03

Bootcamp 03

new sketch 3.01: "sine"

remind yourself what the sine function looks like. speak in terms of the input and output.

• input: any number on the real number line.
• output: a number between -1 and 1.

breathing screen

a sketch where sine of elapsed time is mapped to colors.

float color = ofMap(sin(ofGetElapsedTimef()), -1, 1, 0, 255);
ofBackground(color);

harmonic motion

a sketch where sine of elapsed time is mapped to position. and play with the frequency of the sine function.

ofBackground(0);
for (int i = 0; i < 20; i++){
    float y = ofMap(sin(ofGetElapsedTimef()*i*0.2), -1, 1, ofGetHeight()/2-100, ofGetHeight()/2+100);
    ofDrawCircle(i * 50, y, 20);
}

new sketch 3.02: "bounce"

create the bouncing screen saver. key take aways:

• store the ball's position in variables x and y.
• introduce the update() method; x and y will be changed in the update.

x = x + 1;
// here, check if it went off screen

if statements

we need if statements to catch the ball from moving off screen. an if statement is like our while loop where the () contains a boolean expression, and only runs if true.

x = x + 1;

if (x > ofGetWidth()) {
	// what here?
}

• the "what here" spot needs to modify the line above it x = x + 1 from a + into a -. how do we modify a line outside of the if statement? make the + 1 into a variable.

part of the leap is to understand how x = x - 1 is equivalent to x = x + (-1), and that the 1 or -1 can be stored in a variable.

copy and paste all the content relating to the x to the y, make sure to change "widths" to "heights".

this introduces our first big problem on code design. many different variables conceptually relate to the same thing. classes help us package related-code bits together.

video content: "particle"

watch this video here and re-code our bounce project into a custom particle class.

expand it by creating an array of particles. (this gets really fun when you add gravity!)

Homework

have fun with sin(ofGetElapsedTimef()), using map for position, colors, try them in a loop, with the i modifying each instance.

expand your bouncing ball into a particle class. can you give each particle a unique direction, speed, color?