When we solve geometry problems we often need to debug them. Using a simple paper and a pencil is boring and it would be much better when you have access to some advanced tools where you have user friendly way to input set of primitives (points, segments).
I know one really cool tool: Dynamic Geometry (DG). It is a little bit outdated and works only for Windows. But there are really cool possibilities to build geometry objects, intersections, perpendiculars, circles, tangents, etc. Then you can move base points and whole picture will move dynamically. It is awesome! Unfortunately it takes some time to add objects from your test.
It would be great to have something similar to DG that allows easily to construct input directly from your C++ or Java code and then you can open it in the tool and see the picture, modify, find intersections, etc.
I am wondering if something similar does already exist and what other tools people use when they want to debug geometry?