3D Real-time Cartoon Rendering February 2000

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v. 1.0

This is the sample application that accompanies the February 2000

Game Developer magazine. It is meant as a demonstration of

a method for Non-photorealistic cartoon rendering.

The February issue didn't really do any cartoon shading so there

wasn't much to do. Just the silhouette lines. Lots of people wanted

the app before the March issue though so I am releasing it.

But since you haven't seen the March issue yet, you won't know

about the shading method. So, here it is in a nutshell:

I use a 1D texture as a non-linear shading function. The dot product

of the light vector and the surface normal is used to calculate which

entry to grab out of that table. This gets rid of the Gouraud shaded

look and allows me to be very flexible on the shading.

For this demo, there are 32 entries in the shade table. This may not

be enough precision for some shaders. If you look at the "gradient.shd"

which is a smooth gradient, you will see the banding. This is also

because the bilinear filtering is turned off also. If it was on,

the shader wouldn't look like a Toon.

You can edit the .SHD files and create your own settings. They are

simple text files.

Model files are Wavefront OBJs. I get the model base color from the

Diffuse color in the MTL file.

Use settings to change the line color, width and light direction variables.

Anti-Alias may really slow things down on some OpenGL implementations.

This anti-aliases the sihouette lines.

Manipulating the View

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LMB to Rotate view in X and Y

LMB+SHIFT to Rotate in Z

RMB to Translate in Z

RMB+SHIFT to Translate in X and Y

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Stuff you can do to improve:

Add support for multiple materials and then add in material lines.

Add blending with a texture.

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Write to me if you have problems or questions and check

the web site or Game Developer's web site for updates.

Jeff Lander

jeffl@darwin3d.com

www.darwin3d.com/gamedev.htm

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I know this code could be optimized for maximum performance

but it was written to be a clean example without a lot of

tricks. It should be easy to learn and build from.

Here are the details.

I compiled the code with Visual C++ 5.0. It has been tested

with Microsoft OpenGL, SGI OpenGL, Permidia 1 and 2 OpenGL

Drivers, Riva 128 (New Beta OGL Drivers), AccelGalaxy,

and Symetra Ultra FX Pro.

It should run on any OpenGL fully complient driver. This

DOES NOT include the mini-QuakeGL driver for 3DFX Voodoo or

Voodoo 2. 3DFX Voodoo and Voodoo 2 OpenGL do not support

OpenGL in a window so will not work with this application.