8
$\begingroup$

I'm having a bit of an issue getting started with UV mapping in Cycles. It works fine initially, but when I add the mapping node and set min/max to the default values to turn off repeating, I get the following stretch.

This is a bit boggling to me as I followed multiple tutorials where this exact same process works. See here

Images of the issue: http://imgur.com/a/0Ezqd

enter image description here

enter image description here

$\endgroup$
  • $\begingroup$ possible duplicate of Cycles option to turn off texture tiling? $\endgroup$ – Aldrik Aug 28 '13 at 14:02
  • $\begingroup$ @Aldrik Interesting. I tried out the node maps on that other question and while neither worked the question mentioned something about making the image texture larger than needed. So I increased the image canvas by 1px on all sides and the stretch went away. I assume it's now stretching the transparent pixel but it's not visible. $\endgroup$ – SirJay Aug 28 '13 at 15:49
5
$\begingroup$

As mentioned by Róbert László Páli, this is an artifact of the way the mapping node works.

You can get around this using hjaarnio's technique:

Using this node setup that creates a map of where the image is:

Example image

Values in the 0-1 range are where the original image is, so if we use that as a mix factor:

enter image description here

It will use the Image texture only where the original image is mapped, and Base Color everywhere else.

Base Color can be a texture or even another shader as well:

enter image description here

$\endgroup$
3
$\begingroup$

Enabling the min and max values for the mapping does the following:

When the coordinate for the UV is above the one
(when a certain point is above the image on
the UV) then it changes that value to one.

So the sampler will sample a pixel from the coordinate one, which is the topmost pixel of the image (and also the zero value is sampled from there). So for every point that is UV-mapped above or below the image, the color will be from the top row of the image. The same applies to the other direction.

A dummy solution would be to add one pixel transparent black border to the image to achieve a decal on the mug. But you have to use the alpha channel to mix the image with the original color.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.