Hi everyone!
I want to map an out of range texture on a mesh, so I splited it
into several textures but It makes bad result on the edges when
I use linear mipmaps. can you help me please?

What do you mean "out of range"? A texture that is too big for your 3D-API to accept? If so, you should consider whether you really need such a large texture at all. Most (newer) video cards will accept textures up to 2048x2048, which should be plenty big.

However, if you really need to split it, you can help the mipmap issue by making each piece of the texture a bit bigger and including some of the pixels from surrounding pieces. Then modify the texture coordinates so only the center part of each piece is mapped. The extra "border" pixels will reduce the visibility of the seams at high mip levels.

yes I mean a texture that is about 4096*1024 and I already used the method you said but it is not good enough. so any other idea?

If I understand your problem correctly you could generate mip maps for the source texture map (4096*1024) and then cut up not only that map but also all of it's mipmaps to create your smaller mipmaps. This could be a time consuming process, but tools like the D3DX Texture Viewer and various mip-map tools from ATI and nVidia should help. I think this should work, just off the top of my head...

Mike.

OpenGL supports a border feature in textures.
This is essencialy the same solution that ReedBeta mentioned.
And if it is not good enought, then it's because it is not implemented correctly !
Check your implementation, and make sure you understand the filtering process, exactly, or the results won't be what you expect.

Thank you guys,
Mike's way sounds good but because I use compressed textures it's a little hard, I should uncompress and recompress the textures but not so bad :)
but Rui I tried that too and no result, even with my graphics card special extensions (ATI R96)