Objective: The main point of this project was create a gravitational orbit simulation. Objects would be created in space with a mass, radius, initial velocity, and rotation. These Objects would interact with eachother and enact gravitational force upon and collide with eachother.

Interaction: Users are able to interact in this program both with viewing and manipulation. Users can move the eye position to view the objects from different angles and zoom in and out. In addition, they can interact with the objects by picking an object to modifying it's velocity, and click and dragging objects to change its position.

- Gravitational acceleration

The forces acting upon an object are calculated by iterating across all the objects and calculating the gravity each object will act upon the current object.

a = GMm/r^2

- Collision detection

Object's relative distance to eachother is checked after changing its position based on velocity. If the distance between two objects is less than the sum of its two radii, then it flags the objects as collided.

- Ellastic collisions

Once two objects are flagged as collided, their new velocities are calculated while conserving kinetic energy and momentum of the two objects.

v1 = ( u1(m1-m2) + 2(m2u2) )/( m1+m2 )

v2 = ( u2(m2-m1) + 2(m1u1) )/( m1+m2 )

- Proportional rotational movement and zooming

Movement around the center and zooming in/out is scaled to the view vector

- Texture Mapping

Objects are texture mapped to planet textures

- Time Manipulation

Time can be multipled by 2 from 1x and up

- 3D Picking

Users can select objects in perspective mode and the closest object is picked

- Dynamic skybox and viewspace

The skybox and viewspace is scaled depending on the distance of the eye

To use this you...

Keyboard
d : toggles the display of FPS and each object's velocity vector, mass, velocity and radius
m : toggles the mouse mode look/interact
arrow keys : with an object selected in look mode, modify the object's velocity
+/- : speed up/down
p : pause
q : quit

Modes
look - Users can click and drag with the left mouse button to rotate, and left mouse button to zoom in and out. They can also select objects to view their information and modify its velocity with the arrow keys
interact - Users can click and drag objects with the left mouse button to change its position

planet texture maps - JHT's Planetary Pixel Emporium
elastic collisions - wikipedia: elastic collision
bitmap characters - O'Reilly: OpenGL Rendering and Drawing