Vertex Manipulation 2
Reducing Brush Counts & R-Speeds using comples brushes.

Ok, I'm assuming that you've already got some experience with the vertex manipulation tool or read the first tutorial of this series. If not, then I would recommend learning about this tool before going ahead with this tutorial as it'll help you understand this.

Ok, so what exactly does this tutorial cover? Well, there is a limit to the amount of brushes that a level can have. These are 8192 (using zoners compile tools) and about half this amount if you're using the standard compile tools that come with Hammer. So, if you've got a set-up of a block and a wedge, you have 2 brushes. However, using vertex manipulation, you could reduce this to 1, allowing for a more complex and bigger map to be made.
So this means that you can make more interesting brushes for your map, and also less brush count.

So lets take the example of the wedge. Here, we have a block and a wedge:



Ok, now here we have a total of 2 brushes. Now, if you have this in 10 different places in your map for doorsteps or ramps, etc, you will have 20 brushes from these alone.
Now, to reduce this count, you can do the following:

Make a block like below and go into vertex manipulation mode. I've got one of 768 x 320 x 128.



Next step is to select in the 3D view, the edge on the top of the right side of the brush, and drag it back towards the centre of the block, like so:



And there you have a wedge! This has saved on brush use for the map and also the amount of brush faces in your map. This may not seem much, but say you've got a block and a wedge for 20 doorsteps in the map and 5 ramps in your level, that's 50 brushes in total. With this method above, you will have cut this in half, to 25. This is very useful for larger maps and also compile time, as well as r_speeds! Lots of good things there! 

But why? Well, the more brushes you have, the longer your compile time will be, both on CSG and VIS. So if you've halved the amount of brushes used, you've chopped off a lot of time that VIS will take to compile your map. 
Also, it will be reducing r_speeds by the fact that instead of the engine having to draw two brushes, it draws one instead. In a high w_poly area, this application can work wonders on reducing it. And, since doorsteps will be quite small, VIS won't have to be rendering two small brushes, it will have to be rendering one bigger brush. This is good because big brushes are rendered faster.

Note that this can also be done using the clip tool.

Now, obviously, there are more things that this can be applied to. Corner sections of walls are an example. Not only can you reduce the amount of brushes used, you can also give the corner a better look, rather than a 90 degree angle.

Here we have a corner:



Now, going on the information above about compile times and engine rendering, this will be bad for rendering. Two brushes, that are also thin = slower rendering. So what can we do? Well, our friend, vertex manipulation can be applied!

First of all, create a 5 sided cylinder and go into vertex manipulation mode:



Now, adjust the shape until you have this:



Replacing the two-sided corner we had earlier, we now have this:



There we go! Looks much better than a 90 degree angle and we now have cut the brushes in half (2 to 1!). The brush is a lot bigger as well, so less rendering time spent too. 
If you had that corner of two brushes in 50 places in your map, that's 100 brushes in total. Instead, you can have 50 brushes, with 7 faces per corner rather than 12 using this method. Both counts are a lot lower, allowing for a better-looking map to be made!

These are only two examples of reducing brushes by using complex brushes, but are the most common and simplistic ones I could think of for the tutorial. I know there are other ways of reducing brush count using this method, I'm just not going to explain all of them!

Remember, If your r_speeds are bad, and you've not tried this method yet, it could be worth giving it a shot, as I brought mine down from 800 to 650 using this method in one area on a map!

NB: After you finish using vertex manipulation on any solid and you like the outcome, always do a test compile and check for problems. This way, if its wrong, you can fix it straight away. 

By The God

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