Processing: Creative Coding and Computational Art

PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART
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called theta, and the radius of the circle. However, the unit circle lives in a polar coordinate
system, not the happy Cartesian system we use on a computer screen. Thus, you also
need to convert from the polar to the Cartesian coordinate system to get your x and y
coordinates. The two general statements to do all of this are as follows:
x coordinate = x position of the center of circle + cos(angle of rotation in radians) * radius
y coordinate = y position of the center of circle + sin(angle of rotation in radians) * radius
Returning to the two trig expressions in the triangle sketch, I used the center of the display
window as the center point of the unit circle, which will also be the center point of the
triangle. The function radians(angle) converts from degrees to radians; the actual conversion
expression is (angle in radians) = (angle in degrees) * pi / 180, which is what the
radians() function encapsulates. Lastly, I used width/2.5 as the radius.
Processing includes a function that lets you control how lines join together. Earlier, you
looked at the function strokeCap(), which controls the end caps of lines. The function
strokeJoin() controls the way the end caps come together to form joints. There are three
different join options, in the form of integer arguments (constants): MITER, which is the
default; BEVEL; and ROUND. This next example uses the triangle code to show the difference
in the respective join options (see Figure 6-39 for the output).
//create 3 triangles
size(600, 200);
background(0);
stroke(255);
noFill();
strokeWeight(10);
smooth();
float x = 0, y = 0;
// sets initial shape rotation
float angle = 30;
// join types
int[]joins = {MITER, BEVEL, ROUND};
for (int j=1; j