How to remove seams from a tile map in 3D?

Question

I am using my OpenGL custom engine to render a tilemap made with Tiled, using a well spread tileset from the web. There is nothing fancy going on. I load the TMX file from Tiled and generate vertex arrays and index arrays to render the tilemap. I am rendering this tilemap as a wall in my 3D world, meaning that I move around with a fly camera in my 3D world and at Z=0 there is a plane showing me my tiles. Everything is working correctly but I get ugly seems between the tiles.

I've tried orthographic and perspective cameras and with either I found particular sets of parameters for the projection and view matrices where the artifacts did not show, but otherwise they are there 99% of the time in multiple patterns, depending on the zoom and camera parameters like field of view.

Here's a screenshot of the artifact being shown: https://i.sstatic.net/5y3kr.png Here's the tileset I am using (which Tiled also uses and renders correctly): https://i.sstatic.net/SD48p.png

My tileset has no mipmaps and is set to GL_NEAREST and GL_CLAMP_TO_EDGE values. I've looked around many articles in the internet and nothing helped.

I tried uv correction so the uv fall at half of the texel, rather than the end of the texel to prevent interpolating with the neighbour value(which is transparency). I tried debugging with my geometry and I verified that with no texture and a random color in each tile, I don't seem to see any seams. All vertices have integer coordinates, i.e, the first tile is a quad from (0,0) to (1,1) and so on. Tried adding a little offset both to the UV and to the vertices to see if the gaps cease to exist. Disabled multisampling too. Nothing fixed it so far.

Thanks.

Answer 1

I'm sorry but I solved it myself. I was dumb enough to perform the texel correction wrong the first time, and now I came back to it and did it properly, everything started working properly with no visible artifacts.

Feel free to delete my question; Either way, here's the solution for the correct UV's:

vec2 texel_correction(1.f / tilesetWidth , 1.f / tilesetHeight);

topLeftU = float(tileLeft) / tilesetWidth + texel_correction.x; 
topLeftV = float(tileTop) / tilesetHeight + texel_correction.y;
bottomRightU = float(tileLeft + tileWidth) / tilesetWidth - texel_correction.x;
bottomRightV = float(tileTop  + tileHeight) / tilesetHeight - texel_correction.y;