Lesson 3 - UvMapping Our Mesh
Mapping can be quite time consuming and confusing if you don't understand the concept behind it.
Mapping for Sims 3 is only slightly different from Sims 2. For Sims 3 you must map each part separetley, you cannot lie parts on top of each other.
As discussed earlier, each object mesh is made up of triangles or faces. The uvmap lets you plan out the "faces" in the image so that your texture will lay on the object correctly.
For example, take a basic cube. You want to make a dice. Your map would look like below. See how you can see 6 squares? Because a cube has six sides right? I've chosen the box mapping because it's a box type mesh. Ideally the mapping for the part of the mesh should match the shape of the mesh.
So if this is the map for your cube...we'd add the texture to the cube like below. See how I've lowered the opacity of the texture so you can see the map below?
Basically, all mapping is doing is planning out each part of your meshes faces so you can apply texture.
Now, the map above is easy because it's just one square mesh, 6 sides...simple. What if you have for example, a table top, 4 legs and 4 supports like we have? How many parts on the map would that be?
Table - top, bottom, side (3)
Leg 1 - 6 (front, back, left, right, top, bottom)
Leg 2 - 6
Leg 3 - 6
Leg 4 - 6
Support 1 - same shape as the leg, just scaled differently, so again, 6 sides.
Support 2 - 6
Support 3 - 6
Support 4 - 6
This is where it can get confusing. 51 sides to map. Just for a basic table.
Firstly before mapping anything we need to figure out how big our texture needs to be. Our texture is relative to the game dimensions. Remember that 512 pixels is 2 squares width in game. You have to estimate how big your texture needs to be based on the size of the mesh in game.
Now our table is 1x1 in game which is 256x256. But this texture wouldn't be big enough because you need to think about all the parts of your mesh. The table top is 256x256 pixels because it displays 1x1 in game, but what about the bottom of the table, the legs? So the table top and bottom would take up a region of 256x512 and I figure the legs and supports about the same, so our texture for this table will be 512x512.
1. Open UvMapper Pro.
Install and open UVMapper Pro. Once the program is open, go to File > Open Model and browse to our scaled table mesh.
Nothing much will happen, you'll just see some lines appear, not much else. I always find it helps to resize the mapper screen to the shape of the map we're using, so if we're doing a 512x512 square, resize your workspace to make it square too. Helps for scaling later on.
So, we have 4 legs, 4 support bars and one table top to map in this 512x512 square. Lets start off by seperating the parts and mapping them according to shape.
Go to Select > Select By > Group
You'll see a list of your groups appear. They should be named how you named each part/group in Milkshape when meshing. So you should have 4 legs, 4 support bars and 1 table top. Choose the table top group by clicking on it so it goes blue (highlighted) and click Ok.
You'll noticed now on the map some lines have turned red. This means that the lines showing are part of the table top mesh. Sometimes nothing changes when you select a group, nothing goes red but thats ok, just carry on with the next step.
Now, we have the table top group selected. We have to decide what map to apply to that part of the mesh. The table top was made from a cylinder and it has a top and bottom showing. So our best option is "Cylindrical Cap". This map will display the top, bottom and side of the cylinder. Go to Map > Cylindrical Cap
Choose the options as below and click Ok. (remember you can experiment with different options for different models, you may find a better way which you prefer.)
You should now see the table top map appear on your screen! It makes much more sense to look at it this way. You should see two circles and a long thin rectangle. This is our table top, table bottom and side stretched out.
It takes up a lot of space at present and we need space to sort the other parts out, so for now, with the table top map selected (red) hover your mouse over one of the corners so that you get a double ended diagonal arrow, drag the corner down to resize that whole table top map, make it small and move it over to the corner out of the way for now.
Now we need to move on to our next parts. For this part it's easier to select all at once, so go to Select > Select By > Group and select all the legs by holding Crtl and clicking on each leg group so all 4 are highlighted.
Now with all four leg groups selected, decide which map will suit the shape best. As our legs are "rectangle" they're box shaped and so we'll choose the box map. Go to Map > Box
And change the settings to match those below...
You'll now see the shapes of the legs appear. You won't see all of them, because remember, we selected all 4 legs, so some are on top of each other for now.
Do the same as before, resize the selected legs to make room for the next. Move the selection once resized next to the table top.
Again, lets do exactly the same for the support bars. Go to Select > Select By (or press Crtl & G) and then select all 4 support bars (hold ctrl and click each with mouse) and Ok.
