Computer Science + Electrical Engineering Project, Angle Projection
Most programming languages (C++, Java) allow you to interface to the computer's serial port (RS-232). If no physical serial port is available then you can use a low-cost UART-to-USB adapter.

Once you are able to send data out over serial you need to build something at the receiving end that interprets this data, probably a microcontroller (AVR, PIC, Arduino). Microcontrollers are very good at interfacing to low-level signals (e.g. analogue or digital 0-5V).

With the microcontorller you can control something like a linear actuator. This will allow you to physically move something. You will need a feedback system to know how far the linear actuator has travelled.

When you are able to successfully read the serial data from your pc program you then need to interpret the number and translate it to a value that corresponds with your linear actuator feedback (e.g. 48 degrees equals to 1.45V measured on an analogue input sent from your actuator feedback.

Based on how you asked your question I think you will have quite a learning curve to scale.

Good luck and feel free to come back here for any related questions you may have.