OpenGL
The following are screenshots of a chart program with interacted charts, a paint program, and a program that displays the orthographic and perspective projection of a room.
The following are screenshots of the program of the room in the above screenshot, improved to be an art gallery. The application features textured surface, ambient lighting, reflections, transparency, colour tracking, and a built-in screenshot tool, where the screenshot is taken by the application, unlike the default way of taking screenshots. The screenshots shown below are all taken by the aforementioned screenshot tool.