fade multi-texture texture from one vertice to another?

I’ve got the ARB multitexture working but I want to fade, for example, a grass texture into a dirt texture between vertices.

Is that not a job for multitexturing? Do I have to make two passes and render the landscape twice using single textures and specifying alpha with glColor4f?

Yes you can do this with multitexture I think you need to use the env_combine extension so you can take vertex attribute directly into the second texture unit to apply the INTERPOLATE_ARB between the previous unit and the current texture:

http://oss.sgi.com/projects/ogl-sample/registry/ARB/texture_env_combine.txt

Thanks, I think that is what I want. I’m looking for a tutorial now but I’m not coming up with anything, has anyone seen one?