First of all, allow me to poke some holes in your suggested method for expanding on that method:

First of all, you have a maximum of 16 texture samplers to use (ps_3_0 registers). So that is the limit of the expandability of the method you linked.

Second of all, each texture sampler in use will add to the texture bandwidth usage of your shader. (You may be able to mitigate this with conditionals in your shader - but I will leave you to do the experiment to see if it actually works.)

Finally, if you embed your "what texture to use" data in a texture, rather than as vertex data (as the tutorial you linked does), then you use up an available texture slot.

So, what are these games doing? I am going to take an educated guess:

First of all, they are probably using a multi-texturing technique similar to the one described in your link. They are possibly doing some tricks with this, for example: using different texture resolutions for detail and scrottox layers.

It also seems (I've been skimming this PDF) that their map builder is automatically chopping up the terrain mesh to allow different sections to use different textures, providing they are in different parts of the map. Thus increasing the number of available textures by increasing the number of batches rather than the number of samplers used (which seems like it would be better for performance).

I must admit - I am not sure how they're getting sharp edges in places - like the roads, while having blended edges elsewhere. But apparently roads are baked into the terrain texture somehow.

And finally, they are possibly also using decals to add fine detail to the map.

First of all, allow me to poke some holes in your suggested method for expanding on that method:

First of all, you have a maximum of 16 texture samplers to use (ps_3_0 registers). So that is the limit of the expandability of the method you linked.

Second of all, each texture sampler in use will add to the texture bandwidth usage of your shader. (You may be able to mitigate this with conditionals in your shader - but I will leave you to do the experiment to see if it actually works.)

Finally, if you embed your "what texture to use" data in a texture, rather than as vertex data (as the tutorial you linked does), then you use up an available texture slot.

So, what are these games doing? I am going to take an educated guess:

First of all, they are probably using a multi-texturing technique similar to the one described in your link. They are possibly doing some tricks with this, for example: using different texture resolutions for detail and scrottox layers.

It also seems (I've been skimming this PDF) that their map builder is automatically chopping up the terrain mesh to allow different sections to use different textures, providing they are in different parts of the map. Thus increasing the number of available textures by increasing the number of batches rather than the number of samplers used (which seems like it would be better for performance).

I must admit - I am not sure how they're getting sharp edges in places - like the roads, while having blended edges elsewhere. But apparently roads are baked into the terrain texture somehow.

And finally, they are possibly also using decals to add fine detail to the map.

First of all, allow me to poke some holes in your suggested method for expanding on that method:

First of all, you have a maximum of 16 texture samplers to use (ps_3_0 registers). So that is the limit of the expandability of the method you linked.

Second of all, each texture sampler in use will add to the texture bandwidth usage of your shader. (You may be able to mitigate this with conditionals in your shader - but I will leave you to do the experiment to see if it actually works.)

Finally, if you embed your "what texture to use" data in a texture, rather than as vertex data (as the tutorial you linked does), then you introduce a dependent texture read, which can have performance implications. Also it uses up an available texture slot.

So, what are these games doing? I am going to take an educated guess:

First of all, they are probably using a multi-texturing technique similar to the one described in your link. They are possibly doing some tricks with this, for example: using different texture resolutions for detail and scrottox layers.

It also seems (I've been skimming this PDF) that their map builder is automatically chopping up the terrain mesh to allow different sections to use different textures, providing they are in different parts of the map. Thus increasing the number of available textures by increasing the number of batches rather than the number of samplers used (which seems like it would be better for performance).

I must admit - I am not sure how they're getting sharp edges in places - like the roads, while having blended edges elsewhere. But apparently roads are baked into the terrain texture.

And finally, they are possibly also using decals to add fine detail to the map.

First of all, allow me to poke some holes in your suggested method for expanding on that method:

First of all, you have a maximum of 16 texture samplers to use (ps_3_0 registers). So that is the limit of the expandability of the method you linked.

Second of all, each texture sampler in use will add to the texture bandwidth usage of your shader. (You may be able to mitigate this with conditionals in your shader - but I will leave you to do the experiment to see if it actually works.)

Finally, if you embed your "what texture to use" data in a texture, rather than as vertex data (as the tutorial you linked does), then you use up an available texture slot.

So, what are these games doing? I am going to take an educated guess:

First of all, they are probably using a multi-texturing technique similar to the one described in your link. They are possibly doing some tricks with this, for example: using different texture resolutions for detail and scrottox layers.

It also seems (I've been skimming this PDF) that their map builder is automatically chopping up the terrain mesh to allow different sections to use different textures, providing they are in different parts of the map. Thus increasing the number of available textures by increasing the number of batches rather than the number of samplers used (which seems like it would be better for performance).

I must admit - I am not sure how they're getting sharp edges in places - like the roads, while having blended edges elsewhere. But apparently roads are baked into the terrain texture somehow.

And finally, they are possibly also using decals to add fine detail to the map.