I like very much the detail texture principle. I searched the web for implementations not using the GL extension ; but except the links you mentionned I did not find anything. So I finally came up with my own implementation.
I was wandering what kind of implementations exist ?!
For the piece of code I have :
- the geometry is drawn one more time with detail texture modulating the already drawn part,
- the detail texture coordinates are generated using the TextureMatrix to scale to objects original texture coordinates (by a value related to the original texture size in pixels)
- my detail textures are tweaked to have an alpha value, which allows me to fade the detail texture when it becomes too small & to use alpha testing : the different mipmaps of my detail textures have decreasing alpha values.