Nothing really to do, just move the mouse around and watch the "arm" follow you motion.
This is a pretty rudimentary proof of concept for a larger, real life project I'm working on. The eventual idea is to create a jointed robotic arm that will locate the object nearest to it, then reach out to that object. This project was meant to test the mathematical foundation (basically an application of the Law of Cosines) of the program. Sorry for the blinking, but anything faster than a 0.1 second refresh cycle completely broke the entire thing. A brief disambiguation of each variable name follows: R: This is a measurement of the distance from the "shoulder" of the arm (the black sprite called "Root") to the target (the mouse pointer / pink sprite). L1: The length of the first section of the arm, the green line from the shoulder to the elbow. L2: The length of the second section of the arm, the orange line from the elbow to the target. Both L1 and L2 can be modified for different length arms. Theta2: The angle between the first and second sections of the arm. Theta3: The angle between an imaginary line from the shoulder to the target and the first section of the arm. This variable serves only as a calculation tool and is not used to actually direct the arm. Theta1: The angle between horizontal (-90 degrees in Scratch's terms) and the imaginary line from the shoulder to the target. Again, only a calculation tool. Theta0: The sum of Theta1 and Theta3, or the angle between horizontal and the first section of the arm. This is the angle that the arm actually looks at when working out where to point.
