%For each of the following functions, your team will write the contract, a complete
%description, and examples that work for testing. You will also write
%test functions for every function here. Tests for functions that draw
%are difficult to test directly, so you may carefully describe figure test
%results so that any observer can see if the tests pass.

%Some functions here are trivial, some take 8-10 lines of
%code. Regardless of which functions you are assigned, you must
%understand the workings of every function so that you do well on the
%exam.

%Makes the initial board according to the size parameters. Draws each
%circle from parameter vector once to get handles. For a fixed
%number of cycles, draws and updates every circle structure in the parameter
%vector.
%calls: makeBoard, drawCircles, drawAndUpdateEveryCircle
function [] = project1a(circles,xSize,ySize)

%Creates and returns a board structure
function board = makeBoard(xmin, xmax, ymin, ymax)

%Draws every circle in the vector once, and returns a vector of the
%handles.
%calls: drawCircle
function handles = drawCircles(circleVector)
  
%For each circle, checks to see if circle is touching edge of board. If
%it is, alter the x and/or y velocity accordingly. Then draw the circle,
%keeping the new handle. Be sure to delete the old handle to the previous
%version of this circle. Update the position of the circle according to
%its velocity data. 
%calls: atEdge, reflectCircle, drawCircle, updateCirclePosition, delete (built-in)
function [circleVector handleVector] = drawAndUpdateEveryCircle(circles, handles, board)

%Changes the velocities of a circle that has hit an edge. Determine which
%edge, then modify the circle.
function newCircle = reflectCircle( circle, board )

%Changes the position of a circle to reflect its motion after one cycle,
%based on its velocities.
function newCircle = updateCirclePosition(circle)
 
%Returns true if the edge of a circle is touching an edge of the board;
%false otherwise.
function isAtEdge = atEdge(circle, board)

%Creates and returns a circle structure.  
function circle = makeCircle(xpos, ypos, radius, xVelocity, yVelocity, color)

%Uses the rectangle function to draw a circle on the current figure.
%calls: rectangle (built-in)
function handle = drawCircle(circle)