Learning Processing: Chapter 4: Example 4-3: Varying Variables

Example

// Learning Processing
// Daniel Shiffman
// http://www.learningprocessing.com

// Example 4-3: Varying variables

// Declare and initialize two integer variables at the top of the code.
int circleX = 0;
int circleY = 100;

void setup() {
  size(200,200);
  smooth();
}

void draw() {
  background(255);
  stroke(0);
  fill(175);
  // Use the variables to specify the location of an ellipse.
  ellipse(circleX,circleY,50,50);
  
  // An assignment operation that increments the value of circleX by 1.
  circleX = circleX + 1;
}

Comments (6)

http://blog.gabrielmathews.com Gabe

so what is the solution to varying the speed at which the circle grows? I wound up using the abs() call as it was in the previous chapter.
admin
In this case, you just want to define a variable for the size of the circle, instead of hardcoding the number 50 in, i.e.
```
int circleW = 100;
int circleH = 100;
```
Then you use those variables when drawing the circle.
```
  ellipse(circleX,circleY,circleW,circleH);
```
And then adjust the values however you like!
```
  circleW = circleW + 1;  // Growing
  circleH = circleH - 1;  // Shrinking
```
http://Blog.gabrielmathews.com Gabe

Thanks. I’m sure I’ll have more questions in the hover chapters…:)
http://twitter.com/stani101 stani

here is my code:

// Declare and initialize two integer variables at the top of the code.float circleSize = 0;float circleX = 100;float circleY = 100;//float speed = 0.0;//float offset = 0.0;void setup() { size(200,200); smooth();}void draw() { background(0); stroke(255); fill(175); // Use the variables to specify the location of an ellipse. ellipse(circleX,circleY,circleSize,circleSize); circleSize++; //speed+=offset; }
http://twitter.com/stani101 stani

to vary speed:

// Declare and initialize two integer variables at the top of the code.int circleSize = 0;int circleX = mouseX;int circleY = mouseY;void setup() { size(200,200); smooth();}void draw() { background(0); stroke(255); fill(175); // Use the variables to specify the location of an ellipse. ellipse(pmouseX,pmouseY,circleSize,circleSize); circleSize++; }
http://twitter.com/stani101 stani

// Declare and initialize two integer variables at the top of the code.
int circleSize = 0;
int circleX = 100;
int circleY = 100;

void setup() {
size(200,200);
background(0);
smooth();
}

void draw() {
//background(0);
}

void mouseMoved() {
//background(0);
ellipseMode(CENTER);
stroke(255);
fill(175);
// Use the variables to specify the location of an ellipse.
ellipse(circleX,circleY,circleSize,circleSize);
circleSize++;
}