I have a problem.
I UV mapped a texture bricks.
Now I have to paintere on this UV mapped texture.
Once I get into TEXTURE PAINT, the problem is this.
The texture is not seen in the right scale, and if I paint a part of the texture the paint is repeated on other points of the texture.
There are 2 kinds of textures that are often used in 3D:
1-Seamless textures that repeat multiple times over a model (The brick texture is of this type.). These can be reused on different 3D models and the repetition can allow the texture to look like it has a lot of resolution, but they have visible repeating patterns and won’t allow custom details on different parts of the model.
2-Painted texures that are custom made to match a specific model. When using this type of texture, the model has to be carefully and cleanly UV unwrapped. Then, the texture is painted on the model and will match its UVs. This allows custom details on different parts of the model, but at the cost of getting less texture resolution (because the texture can’t repeat over the model) and also the fact that it can’t be re-used on an other model.
Of course, you can’t paint a new detail on a repeating texture without having that detail also repeat. But there are other ways to achieve that effect. Let’s say you are trying to add a word written on a single brick of the building:
1-You could do it as a separate plane with a transparent texture.
2-An other method would be to create 2 versions of the brick texture (like, duplicate the image file and make a second version with the word added) and blending between the 2 versions based on a painted mask. With this method, you would create a new blank image and you would paint on that instead of painting on your existing brick texture. then, you use the newly painted mask as the “fac” of a mix node and you can blend between 2 textures. Here is a tutorial.
This second method can be useful at large scales to make (ex.) a brick texture vary in dirtiness across different parts of a building. You make a second, dirty version of the brick texture and mix between the 2 so the bricks become increasingly dirtier near the bottom of the walls.
In the material editor, your texture is most likely scaled with a mapping node. However, the basic viewport cannot display material nodes like this. You will have to switch to material preview mode when painting: it uses Eevee and can display materials much better.