Real-time 3D Painting September 2000

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v. 1.0

This is the sample application that accompanies the September 2000

Game Developer magazine. It is meant as a demonstration of

a method for simple painting directly on a 3D object.

Load an OBJ file with texture coordinates and a texture map. (Note: this

method works best with textures 256x256 and below). You should

then see it come up in the view. You can turn lighting on/off via the

menu. Also toggle bilinear filtering with the menu.

Painting

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LMB and drag across the object to paint with the current brush

LMB+SHIFT to select the color under the mouse as the current pen color

Manipulating the View

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RMB to Rotate view in X and Y

RMB+CTRL to Translate in X and Z

RMB+SHIFT to Translate in X and Y

MMB to Translate in X and Z

You can also change the pen color through the menu option. Once the

object is painted the way you like it, save the file out as a TGA to disk.

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Stuff you can do to improve:

This is a pretty simple paint system. Quite a bit can be done to

improve it.

1. Make the color selection a swatch that is always active.

2. Allow for different sized brushes and brush types.

3. Track the stroke pattern and then stroke the texture afterwards in a smooth manner.

4. Allow for an alpha component to the brush color then mix with the texture.

5. Add support for multiple UV channels, bump mapping, etc.

6. Improve the selection buffer so it handles large textures better.

October's issue covers mapping coordinate methods. Part of that code is included in

this build. You can reset the UV coordinates on the objects based on different mapping

methods. These will be finished up next month, but for now you can check it out. The final

will include other mapping methods as well as the ability to save the final OBJ.

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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++ 6.0. It has been tested

with Microsoft OpenGL, Permidia 2 OpenGL, NVidia TNT, TNT2, GeForce256.

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.