With the support bars selected go to Map > Box (Box again as the bars are box shaped)
And same as before, resize down.
Now we've all our parts mapped and scaled down we can start to put together a map that will display the textures correctly.
Remember earlier I said that the table top would take up approx 256x256 (1x1) in the game? That would be a quarter of our 512x512 map. So take one of the circles and put it up in the corner and resize it so it fills about one quarter of the map.
Do the same for the other circle. Match it to the size you've made the first circle so that the textures will be proportionate.
You need to match the sizes of the map to the scale of the mesh in game and in Milkshape. If the parts are not proportionate to each other then the textures will appear differently and look strange. For example. If we mapped one of our legs so that it was the same width in the map as our table top then the texture on the leg in game would be hugely distorted because it is not as wide as the table top, it's very slim in comparison.
Do the same for the table edge, drag it out, estimate how thick it would be in comparison to the table thickness in game.
Ok, our table top looks pretty much correct. I'm gonna work on the legs next, so am just gonna scale down the support part of the map to give me a bit more space.
I've moved around parts of the table legs so that's they're neater and closer together. The closer together we map parts, the more space we have to play with. So I've made the table legs "tighter" and enlarged their map a little to see better.
Now, remember earlier we mapped all the legs together? That doesn't give us an accurate map because each part needs to be mapped separately. You only have 8 long parts (leg sides) currently and you should have 16, this means some are on top of one another. To seperate them simply go to Select > Select By > Group (Ctrl & G) and select one leg group.
You'll see some parts light up red. drag this selection out into a space of it's own.
Do the same with leg 2 (Select and move)
And with leg 3 too until you have all 4 legs seperate. You should now have 16 long sides and 8 squares. Obviously the 16 long sides are the lengths of the 4 legs. The 8 squares are the top and bottom of the legs.
Like we did earlier, arrange the legs next to each other, minimize the space between them.
The tops and bottoms of the legs won't be visible in the mesh because the tops are under the table tops and the bottoms face the floor. Anything that won't be visible in game can be resized really small and put to one side to save space.
Now we have space to scale our legs. Remember in game the table was just under 1 square tall. This means the legs need just under 256 in height for the texture to display correctly. So select the legs and scale up.
Now we've scaled the table top and legs, we just have the support bars to finish. Select them and make them a bit bigger so we can see what parts we have.
Notice when looking at the support bars mesh, some parts are mapped vertically and some mapped horizontally. If we left them that way, in game when people used any sort of pattern that wasn't plain, wood for example, you would get some parts of the support bars looking fine and some looking like the grain in the wood was going the wrong way, for example a horizontal bar with vertical wood grain. It looks awful!
So we need to rotate those parts to match the other parts in our map. As our legs are already mapped vertically it makes sense to match this so that the whole area can be coloured using one pattern in game.
Select the parts that are mapped horizontally by dragging your mouse over them. You can select more than one part by holding Shift whilst dragging.
Once you have the parts you want to rotate selected, go to Select > Rotate > 90 CW
You should then see immediately on your map these parts have flipped. You'll need to resize the rotated parts to match the size of the already vertical parts of the support bars map. Rearrange the vertical bars neatly together to save space, rotate any further horizontal parts...
Remember! Some of the support bars will be lying on top of one another, the same as the legs. So select each support bar by group (Select > Select By > Group) seperately and move them into position on their own, as you did with the legs.
Once all vertical and rearranged together, resize into the remaining space left like below
You can see below our finished map. It's pretty much full, which is what we want. You should take advantage of all of the space to maximise texture for each part. Also note the scale. The table top and bottom fill half the map, the legs are around the same height as the table, the support bars are shorter than the legs and thinner...similar to appearance in the game.
You can now save your mapped table. Go to File > Save Model, copy the choices below and hit Ok.
Now save the mapped .obj by overwriting your scaled table mesh.
Now save your map image by going to File > Save Template and saving the .bmp to our working folder along where your mesh files are stored.
That is the basics of mapping finished. I will be adding an "extras" to explain how to save space when mapping by using Blender. That will be added after the main lessons are finished and is useful for mapping objects where some of the faces are not visible.
You may download this lesson below.
.doc (Word)
You have until Thursday 2nd September to complete lesson 2 and 3. Please display the image of your finished map. It will be 512x512, the .bmp template you save at the end of the lesson.
In our next lesson we will be regrouping our mesh, importing our mesh to overwrite the orginals, both high and low and creating our sunshadow meshes.
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You're quick Tinks and it looks perfect. 
