Unwrapping UVs

This doc goes over how to Unwrap UVs in regards to Trim Sheet textures...

With the main texture imported, even if it is just the Diffuse texture, we can start unwrapping the UVs in order to tell which colors go on which polygons. In the case of unwrapping UVs, we are actually telling which polygons to go on which colors.

The UV Editing layout has two main windows. The UV Editor on the left, and the standard 3D Viewport on the right.

• Select the 'UV Editing' tab at the top of Blender.

• Go into 'Edit' Mode on the asset and select some of the polygons. Notice how shapes will appear in the UV Editor.

The shapes in the UV Editor represent the polygons of your 3D asset. The goal is to get these shapes into their respective colors on the Diffuse texture.

• Select all the polygons in the 3D Viewport.

  • Left click, Left drag, and/or [Shift] to multiselect.

  • Use X-Ray mode or [Alt + Z] to select through objects.

Editing the UVs

As Trim Sheets have many different approaches to how to apply the UVs we can look at the most common that were not covered in previous tutorials.

Smart UV Project

Smart UV Project will take all the polygons and flatten them to the UV as best as it can. You can adjust some of the setting to do so before applying it, but the default settings are usually pretty good to get started.

• Select 'UV > Smart UV Project' in order to flatten your asset UVs.

• Select 'Unwrap' on the popup.

You will notice that all the selected polygons will be placed within the UVMap according to the properties you set. You could then take these UVs and move them around the texture as needed. Depending on the complexity of your asset this may be enough.

Unwrapping with Seams

A common approach is by adding seams to the asset and then unwrapping the UVs from that. Much like seams of clothes, if you pull apart the clothes from the seams all the pieces would be able to be completely flat.

Flat objects like crates a relatively easy to figure out where the Seams should be, organic objects like characters or animals are a little more complicated, but with practice this becomes quite clear.

One thing to not is that seams do usually break the appearance of the texture, make sure to add seams at locations that are less obvious, or make sense if the texture changes abruptly.

• In the 3D Viewport in 'Edit Mode', select the edges that you would like to have a seam.

• Right click and select 'Mark Seam'.

• Use 'Clear Seam' if you want to remove the seam.

• Select 'UV Menu > Unwrap' to flatten your Asset with the seams.

Blender may not be able to flatten the asset as it is trying to make everything flat, which may warp some of the polygons. Continue adding Seams in order to break up any elements that may be distorting the result.

Selecting Elements within the UV Editor

Sometimes it is difficult to tell which polygons, edges, or Vertices are which UVs. Blender has an option that allows you to select both at the same time.

• At the top left of the UV Editor viewport, select the 'UV Sync Selection'.

• What you select in the UV Editor will also be selected in the 3D Viewport.

This is very useful if you are trying to clean up seams but can't find the exact edges from the 3D Viewport alone. Switch between UV Sync and Standard selection as needed.

Project from View

In some cases, such as flat surfaces, you may be able to get away with projecting from view. Note that if the polygons are flat to the view, the texture will stretch across this polygon, in some cases this actually may be useful, but in most cases it is not, at least for this type of Asset Creation.

• Change the viewport to the direction you want the UVs to go. The top, side or front of the Crate for example.

• Select 'UV" menu > Project from view'.

  • This flattens the UVs onto the UV Map to the view.

• Adjust the UVs to the location on the texture you would like.

Tiling the Asset

In many situations you can use a tileable texture that tiles at the edges of the texture to repeat the texture indefinitely by scaling the UVs over the edges of the UV Map. In some cases, you may want part of the tileable textures to go over a larger area of the asset in the direction that the texture is limited for that surface.

In this case, you would add polygons to the asset in order to repeat the texture further along the surface. This is why it is best to have tileable areas on the Trim Sheet in both horizontal and Vertical directions. This is a good example of editing the model to the texture, rather than creating the texture to the asset.

As you will need to be very precise with the polygon edges in order to tile correctly, one approach to this is to set the tileable edges on the texture to specific positions such as 50% or 25% height, so you can manually enter the position of the edge vertices to line up.

UV Maps use a 1 : 1 scale, so if the edge was 128 pixels of a 512 pixel image, you could set the edge height to 0.25.

Advanced approaches

If you've been following the tutorials through the Palette and Gradient Texturing tutorials you will no doubt have started noticing how powerful unwrapping UVs can be. You can take this knowledge and utilise it in both your texture creation as well as asset creation. Some approaches include :

• Combine Gradient and Palette texturing into the Trim Sheet in order to add flat or Gradient elements to the asset.

• Stretch or shrink UVs to warp the texture in interesting ways.

• Add polygons and utilise the UVs in interesting patterns.

As long as the texture resolution is high enough, and even in some cases where it's not, you can use the UVs of a texture in really creative ways resulting in asset that look great and are very performant.