Today we are going to learn about UV unwrapping, just some basics but before that I am going to answer some questions like
What is UV unwrapping? Is it necessary to unwrap UV?
UV unwrapping is the process of 'unfolding' a mesh so that you can create a 2D texture which fits the 3D object. Or in other words, it is basically used just for mapping images onto your 3D model.
It's not necessary but if you wish to texture your object very accurately, you will need to do it.
If your 3D model is not unwrapped then you would have to use a different mapping method, but you generally have less control of how the image will be mapped using those methods and they wouldn't be compatible with game engines as far as I know.
For some uses, UVs might not be needed, but it is recommended if you need to add specific details. But its a good habbit to use UV map per model. Especially when there are disconnected pieces. for example, if you have made a character, then you can use one map for the body and one for the clothes. It all depends what your texture looks like.
So, Lets start with creating a simple box
Now, apply Unwrap UVW modifier to this box & hit the button 'Open UV Editor'.
As you can see in the UV editor there is a box with grey & white checkers pattern in it, which is your canvas. Any texture you apply comes in this region only.
Now, if you see its looks just one flat polygon but if you select it (right click, select face & then select it) & move it, you will see another same size polygon. So all the 6 faces of the box are lying on one another.
So, if you apply a texture then every face of the box will get the same design.
So now you can do is to take every face, re-size them and keep them side by side manually or just select all the faces, go to menu - mapping - flatten mapping. Now you have all the faces lined in the box. By doing this you can paint each face as you want.
As you can see, every face have the piece of texture where its placed on the image (box in UVW Editor), but its not symmetrical.
As you can see every face have green lines (known as seems) so now select the edge of any face in UV editor, right click - stich selected.
Now as you can see in above image, faces with out seem have symmetrical texture.
So now select the rest on seems one by one and stitch them.
As you can see every face have green lines (known as seems) so now select the edge of any face in UV editor, right click - stich selected.
Now as you can see in above image, faces with out seem have symmetrical texture.
So now select the rest on seems one by one and stitch them.
Now you have the unwrapped UV of this box.
So, now lets move to a little more complicated object
So I just took a box and made a rough model of car and applied smoothing groups to make the edges soft.
Now, Lets start with unwrapping.
for ease apply checkers as texture. It will help to get better and quick results.
Now add UVW Modifier and open UV editor
As you can notice the texture, it totally misfits because the faces in UV editor overlap.
So, next thing you are gonna do is select all the faces, go to menu - mapping - flatten mapping.
Now if you see most of the checkers are perfectly set and are of same size but still its divided in many pieces.
So we are going to do it the easy way. We are going to take faces on every axis (X,Y,Z) and the stich them together.
Now select all the face on Z direction. Go to projection panel and hit planner mapping icon and align it in Z direction.
Now take it aside and adjust it so that you could get square shapped, equal sized faces
Leave it as it is and now go for next axis, Y-axis that means the side area of the car. Select all the faces on one side Y-axis - planner mapping - align it - adjust it bring it next to the top area.
Do the same for the other side. Don't be mad if you cant adjust it accurately.
Now select edges and stich the faces of windows and side with top
If you see some distorted faces, go to menu - tools - relax. Do not change any thing, just try the options relax by face angles, relax by edge angles, relax by center one by one, whichever suits you best.
As you can see, seems are gone and checkers are even.
Do the same for the other side.
Now take the front faces and back faces one by one and adjust them.
Now select all the three pieces, go to menu - tools - pack UVs.
So you get the result something like this.
Now again go to menu - tools - Render UVW template.
Select the size you want and hit render UV template. Save it in any format you want.
Take the saved template in photoshop and start painting (texturing).
Once you are done, apply it to your model. I used some alpha map to give it little bump.
