How to draw eaves when the sky is building?

The simplest and most direct way is that you open the model or build a model, and then you adjust it to the top view and draw what you see. This is how you express the floor plan, expressing the outline, slope and filling. Generally speaking, the sloping roof is sitting on the gutter, but it should also be expressed. What can be seen from the top is represented by solid lines, and what cannot be seen is represented by dotted lines.