topics today:
- random
Colors allows us to talk about the painters algorithm (can't really demonstrate until colors, we need overlapping shapes). The last line of code = "on top". Introduce ofSetColor, ofBackground, ofFill and ofNoFill, opacity, and how grays can be simplified to one number. demonstrate how the state of the colors wraps around to the beginning of the draw loop. best practices: if a function changes the color, at the end change it back to white, full opacity.
for context, show some algorists' work: Molnar, Nees, Mohr, Nake, there was a moment around the use of computational randomness in art.
draw a circle inside draw() with random position or size (see why we have to store the variable?). solve the problem by introducing ofApp.h to store class-wide variables. use setup() to initialize them.
coutto peek inside of variables. "what is inside our random variable?"- discuss start-end range of ofRandom
- show them the seed
quick overview of boolean variables, and how they can be created as a result of a boolean expression. 5 < 10
introduce loops by way of the while loop. our comparison needs to begin as true but eventually becomes false.
what should we do inside this loop that we made? because drawing the same thing over and over has no effect.
challenge: pick a shape (rect, circle, ellipse), pick a property of that shape to become randomized (position, radius, ...), draw many shapes.
Problem: how do you prevent the shapes flashing in random places? ofSetFrameRate(1);. This doesn't solve the problem, we will actually be solving this later in the "arrays" section.
without random, how do we prevent drawing the same shape 100x times on top of itself? we need something that changes within the loop. use the counter iterator.
challenge: maybe a sketch of concentric circles growing in size.
show how while(random(10) < 1) does not do what you probably think it does
now that we know how loops work, we are going to use for loops from now on.
challenge: draw a color gradient by drawing a bunch of vertical lines next to one another the i will be used to change the x-position of the lines, as well as the color.
problem: both position and color are tied to the same variable, how can we make this gradient larger in size than 255, without breaking the colors?
right now the i is too-directly mapped to the location. we can use math (* 2) to increase the size. why is our for-loop between 0 and 255 to begin with?
arrays are a way of storing a list of variables. it solves the problem for how can we store one variable for every iteration of the loop.
watch this video: introduction to arrays
your homework is to play with for-loops, arrays, and random together.
- make a starry-night sky. can you make the stars twinkle?
- can you make a rainy sky? (this is a little more advanced than stars)
alternatively, try playing with loops and arrays without using random to make more regular, geometric kinds of drawings.