For Blender, does anyone know a tool or a way to make line #1 (well technically a collection of 6 linked sides) be line #2? The sides on line #2 would be straight in this case. The gray stuff isn't part of it and the grey vertical lines are just a guideline sort of thing.
So basically take a bunch of line segments and make it look like the side of a half circle.
Okay, follow these intructions.
The line has 7 vertices. From left to right the vertices are numbered 1, 2, 3, and so on. Vertices 1 and 7 define the diameter of the circle and as such are already on the circle, at opposite points. You do not need to change these vertices.
Select vertex 4 which I assume is the exact midpoint between vertices 1 and 7.
Shift+S > Cursor to Selected
Shift+A > Circle (Use as many vertices as you think you'll need. 32 will probably be fine.)
Shift+Ctrl+Tab > Vertex
S > Move your mouse over vertex 1 or 7. You should now have a circle with the diameter of the 7 vertex line.
Select vertices 2, 3, 5, and 6.
Extrude those vertices so the resulting 2 faces overlap the circle.
Zoom in on the spot where one edge of either of the 2 new faces intersect with the circle. Select the two intersecting edges. Pictured below.
W > Edges X Intersection (If you can't see this option you need to enable EdgeTools in Ctrl+Alt+U > Addons)
You now have a new vertex at the exact intersection of these two edges. Repeat for the remaining 3 edges. Don't delete the very top vertex of the circle. It's aligned with vertex 4 so you don't need to do anything to that. Delete all the extra vertices and done:
And here's the circle on top of the final geometry to clear things up a little.
