We now have a complete model of Kila, our main character. She has all the detail we need at the momentbut this also means we may have gone over our polygon budget. In the next chapter, we will examine areas where we can optimize, removing any geometry that is not needed.
Chapter 5. Model Optimization
UNTIL NOW, we have spent our time developing a good, clean model without worrying too much about the polygon count. That's about to changein this chapter, we will be removing a lot of the details you have sculpted into Kila so far. Try not to think of this step as destroying all your hard work, however. What you've accomplished so far is to create a character that is complete and has all the embellishment it needs to have. With all these details in place, we can now make informed decisions about the places from which we can remove those details. That's what optimization is all about.
You will find as you gain more experience in modeling game characters that the optimization stage will gradually become less important, because you will learn to analyze the topology automatically, from the moment you begin building. For the novice artist, this chapter tells you exactly what you need to be looking for as you optimize your character.
With every model, you will find areas where polygons have been placed but are not needed. Essentially, we want the model to have as few polygons as possible. Our polygon limit for this project, established in Chapter 1, is 4500, and we don't want to use more than that number. Indeed, after optimization we may very well end up well under our budget, which is good. If not, we will start to look at areas that we can sacrifice in order to bring the polygon count down.
Deciding What to Remove
It's important to decide carefully about where to remove polygons from the geometry. Remove the wrong ones, and the shape of our character will change dramatically. It could also result in bad deformation in the game.
The first two sorts of polygons you should consider for removal are unnecessary polygons and polygons that form shallow angles.
Your model is currently made up of hundreds of polygons, and almost all of them are needed. You may think that a polygon's actual presence means it is necessary to a model, but this is not the case.
So how do you determine which polygons will be unused? An unnecessary polygon is one that does not add to the shape of the mesh, nor does it aid in its deformation.
Look at the two cubes in Figure 5.1. They look exactly the same; the only way they differ is in construction.
Figure 5.1. Although these cubes look the same, they are constructed differently.
Now look at their wireframes in Figure 5.2. You can see that the one on the right contains more polygons than the one on the left. Since the edges are straight, the cube does not need the extra polygons to create that straight edge. If we removed these polygons, the cube would look exactly the same.
Figure 5.2. In the wireframe, you can see that the cube on the right unnecessarily uses far more polygons than the one on the left.
Removing areas that contain shallow angles is also a good way to reduce the polygon count, although this will slightly affect the way the geometry looks.
Take a look at the cylinders in Figure 5.3. Do you see a difference? The one on the right has a very slight bump in it. This is a shallow angle, and it adds so insignificantly to the shape of the geometry that no one would miss it if it were gone.
Figure 5.3. Two cylinders
We now know what to look forunnecessary polygons and shallow anglesso let's move on and begin optimizing our character model.