Rules

Functions shouldn't change global origin

Example

draw_a_square_in_center should only draw a square in center. But it also change the global state of origin. Now poor circle is at right-bottom of scren.

void setup() {
  size(800, 600);
  background(236, 226, 225);
}

void draw() {
  draw_a_rectagle_in_center();
  circle(width/2, height/2, 50);
  
}

void draw_a_square_in_center() {
  translate(width/2, height/2);
  rect(0, 0, 100,100);
}

• Functions don't depend on another

Solution

Use pushMatrix everywhre.

void setup() {
  size(800, 600);
  background(236, 226, 225);
}

void draw() {
  draw_a_rectagle_in_center();
  circle(width/2, height/2, 50);
  
}

void draw_a_square_in_center() {
  pushMatrix();
    translate(width/2, height/2);
    rect(0, 0, 100,100);
  popMatrix();
}

Functions shouldn't depend on another functions state

f(x) = y means y is only depend on x, and global variable in our case :(. A function can operate with global variables, but it shouldn't need caller function's state. Beacuse it's hard for extracting specific part later from that chapter.

Example

Wait what? Why bar didn't centered the circle. When I call from foo it did.

void setup() {
  size(800, 600);
  background(236, 226, 225);
}

void draw() {
  foo();
  bar();
}

void foo() {
  translate(width/2, height/2);
  circle(0, 0, 100);
  bar();
}

void bar(){
  circle(0, 0, 50);
}

Solution

TODO

Style

Function Template

void foo(){
    pushMatrix();

    // Matrix must made sandwich

    popMatrix();
}

Format

Use auto-format from processing's ide. It's bound to C-t (Control-t)

Assign values for visuals in setup()

Info

Processing doesn't follow Cartesian coordinate system.

It uses translate(x,y) to temporarirly changing orign. Each changing lives untill

• Another translate(x,y)
• Popped Matrix