# What is the optimal topology for a base with square corner meeting a cylinder?

I would like to make this part:

This is my approach:

In order for the inner edge loops not go all the way to the cylinder, I cut the quad into two triangles. Like this:

But after adding loop cuts, the model still suffers from some pinching.

How can I fix this shading issue? And what is the optimal topology for this shape?

This is my blend file if necessary: Blend File

## 2 Answers

This topology seems to work fine, no visible pinching if you move the vertex a bit:

• Lol this is like magic. I spend a great deal of time pulling vertices around but still got the pinching. Thank you! I'll try this. Sep 13, 2019 at 9:34
• I tried this way and still got pinching. Why does your model look so clean? Did you use my mesh or you created from scratch? Also, how do you deal with the problem that the inner support loop goes all the way to top of the cylinder? I see you join the two triangles. Sep 13, 2019 at 9:45
• I created it from scratch. Not sure about what you mean in your second question. I've edited my answer and linked my file, tell me if it's ok Sep 13, 2019 at 9:48
• Thank you for your kindness. I would like to ask about this: ibb.co/QrBX38Q. How did you create the selected support loop? One of my original problem is that when I try to create the loop, it goes all the way to the cylinder, just like the red lines. That's why I had to cut the two quads into 4 triangles to stop it from continuing, which partly causes the pinching. Sep 13, 2019 at 9:58
• You can create additional edges with the knife tool (K to activate, C to cut perpendicularly, Z to cut through), then to make it parallel to another edge, press GG to slide, then E to make it parallel to the next edge (press F after E to make it parallel to the other edge). Sep 13, 2019 at 10:03

I would use a topology like the following to achieve a smooth transition between the rectangular base and the cylinder.

• Wow, thank you! Very clean, rjg. Sep 13, 2019 at 9:33
• Hi, what about the problem that the inner loop goes all the way to the top of the cylinder? (that's why I cut the quads into two triangles) Is it a good practice to allow the square edges to have only one possible support loop? Sep 13, 2019 at 9:47
• @ĐặngHảiPhụng it's certainly not wrong to only have one loop between the base and the cylinder. It depends on how sharp you want the edge to be. Triangles should be avoided because they can cause the pinch you were experiencing. The difficulty here is, if you want to add another loop you need to adjust the cylinder because otherwise the distribution of the vertices is uneven. You could add your loop cut with CTRL + R and the use the Loop Tools add-on to evenly space each edge loop of the cylinder and correct the rotation afterwards. Sep 13, 2019 at 10:01
• Yup. Another problem is that the loop cut will go all the way to the top of the cylinder, which is why I had to cut the quads into two triangles in my model. I illustrate this issue here, with your model: ibb.co/LZW6hPM. May I ask for your approach to solving this? Sep 13, 2019 at 10:06
• @ĐặngHảiPhụng Yes, as I said you could use the Loop-Tools add-on. For each loop of the cylinder use Space to evenly distribute them in a circle. Repeat that for every edge loop in the cylinder and adjust the rotation of each edge loop along the Z-axis (Space distributes the vertices evenly but the edge loops may have a different Z-rotation to each other). Alternatively you can simply replace the cylinder part with a new cylinder that has the appropriate number of vertices and connect that to the base. The latter is likely faster for this particular case. Sep 13, 2019 at 10:10