I've decided to release my cel shading system for free.
It's not the sort of thing which is large or compelx enough for me to actually sell, so lucky you. :-)
DT Smash TestThe system takes 1d textures as imput, basically 1 pixel wide vertical gradients, and turns them into proper spherical maps with correct distortion.
Note that when you use this system, the direction of the light will be in realtion to the orientation of the camera.
In other words, if your light is not directly overhead, and you turn the camera left or right, the apparent direction of the light source will change.
This is a limitation of doing cel shading with spherical maps.
If your light is directly overhead then you can rotate the camera left and right and the ligh's direction will remain consistent. However, this is only true as long as you do not pan the camera up and down.
If you want a camera that points down at an angle, then you will need to transform the light's position by the camera's pitch so that the top of the shading map points more towards the front of the sphere map.
It is hard to explain how to do this, so if you don't understand, don't worry about it. Just tweak the location of the light source until it looks right.
In case you're wondering, the demo above shows a character from something I'm working on with the fellow who does this online comic:
http://www.dragon-tails.com/There's only one model at the moment and he's not animated, but you can see the nice cel shading maps I created. At first I tried to use cel shading maps that just modulated the colors of the underlying model. That would have been the simpler solution. But the result of that was HIDEOUS looking.
My goal was to match the look of the following image:
Dragon GroupAs you can see, I succeeded in getting the models to look almost exactly like this hand drawn image, right down to the way the metallic dragons have a special sort of sheen to them.
Of course to see that effect I suppose you'll need to know how to control the demo...
The controls are:
Arrows rotate model
A+Z zoom in and out
1-8 select different textures.
So anyhow, this demo will show you exactly what you need to do to use this cel shading system of mine. It's still a bit of a work in progress, but at this point it's more than adequate for a game.