For my game's terrain I need to be able to get the terrain type under the player's feet,so it's divided into square tiles,but that turned out to look very ugly,isn't there some way to put another channel in the texture,so it's like RGBAT,where T is TerrainType.So I could just smear the textures however I want and then just check the pixel at a given location and match it's T value to the corresponding terrain type(ex;T(0) = grass,T(1) = gravel,ect.).

no, but ganeral technique to achieve what you are after are vertex colors. With theese you can even blend textures to fade between eachother.

I don't think there is a surface type with 5 channels. But if you want to try this method then I have a question - do you really need the Alpha channel for anything? Terrain usually isn't transparent, so instead of RGBAT where T is terrain type, couldn't you use RGBA where A is terrain type?

Anyway, I would suggest something completely different, if I understand your problem correctly. The term for this approach probably is texture splatting as ryan20fun mentioned. The point is that you have for example three different tiled textures (let's say grass, dirt, sand). Then you have one special texture covering the whole terrain without tiling - this texture defines in its color channels how the tiled textures should be combined. If the color is (1, 0, 0) then only grass will be visible etc. And the huge bonus is that you can blend the textures because (0.7, 0.3, 0) will give you 70 % of grass blended with 30 % of dirt.

This will be much easier to work with and much more flexible, because in your suggested idea you have only one channel defining the terrain type, while here you have a full texture (4 channels). And also - this texture can have different texture coordinates (different tiling) than the subtextures.

I don't think there is a surface type with 5 channels. But if you want to try this method then I have a question - do you really need the Alpha channel for anything? Terrain usually isn't transparent, so instead of RGBAT where T is terrain type, couldn't you use RGBA where A is terrain type?

Anyway, I would suggest something completely different, if I understand your problem correctly. The term for this approach probably is texture splatting as ryan20fun mentioned. The point is that you have for example three different tiled textures (let's say grass, dirt, sand). Then you have one special texture covering the whole terrain without tiling - this texture defines in its color channels how the tiled textures should be combined. If the color is (1, 0, 0) then only grass will be visible etc. And the huge bonus is that you can blend the textures because (0.7, 0.3, 0) will give you 70 % of grass blended with 30 % of dirt.

This will be much easier to work with and much more flexible, because in your suggested idea you have only one channel defining the terrain type, while here you have a full texture (4 channels). And also - this texture can have different texture coordinates (different tiling) than the subtextures.

I don't think there is a surface type with 5 channels. But if you want to try this method then I have a question - do you really need the Alpha channel for anything? Terrain usually isn't transparent, so instead of RGBAT where T is terrain type, couldn't you use RGBA where A is terrain type?

Anyway, I would suggest something completely different, if I understand your problem correctly. The term for this approach probably is texture splatting as ryan20fun mentioned. The point is that you have for example three different tiled textures (let's say grass, dirt, sand). Then you have one special texture covering the whole terrain without tiling - this texture defines in its color channels how the tiled textures should be combined. If the color is (1, 0, 0) then only grass will be visible etc. And the huge bonus is that you can blend the textures because (0.7, 0.3, 0) will give you 70 % of grass blended with 30 % of dirt.

This will be much easier to work with and much more flexible, because in your suggested idea you have only one channel defining the terrain type, while here you have a full texture (4 channels). And also - this texture can have different texture coordinates (different tiling) than the subtextures.

Yeah,I figured it out - I'll generate 2 blendmaps(for 2xRGBA (8 terrain textures total)) on the CPU and each time a piece of the terrain is changed,I'll lock the blendmaps and change them in the cpu,then unlock again.It shoudln't cause a slowdown,since the terrain won't change more often than once every 5-10 seconds.