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(For more resources on Blender, see here.)
Before we can create a custom UV texture, we need to export our current UV map from Blender to a file that an image manipulation program, such as GIMP or Photoshop, can read.
Exporting our UV map
If we have GIMP downloaded, we can export our UV map from Blender to a format that GIMP can read. To do this, make sure we can view our UV map in the Image Editor. Then, go to UVs | Export UV Layout.
Then save the file in a folder you can easily get to, naming it UV_layout or whatever you like.
(Move the mouse over the image to enlarge.)
Now it’s time to open GIMP!
Before we begin, we need to first get an image manipulation program. If you don’t have one of the high-end programs, such as Photoshop, there still is hope. There’s a wonderful free (and open source) program called GIMP, which parallels Photoshop in functionality. For the sake of creating our textures, we will be using GIMP, but feel free to use whatever you are personally most comfortable with.
To download GIMP, visit the program’s website at http://www.gimp.org and download the right version for your operating system.
Mac Users will need to install X11 so GIMP will run. Consult your Mac OS installation guide for instructions on how to install.
Windows users, you will need to install the GTK+ Runtime Environment to run GIMP—the download installer should warn you about this during installation. To install GTK+, visit http://www.gtk.org.
When we open GIMP for the first time, we should have a 3-window layout, similar to the following screen:
Create a new document by selecting File | New. You can also use the Ctrl+N keyboard shortcut. This should bring up a dialog box with a list of settings we can use to customize our new document.
Because Blender exported our UV map as an SVG file, we can choose any size image we want, because we can scale the image to fit our document.
SVG stands for Scalable Vector Graphic. Vector graphics are images defined by mathematically calculated paths, allowing them to be scaled infinitely without the pixilation caused when raster images are enlarged beyond a certain point.
Change the Width and Height attributes to 2000 each. This will create a texture image 2000 pixels wide by 2000 pixels high. Click on OK to create our new document.
Getting reference images
Before we can create a UV texture for our wine bottle, which will primarily define the bottle’s label, we need to know what is typically on a wine bottle’s label. If you search the web for any wine bottle, you’ll get a pretty good idea of what a wine bottle label looks like. However, for our purposes, we’re going to use the following image:
Notice how there’s typically the name of the wine company, the type of wine, and the year it was made. We’re going to use all of these in our own wine bottle label.
Importing our UV map
A nice thing about GIMP is that we can import images as layers into our current file. We’re going to do just this with our UV map. Go to File | Open as Layers… to bring up the file selection dialog box.
Navigate to the UV map we saved earlier and open it. Another dialog box will pop up—we can use this to tell GIMP how we want our SVG to appear in our document.
Change the Width and Height attributes to match our working document—2000px by 2000px. Click on OK to confirm.
Not every file type will bring up this dialog box—it’s specific to SVG files only.
We should now see our UV map in the document as a new layer.
Before we continue, we should change the background color of our texture. Our label is going to be white, so we are going to need to distinguish our label from the rest of the wine bottle’s material. With our background layer selected, fill the layer with a black color using the Fill tool.
Next, we can create the background color of the label. Create a new layer by clicking on the New Layer button. Name it label_background.
Using the Marquee Selection tool, make a selection similar to the following image:
Fill it, using the Fill tool, with white. This will be the background for our label—everything else we add with be made in relation to this layer.
Keep the UV map layer on top as often as possible. This will help us keep a clear view of where our graphics are in relation to our UV map at all times.