Sounds like you are doing something wrong, maybe post some code?
You are using Addvertex with 6 coordinates the last two being u#,v# right (emphasis on floating point nature of coordinates and no don't set w#).
If you use CreateCube and texture it using LoadBrush and then PaintEntity do you get the same effect?
Also, not sure which manual you are reading but under AddVertex it states:
Which I'm not sure I agree with so await your reply with interest...
Also I assume you are not using TextureScale etc. which could easily give the disfigured results you are experiencing and are not talking about Terrains from what I recall have a mapping system all to themselves.
You are using Addvertex with 6 coordinates the last two being u#,v# right (emphasis on floating point nature of coordinates and no don't set w#).
If you use CreateCube and texture it using LoadBrush and then PaintEntity do you get the same effect?
Also, not sure which manual you are reading but under AddVertex it states:
the bottom left of an image has the uv coordinates 0,0. The bottom right has coordinates 0,1, top left 0,1 and top right 1,1.
Which I'm not sure I agree with so await your reply with interest...
Also I assume you are not using TextureScale etc. which could easily give the disfigured results you are experiencing and are not talking about Terrains from what I recall have a mapping system all to themselves.