and morphs with the Meshing toolkit.
Image 8: Now import the mesh back to TSR Workshop (remember to click NO on the first popup and yes to the second). Look, textures are all intact! The vertex count ist the same we had in blender in the first image. The model cleaner made sure there were double vertices where they had to be!
Info: I did not smooth the mesh or anything, this was just to demonstrate the effects of the model cleaner. With an actual mesh, you'd have to take the time to copy and smooth the neck seams, arms and so on, but you get the idea... :) For more tips and tricks for meshing with Milkshape and Blender, check out this tutorial!