This tutorial is dedicated to Polycount community.
2. Game models approach
3. Example of hairstyle
3.1. Tools used
3.2. Painting the hair texture
3.3. Hair geometry
3.4. Using normal maps
This is not a step by step tutorial. I will nail down the main stages for creating hair for game characters using lots of images and some print-screens directly from the application used (Maya/Photoshop etc...). The idea for this tutorial came from the Polycount forums; for the Dominance War II contest I joined Polycount team and the folks there asked me if I can make a little tutorial about Varga's hair so here it is...
This tutorial is about women's hair but the technique work for men as well; is just that I like long hair for women and my Dominance War II entry happened to be a chick.
I can write countless words about the importance of the hairstyle and the effect that the hairstyle adds to the personality of the character; we pay a lot (especially women) for a hairdo and we spend a lot of time styling our hair, or at least I am (every day in the morning I have to spend a few minutes to put some gel/foam in my hair, it does not matter if I will stay all day long at home and no one will see me, it's just that I am not feeling ok if I do not have my hair done) so I can not stress it enough that the hairdo will reflect the personality of the character ,that will add a strong touch to the mood.
Where do we find interesting hairstyles?
Well, there are a lot of sources of inspiration. First you have the internet where you can find tons of cool pictures, then fashion magazines, entertainment mags (playboy will do the trick ;) ) and a lot more ... people you see on the street ... for Varga's hair I was wandering around in a supermarket to buy some food and on a shelf I saw a box for Taft gel, ultra strong or something... and on the box there was a picture of a guy with his hairstyle in big clumps pointing in all directions that I liked a lot... it was before entering the Dominance War II competition ... after I started drawing the concepts I went in the same supermarket searching the One box :) because didn't manage to find it on the internet ... found it ... took a picture and left.
Below there are a few variations for the hairstyle, some of them will be covered in this tutorial.
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2. Game model approach:
There was a big problem concerning CG hair in the past but now there have been developed some solutions that will render realistic hair. For cinematic characters where the polygon count or texture size and numbers do not matter so much you have a lot of freedom and a lot of choices but when comes to game models you will always be limited to a number of polygons and number/size of the textures used. The solutions adopted for some time for more realistic hair is using textures with alpha (transparency). The problem is that the geometry mapped with transparency textures will add more computations to the render process and if you have some planes that will intersect and that have transparency textures that will be even worse; depending on the rendering engine there will be problems with the sorting algorithm (even at the version 8.5 Maya still has problems with transparency sorting when using high quality renderer in the view port ... the default opengl renderer works fine... there is a polygon transparency sorting option that does the trick but when comes to highQ renderer problems will arise...) so geometry with transparency is tricky... some of the engines I did models for required that the geometry mapped with transparency textures will not self intersect.
There is some sort of confusion regarding the terms alpha and transparency ... alpha is a separate channel in Photoshop channels window but transparency is available for each of red, green blue channels and can not be edited directly in Photoshop but only using the paint/erase brushes on the red/green/blue channels; these are the right definitions for alpha/transparency that I know... but I see that the terms are used interchangeably so I will do the same.
In the past there were used (or maybe there are still used ...) alpha test images (1bit alpha files) for transparency. Each pixel in the texture is either visible or invisible, no partial transparency is used; but now with the growing performance of the hardware the 8-bit transparency files are used. The 1bit transparency files will require fewer computations for displaying the geometry with alpha textures but the display quality will be poorer.
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3. Example of hairstyles:
Below I will show you some examples for some of the hairstyles shown in the first picture. I have chosen a different hairstyle than the one Varga has because it would have been boring for me to use the same hairstyle to make this tutorial :)
The first hairdo (normal1) is the usual one... I will not spend so much time on it because you probably can find a lot of tutorials about it on the internet. In a few words you will map a texture like the one below on some geometry extruded from the skull like in the figure below and then tweak the shape of the hair by moving the vertices around.
For this tutorial I will go with a more interesting hairstyle.