I'm creating a tile based game but I hate the look of the independant tiles ending abruptly...
I have come up with an idea of using a shader but I would like some feedback/input of other approaches you guys may have.

So far my idea is to use simple entities (2 polygon square) instead of sprites so I can have multimple skins.
Each entity will have four skins. At creation the first three skins are the same (the base texture of the tile) and the fourth is a "blend-map". An example of the fourth skin is shown above.
when the level is created each tile will have it's second skin set as the same as the tile to the north, and the third skin set the the same as the tile to the east.
My initial idea is to use a simple shader that will sample the first skin and blend it with the 2'nd and 3'rd using the fourth. Where the fourth is coloured black the shader will sample the first skin, where it is red the second skin will be blended over it, and where the fourth skin is green it will blend the third skin.

But I am not too happy with the results this shader would produce... I have tried to come up with different "blend-skins" but the results all seem to be terrible when i duplicate and colour it in to see what the shapes would look like. An example for the tile skin shown above would be this:


I am not asking for the shader to be done for me nor asking for code. What I want are concepts... I know many games blend tiles pretty well but I can't seem to figure out how they do this.

So basically what I have is a design problem, I'll deal with the programming myself once I know what to program. I have a couple questions for anyone that has any ideas for this.

-If this shader idea is the best route... Could I get any examples of what you think the fourth (blend-map) skin should look like for this to look good?

-Do you have any better ideas? Mabe it is much simpler than what I am trying to think about. Mabe there is a better approach to this shader, mabe three skins are not needed, mabe it can be done some other way withought using a shader alltogether! I am all ears for any other concepts you guys come up with.

hmm..
One way is to create Tiles that fit perfectly together and build a transition between two ground/wall types. But thats much work to create all the middle tiles

another way would be, for example, to put a red and a yellow tile to be half overlapping each other.
And the shader now blends the pixels of the tile obove, to the tiles below.

But i always think that could be ugly, so in my early projects, i used my first method ^^"

I thought of that at first, pre-defined tiles for touching tiles. (If I understood you correctly that is what you are saying?)

If that is the case, I discarded that idea when I realized the amount of tiles I would need.

Just putting my thoughts out there about how many blended pre-made tiles would be necessary. Mabe I'm just over-thinking it and it would require much less tiles?

I have not fully understood your second idea and am very interested if you could explain that a little more. Mabe I have a thick skull today, but I do not understand the second idea no matter how many times I read it.

You could also do it the way the rpg maker 2k solved it:
http://img266.imageshack.us/img266/7127/tilea2dc5.png
http://tilesettutorial.wordpress.com/

what I found a practical way in case of tiles, to have first a map filled with a default 24b tile (or have a 24b base image in case of using terrain as a base), and then put the 32b tiles having borders with alpha fade out for good blending with the images placed previously.

As a better and more randomized approach, later I used a separate grey-scale image storing the alpha fade out values, and used large texture files instead of tiles. Their repetition is dependent on their size, so can be different for each texture, while you can also change randomly the alpha fade out image - if you make more versions.

It was my first trial project with 3DGS I used it for tile aligned painting of terrain texture (using a multi-terrain system, so neighbouring terrains were also painted), plus during painting tile settings are also can be managed. You need an editor for this, or create randomly.

thanks!