Move a rectangle across a window by incrementing a variable. Start the shape at x coordinate 0 and use an if statement to have it stop at coordinate 100. Rewrite the sketch to use constrain( ) instead of the if statement. Fill in the missing code.

// Rectangle starts at location x
float x = 0;

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

void draw() {
  background(255);
  // Display object
  fill(0);
  rect(x,100,20,20);
  // Increment x
  x = x + 1;
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}
Example

exercise_5_3

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

// Exercise 5-3: Move a rectangle across a window by incrementing a variable. Start the shape at x coordinate 0 and use an if statement to have it stop at coordinate 100. Rewrite the sketch to use constrain( ) instead of the if statement. Fill in the missing code.

// Rectangle starts at location x
float x = 0;

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

void draw() {
  background(255);
  
  // Display object
  fill(0);
  rect(x,100,20,20);
  
  // Increment x
  x = x + 1;
  
  // If x is greater than 100
  if (x > 100) {
    // Set it back to 100
    x = 100;
  }
  
  // Using constrain instead
  // x = constrain(x,0,100);
  
}
  • http://twitter.com/stani101 stani

    float x=0;

    void setup(){
     size(250,250);
     smooth();
     //r=random(150);
     //g=random(250);
     //b=random(200);
    }
     
    void draw() {
      background(255);
    stroke(255);
    fill(0);
    rect(x,100,30,30);

    x = x+1;

    if(x<100) {
      x=x+1;
    } else{
      x=0;
    }

    //x = constrain(x,0,150);
    }