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Texturing with UVs in Cinema 4D
Take Your Texture Game to the Next Level with Cinema 4D S22
Cinema 4D is the software of choice for 3D motion designers, but it has always presented a challenge in one area: texturing with UVs. It got to the point that a lot of designers avoided the task altogether. However, with the recent S22 update that Maxon unleashed in April of 2020, texturing with UVs has never been easier. In fact, this can be your new superpower!
In this article, I'll walk you through the basics of UVs, unwrapping, and the tips you need to be able to successfully texture your own models! Once you understand the process, you'll be amazed at how this improved workflow opens up your creative capabilities. Now slap some butter on a biscuit, it's time for another tasty tutorial!
Texturing with UVs in Cinema 4D
Download the Project Files
Follow along with EJ with the project files from the video!
Texturing with UVs Project FilesDownload Now
What are UVs and What is UV Unwrapping and UV mapping?
Let's begin by answering the question...what is a UV? UV's are the names of the horizontal and vertical axes of a plane, since XYZ are already used for coordinates in 3D space.
UV Unwrapping is the process of flattening out a 3D model into a 2D representation for texture mapping.
Think of a stuffed animal. It's made is by sewing together separated pieces of flat fabric based on a sewing pattern to create one sewn together animal. UV'ing is the process of defining seams and then unsewing or unwrapping a model at its seams to flatten it out to easily texture.
UV Mapping is then when you apply a texture and map it to your model using those UVs.
UV Unwrapping Basics
So why is there the need for UVs and unwrapping?
Let's drop in a cube. If we have a Cube and we try to wrap a UV Grid texture on it, you'll noticed that the texture looks great. Well, maybe it's just good. Okay, it looks fine.
Now what if we scaled this cube along the X axis? The texture stretches, deforming the checkerboard pattern. But why? Notice that UV grid texture is being mapped to a square texture space, and all of those cube polygons are on top of each other, mapping that UV grid texture to each side of the cube.
That square grid is now stretched out to fill the scaled up parts of the cube. UV unwrapping is the process of attempting to adjust the texture UVs so they look more like the actual 3D polygons (i.e. a rectangle vs. a square polygon). When your UV 2D polygons resemble the 3D polygons, textures map precisely onto your object so you can apply a texture with minimal distortion or stretching. Using this UV grid pattern is a great way to see the distortion.
Now you may be familiar with the different types of UV projections such as Cubic, Spherical, and Flat. Those might be the only UV workflows you’ve ever used in the past, and I’m sure you’ve realized that these methods only work in specific cases and aren't great for more complex geometry.
With Cinema 4D version S22 and above, there was a big update to the whole UV workflow setup, and now you have an auto unwrap feature that is super nice. With this, you can simply select an object, click Auto Unwrap, and viola—you have a quick and dirty UV map. For some purposes, such as exporting to game engines, this is good enough!
How to Unwrap
Auto Unwrapping has its place, but let's take a look at manually unwrapping.
I mentioned off the top that unwrapping is like unstitching a stuffed animal. To do this you need to define seams by selecting edges. The general rule is you want as few seams as possible.
We don't want a lot of UV islands that make your animal look like patchwork. The seams you do have you want to try to hide along hard edges or on hidden parts of the model—like on the backside of a model that isn't visible to the camera.
So here's a mushroom character that has a few different elements: We have the flatter top, and then the more cylindrical head area. How you approach UV unwrapping is dictated by the model you're working with, but it helps to visualize how the object could be un-stitched and flattened. Visualize those seams. We then work procedurally and place cuts/seams where they're not noticeable.
To unwrap this, we can separate out pieces like the top of the cap, the underside part of the cap, and then the base/head. The top of the cap is fairly easy. if you can visualize the seams and how we can flatten this out. To break this into the top and bottom, we can simply do a loop selection U>L and unwrap based on that seam. We can click UV Unwrap. Looking good!
Now we have to work on the base of the mushroom where it's a little more difficult. We can unwrap this like you would a head, where you create a seam in the back of the head and a loop selection at the base of the neck so to speak. This allows us to flatten the cylindrical part as well as the base of the mushroom. Now we won't exactly see the bottom nor the back of the mushroom, so we have some wiggle room there to hide those seams.
With our UV map all good to go, we can then paint directly on this model using Bodypaint, or we can export it out as an image and paint it in Photoshop, and then re-import and apply that texture to our model.
To export out a UV grid as an image, first create a new UV image texture by going to File > New Image.
It's best to save your textures in at least 2K (2048x2048). Then choose a brush size by going to BodyPaint Paint layout, adjust the hardness to 100%, make the brush smaller, and then with all polygons selected go to Layer > Outline Polygons.
Then go to File > Save Texture As... to save the texture with UV grid to a PNG or TIF, and now you can import into Photoshop and paint on it.
Texturing with UVs Like a Boss
Now that you have a handle on the basic process of defining seams and unwrapping, let's move onto the final boss.
Here we have a more traditional character with a head, torso, arm, and legs. We can approach this much like the mushroom character.
Let's begin with the head. We'll add seams much like we did with the base of the mushroom, where we can make a loop selection around the neck and create a seam up the back of the head. Once you have those seams selected, click UV Unwrap to unwrap those seams. Not happy with a result? You can undo and choose another seam.
Now onto the arms where we can also treat this like the cap of the mushroom where we made a loop selection horizontally to flatten out the top and the bottom of the mushroom. Let's make a loop cut around the armpit, and a loop cut around the whole of the arm so the top will be flat as well as the bottom of the arm.
If you make a selection on one side you can easily mirror that selection by using the Mirror Selection command. Click UV Unwrap and you'll see we flattened out the arms. You can also make the hands separate too and unwrap it like a half stitched glove. Onto the legs!
Depending on the texture you need to ultimately apply, you could unwrap the torso and the legs as one piece. I'll show you how to separate the legs and torso for this example. Let's first make a loop selection at the top of the leg, and then make a path selection at the back of the leg down to the bottom of the foot and click unwrap. (Use SHIFT double click on an edge to make a loop selection) Finally we'll unwrap and flatten the torso by making a loop selection at the waist sides and click Unwrap. It's quick and easy to test out cuts to figure out which cuts on which parts of your geometry work best, and the procedural way to unwrap is really forgiving.
Once you have your model unwrapped into separate islands, you can adjust the islands by using the transform gizmo to straighten out the face so it's horizontal and not diagonal, or adjust the size of an island so the UVs are about the same size on all parts of the model—this will help with any texture mapping.
Then you can follow the same workflow as with the mushroom, where you can save out a UV grid outline and paint your textures in Photoshop like I did, then reimport the texture into Cinema 4D and voila, you have a custom material mapped to your objects UVs...faster than a sloth can give a thumbs up!
You may not be able to shoot lasers from your eyes or fly, but you can UV unwrap—and that's pretty much the superhero-equivalent in the 3D world!
Just remember: "With Great Workflow Comes Great Responsibility!"
Want to Learn More About Cinema 4D?
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