How to make texture repeat in X but clamp in Y? I'm trying to use blender to create a low poly mountain range.  To make the illusion of a long mountain range without using huge textures, I'm using two different uv layouts to layer a semi-transparent snow cap texture on top of my base rock texture.



For the base rock texture, I can just unwrap and let it seamlessly tile.



For the snow cap, I need to edit the uvs so that the top ridge is within the white region and then squish all the other uvs into the transparent region.



The problem is more obvious for mountains where the snow cap texture only comes down part way.  I suppose that I can squish all the uvs below that into the transparent region, but it would be nice if I could simply tell the graphics card to ignore everything outside of the texture region on the Y axis.  



I've used other software programs that let the user control how the texture is sampled when you go out of bounds (usually repeat/mirror/clamp.  Clamp just means that when you go outside the texture area, reuse the pixel on the closest edge of the image).  If I could clamp my snow texture in the Y axis, everying above the cap would be white and everything below would be transparent, making editing my uvs more flexible.

I could get around this by just moving my uvs around.  However, I wanted to know if Blender let you set the texture wrapping type too.
1. General solution (doesn't work in your case)
For many purposes, you can just change the texture repeat settings on the image texture node.

2. More complex solution (works perfectly in this case)
For more complex cases like yours, however, you this can be done quite easily with a mapping node:

Set the min value of, e.g., the y-axis to be whatever works best for your image. The setting 0.4 seems to work well for my simple testing setup shown below.