Processing: Creative Coding and Computational Art

PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART
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This is not a simple example, so I expect some of you may be scratching your heads a bit
reviewing the code. Notice at the top of the sketch, where I declared global variables, that
I created separate variables for directionX, directionY, and ellipseSpeed. Similarly, as in
the last example, I conceptualized the ellipse’s movement as a vector quantity, keeping
direction and speed as separate quantities. I also declared initial arbitrary values for
directionX and directionY. These two variables represent the direction of the incident
(incoming) vector. This vector must be normalized to be useful in the larger reflection calculation
(R = 2N(N • L) – L). I normalized the vector at the bottom of the setup() function,
with the following lines:
// normalize direction vector
float directionVectLength = sqrt(directionX*directionX + ➥
directionY*directionY);
directionX /= directionVectLength;
directionY /= directionVectLength;
You’ll remember that to normalize a vector, you need to divide each of the vector’s components
by the overall length of the vector, which I did in the previous code snippet. Since
the variables directionX and directionY are randomly assigned values, I couldn’t assume
that they formed a vector with a length of 1 (the length of a normalized vector).
Within the draw() function, I used the following lines to calculate the coordinate values of
the top of the base, which were used in the collision detection:
// calculate length of base top
baseLength = dist(baseX1, baseY1, baseX2, baseY2);
xCoords = new float[ceil(baseLength)];
yCoords = new float[ceil(baseLength)];
// fill base top coordinate array
for (int i=0; i