How to draw lines only on the face?

Like this, I have drawn a plane, so next I want to continue drawing on this plane, but instead of pointing in Figure 1, I suggest the endpoint - in the group; however I want to suggest on the face like in Figure 2.

I’m not sure I understand your question but this looks like a drone-acquired triangular mesh. They are not very accurate. It’s unlikely that any particular plane or face will have a useful orientation. Instead, you may want to try to get an ‘average’/‘best fit’ plane/face. Try creating a rectangular box and using push-pull and rotate to ‘fit’/align your model box to the mesh model faces. You can do that for the larger building mass and then find the center as a guide to finding the roof lines.

Thanks for your answer, it is indeed a drone model, but my idea is that this kind of hint would be nice if it was just a hint in the plane.

One reason I’m suggesting using shapes is that they are larger and easier to see on the model than lines are. The planes/faces of the mesh are willy-nilly to such an extent that drawing from your own push-pulled shapes is more productive.

Are you using Drone Deploy? Do you have access to point cloud models? In my opinion point clouds are better to work with.

You could try turning off View/Edge Style/Edges, see if you then only get faces for the lines.