Texture paint go weird

Hi all, I’m a beginner to Blender and the community. I got some problem with texture painting function. I hope I place my question in the right forum. Please suggest me if I misunderstanding.

I have modeling and sculpting 2 difference object in this project. There is a turtle shell and turtle body. I can paint texture normally fine with the turtle shell which has lower polygon.

But for the body my computer got frozen and the program has been shutdown afterward. I think it might need too much memory than my computer can proceed. So I tried to lower the polygon resolution by using decimate modifier and it work. Now I can paint on the turtle body.

But after I paint on an object. Painting color painted on an object flew along all the object like a water color and it is uncontrollable. As in the picture, one simple click on an object made a color flow along the object like a weird strip. Not like a normal brush painting.

I tried with another object with quite high polygon resolution. Without decimate modifier function added. But the texture painting got the same problem. I’m using 2.92 Blender version. I also noticed that there is no UV unwrap showing in texture paint UVs tab. Does anyone know how to fix this problem ? I’m so desperate now since I tried to search through both Youtube and blogs but there are nothing close to what I’m looking for. I appreciated to any helps in advance.

Hi

UVs don’t show up in Image Editor unless you select faces of the mesh (easier to do in Edit Mode, but you can do it in Texture Paint as well).

Now UV Editor is what you need to unwrap the mesh so it can be properly textured.
From your words, I’m assuming you didn’t do and kind of retopology after sculpting?
If so, while it’s technically possible to unwrap a decimated sculpt (just slow and probably painful), it’s worth to look into retopology workflow.

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Hi StrayBillie. Thank you for sharing the solution. Now I can see a uv unwrap showing in the uv tabs by following your suggestion. And after I paint in to unwrap uv directly. It’s now look like a normal brush paint in 3D view.

But it’s still impossible for me to paint in that way as an unwrap uv is messed up together. And if I paint to an object in 3D view after it got unwrap already. It still has the water color effect.

I’m very new to Blender and sculpting software. I’m not sure I understand the retopology process correctly. I assume it’s to reducing polygon mesh to make the computer can work with the object and that may make it work with texture painting as well as the software now getting easier to define which mesh is the mesh that need to put a color on. But I still curios why the turtle shell which actually not a low res. polygon can normally paint in 3d view without retopology or uvunwrap process needed.

Here is a picture of the turtle shell in edit mode.

Dear StrayBillie. So now I understand more about your suggest on uv editor. After I unwrap an object with smart uv projection in uv editor. Then now I can paint on it in 3D view without the water color spilling effect. Thank you so much again for taking a look of my problems. I very appreciated!

Glad to hear it!

Retopo is more about optimizing the mesh (which indeed usually leads to polygon reduction).
Sculpting produces very messy topology. From what I see, people normally use Vertex Paint instead of Texture with raw sculpts. Retopology is a process of creating clean mesh, optimized for further sculpting, unwrapping, texturing, posing and animation. It makes things human- (and hardware-) friendly. Done right, you get cleaner forms for less polygons, unwrapping and texturing gets much easier, plus you gain other advantages that come with lower polycount.
It may look intimidating and can often be frustrating (or enjoyable, if you’re lucky to be that type of person). But there are a lot of tutorials and tips out there, and clean mesh is totally worth the trouble, imho.

Good luck and have fun!