A rudimentary Newtonian gravity simulator. Allows the user to create a system of particles which are attracted to each other using Newton's law of universal gravitation.
click - create a particle.
click + drag - create a particle with initial velocity.
shift + drag - pan the camera.
up arrow - double the current mass.
down arrow - halve the current mass.
left arrow - increase the gravitational constant.
right arrow - decrease the gravitational constant.
f - focus the viewport on the most massive particle. This particle will have
its velocity forced to zero to make the velocities of other particles relative
to it.
v - draw helper lines on all particles showing their velocity.