Why my texture painting is repeating?

Question

I was following the doughnut tutorial made by Blender Guru,and I bumped into some problem:

1.I can't get the purple doughnut in UV editing mode. (So I UV unwrapped,did get a purple doughnut in Texture paint mode(not in UV editing mode),but don't know what would that help or effect anything) (After UV unwrap) (Got a purple doughnut in Texture paint mode)

2.And then I pressed the + New on top of the left panel to add a new image(2048*1042),and used Shading node to add the image to the texture of the doughnut,then I started painting,found out that my texture is repeating. (Add the texture to the doughnut) (The texture repeating)

Sorry for the bad English.

Have a nice day.

Answer 1

It is repeating either because you've unwrapped every quad to the whole UV coordinate space (each quad becomes a square going from x:0,y:0 to x:1, y:1), or because of this setting on your Image Texture node:

What this "Repeat" means is that if a particular point of a mesh is mapped (in the UV map) to a point (texel) outside the texture (e.g. x: -5), then it should be "wrapped" from the other side, so for an image 2048 pixels long, the x: -5 becomes x: 2048-5 = x: 2043. This repeats, so x: -6000 becomes x: 2048-5000 = x: -2952, which becomes x: 2048-2952, which becomes x: 2048-904 = x: 1144. The effect is that a mesh with UV map spanning from x: -6144 to x: 2048 will repeat (horizontally) 4 times.

Go to the UV Editing tab, edit your mesh, select all faces (3, then A) and on the left side see if some of the quads go outside the texture - if so, select everything there (again 3, then A) and scale it down (S) until it fits. If you only see a single quad, then you need to properly unwrap the mesh.

How can I mark the seams to UV unwrap a torus?