Processing: Creative Coding and Computational Art

PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART
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isShapeClosed = true;
}
}
The mousePressed() function begins with a conditional block that initializes the sketch
arrays when the shape is closed; this allows new shapes to be plotted when the mouse is
pressed (only after the shape has been closed and has begun animating). I used
Processing’s subset() function to reset the primitive arrays. The function returns a subset
of an array. The first argument is the array to subset, the second argument is the place in
the array to begin the subset, and the third argument is the number of positions in the
array to include in the subset. Since I used 0, 0 for the starting point and number of positions
in the subset, an empty array was returned. Notice that I assigned the empty array
back to the same array I used in the first argument; this may look odd, but it is perfectly
legal. At the end of the conditional block, I reset the variable isShapeClosed to false to
allow new nodes to be plotted.
The next conditional block, if(!isInitialNode()), uses the ! operator with the function
call isInitialNode(). The function call returns a Boolean value (true or false). Prefacing
the function call with the exclamation mark means that the conditional test will evaluate
to true when the function call returns false (i.e., when the user is not pressing on the initial
node). This kind of logic can hurt your head. Instead of using !isInitialNode(), you
could also use isInitialNode() == false or isInitialNode() != true to handle the
test.
Within the conditional block, I used Processing’s append() function. This function
increases the length of arrays. The function takes two arguments: the first argument is the
array to append to, and the second is the value to add to the array. Like subset(),
the append() function returns the changed array, which I reassigned to the same array
variable. On each mouse press, all six of the arrays are appended to. Finally, if the user
clicks the initial node, the arrays are not expanded, but the Boolean variable
isShapeClosed is set to true.
void moveShape(){
//animate after shape is closed
if (isShapeClosed){
for (int i=0; iwidth-nodeRadius){
nodeXPos[i] = width-nodeRadius;
xSpeed[i]*=-1;
}
// left display window edge
if (nodeXPos[i]